Old Micro Written Exams

Question 1

What stage of syphilis is the highest risk for Jarisch-Herxheimer reaction?

Answer 1

Secondary

Question 2

3 clinical manifestations of syphilis that would result in complications if a Jarish-Herxheimer reaction developed?

Answer 2

1) Neurosyphilis
2) Ocular syphilis
3) Cardiovascular syphilis

Question 3

3 treatments for head lice?

Answer 3

1) 1% Permethrin Topical Thearpy
2) Wet combing
3) Oral Ivermectin

Question 4

Burkholderia cepacia

• catalase
• oxidase
• motility
• pyoveridin
• polymyxin

Answer 4

Catalase positive
Oxidase positive
Motility positive
Pyoveridin negative
Polymyxin R

Question 5

3 genomovars of Burkhulderia?

Answer 5

I = cepacia
II = multivorans
III = cenocepacia

Question 6

Burkholderia genomovar with worst post transplant outcome?

Answer 6

III = cenocepacia

Question 7

4 antibiotics to test for sus to B. cepacia?

Answer 7

1) TMP-SMX
2) Meropenem
3) Ceftazidime
4) Ticar-Clav

5) Minocycline
6) Levofloxacin
7) Chloramphenicol

Question 8

Penicillin Resistant corynebacterium?

Answer 8

C. jeikieum

Question 9

Corynebacterium with yellow pigment?

Answer 9

1) C. aurimucosum

2) C. xerosis

Question 10

Corynebacterium with reverse CAMP positive?

Answer 10

1) C. ulcerans

2) C. pseudotuberculosis

Question 11

AST method for Coryne?

Answer 11

Broth microdilution

Question 12

3 other Gram positive Bacilli same AST guidelines as corynebacterium?

Answer 12

1) Arcanobacterium
2) Microbacterium
3) Dermabacter
4) Leifsonia
5) Cellulomonas
6) Turicella
7) Rothia
8) Oerskovia
9) Brevibacterium

Question 13

3 antibiotics to report for coryne?

Answer 13

1) Vancomycin
2) Penicillin
3) Erythromycin

4) Gentamycin

Question 14

3 advantages of MALDITOF?

Answer 14

1) Rapid
2) Decrease cost of consumables
3) Large database

4) Ease of use
5) High throughput

Question 15

1 organism that requires testing in addition to MALDITOF?

Answer 15

Streptococcus pneumonaie
Neisseria gonorrhoea
Neisseria meningitidis

Question 16

4 indications for 16S testing?

Answer 16

1) Typing
2) Unknown ID with other methods
3) Confirm the ID of a rarely isolated pathogen
4) Slow to grow organisms

Question 17

Ecoli 0104- limitations to usual culture method?

Answer 17

It’s a sorbitol fermenter - may not be picked up on SMAC

Question 18

2 ways to test for shiga toxin

- Advantage and disadvantage of each

Answer 18

1) PCR
Advantage: Differentiate sxt1 from sxt2
Disadvantage: Specialized lab equipment and training

2) EIA
Advantage: Minimal training or special equipment
Disadvantage: No culture for typing

Question 19

Source of the shiga toxin gene?

Answer 19

Bacteriophage (sxt phages)

Question 20

3 parasitology fixatives?

Answer 20

1) SAF
2) MIF (merthiolate-iodine formalin)
3) PVA - polyvinyl alcohol

4) Modified PVA - no mercury
5) Schaudinn’s with or without PVA

Question 21

Concentration of formalin usually used in the lab?

Answer 21

10% for helminth eggs and larvae
5% for protozoa and cysts

1:10 stool to formalin

Question 22

Lab monitoring to be done with SAF?
3 times to do it
Benefit in terms of safety

Answer 22

Monitor for formaldehyde vapour (can no exceed 0.75 ppm)

Times: 8 hours and 15 minute exposures
No mercury in it

Question 23

2 parasitology stains

Answer 23

1) Modified trichrome

2) Modified acid fast

Question 24

1 way to culture strongiloides?

Answer 24

In a petri dish on a lawn of Ecoli

Question 25

Best concentration technique for Fasciola?

Answer 25

Sedimentation concentration

Question 26

2 species of bedbugs that infect humans?

Answer 26

1) Cimex lectularis

2) Cimex hemipterus

Question 27

2 methods to elminate bedbugs?

Answer 27

1) Heat room to 50 celcius for 90 minutes

2) Wash in hot water and dryer max setting for 30 min

Question 28

Most common mechanism Staph is non susceptible to vancomycin?
- 2 other antibiotics with this mechanism of resistance?

Answer 28

Thickened peptidoglycan layer

1) Teicoplanin
2) Telavancin
3) Oritavancin

Question 29

2 things to do if Staph MIC to Vancomycin is 8

Answer 29

1) Confirm isolate ID

2) GRD Etest

Question 30

Gold standard for hVISA?

Answer 30

Population analysis profile

Question 31

4 things to address in a Biosecurity Plan?

Answer 31

1) Physical security
2) Personnel suitability and reliability
3) Infectious material and toxin accountability
4) Incident and Emergency response
5) Information security

Question 32

4 vaccines to recommend to lab workers?

Answer 32

1) Neisseria meningititis
2) Hepatitis B
3) Typhoid
4) Influenza
5) Primary polio series

Question 33

4 tests lab workers should have before beginning employment?

Answer 33

1) TB skin test
2) HBV
3) HIV
4) Hepatitis C
5) Varicella serology

Question 34

2 tests to differentiate Kingella kingae from other Kingella species?

Answer 34

1) Produces acid from maltose

2) Beta hemolysis (positive for kingae)

Question 35

1 growth requirement for Neisseria gonorrhoea?

Answer 35

Hemin?

Chocolate agar?

Question 36

2 Neisseria species that are not cocci?

Answer 36

1) N. elongta
2) N. weaveri
3) N. bacilliformis

Question 37

3 Neisseria species that produce acid in glucose and maltose?

Answer 37

1) N. meningititis
2) N. lactamica
3) N. sicca

Question 38

3 mechanisms of pseudomonas carbapenem resistance?

Answer 38

1) Carbapenemase
2) Efflux
3) Porin deletion (OprD)

Question 39

2 antibiotics to test in pseudomonas resistant to carbapenems?

Answer 39

1) Aztreonam

2) Colistin

Question 40

How to fix the prozone effect?

Answer 40

Dilute the sample

Question 41

How to avoid false positives for RF in serology?

Answer 41

Treat the sample with a reducing agent (2-mercaptoethanol or pronase)

Question 42

3 microscopic features of crypto?

Answer 42

1) Narrow budding
2) Capsule
3) Round shape
4) Variation in size

Question 43

1 stain to differentiate crypt from blasto?

Answer 43

Mucicarmine

Question 44

What cryptococcus is in BC?

Answer 44

Cryptococcus neoformans and Cryptococcus gattii

Question 45

2 methods to distinguish C. neoformans from C. gattii?

Answer 45

1) Molecular methods

2) Capsule typing (A, D, AD = neoformans, B, C = gattii)

Question 46

Treatment for cryptococcus

Answer 46

Induction phase = Amphotericin B 0.7-1 mg/kg IV daily x 2 weeks + Flucytosine 25 mg/kg q6h po x 2 weeks
Consolidation phase = Fluconazole 400 mg po daily x 8 weeks
Maintenance phase = Fluconazole 200 mg po daily for >=1 year
*(can stop maintenance phase after a minimum of 1 year if: successful introduction of HAART, CD4 >100, and low or nondetectable VL for >3 months)

Question 47

1 phenotypic test to confirm a KPC?

Answer 47

Modified Hodge Test
or
Disk Inhibition assay with Meropenem with and without Boronic Acid

Question 48

4 organisms that carry KPC?

Answer 48

1) E. Coli
2) K. pneumoniae
3) Pseudomonas
4) Enterobacter cloacae

Acinetobacter, Kleb oxy, Salmonella, Enterobacter aerogenes, Citrobacter

Question 49

Clinical situation for Galactomannan testing?

Answer 49

HSCT patients and neutorpenic patients with hematological malignancies

Question 50

3 false positives for Galactomannan testing?

Answer 50

1) Piptazo
2) Dietary galactomannan
3) Cross reaction with alternaria, paeciliomyces

Question 51

Aspergillus treatment and dose

Answer 51

Voriconazole 6 mg/kg IV q12h x 1 days, then 4 mg/kg IV q12h x 2 weeks then step down to oral 200 mg q12h

Question 52

What do you call bacteria that are inhibited by not killed?

Answer 52

Persisters

Question 53

2 methods for bactericidal testing?

Answer 53

1) Determination of MBC via broth dilution
2) Kinetic Time-kill Assay
3) Serum bacteriocidal in vivo test

Question 54

2 viruses that can not grow in cell culture?

Answer 54

1) HMPV

2) Norovirus

Question 55

Cell line for HSV?

Answer 55

HFL, Vero

Question 56

Cell line for influenza?

Answer 56

RMK

Question 57

2 false positive for malaria rapid Ag test?

Answer 57

1) Cross reaction with RF
2) Previous positive with HRP2 persistence
3) Cross reaction with Leish or Trypano

Question 58

2 false negatives for P. falciparum on malaria rapid Ag test?

Answer 58

1) Low parasitemia
2) Prozone effect
3) P. falciparum strain that does not produce the HRP2 Ag

Question 59

Rabies gold standard for diagnosis?

Answer 59

Tissue biopsy from nape of neck for DFA

Question 60

Rabies finding on pathology?

Answer 60

Negri bodies (eosinophilic intracytoplasmic inclusions) in cells of CNS

Question 61

Most feasible way to diagnose rabies?

Answer 61

PCR of saliva

Question 62

4 times to test neonate for syphilis?

Answer 62

1) Signs or symptoms of congenital syphilis
2) Mother had positive syphilis test in pregnancy and was not treated
3) Mother treated with anything other than Penicillin in pregnancy
4) Mother positive in the last month of pregnancy
5) Mother treated but less than 4 fold decrease in titres

Question 63

5 times to order HCV PCR?

Answer 63

1) Acute infection
2) Immunosuppressed patient
3) Monitor treatment
4) Positive Hep C Ab test
5) Monitoring chronic patient

Question 64

4 reasons for HBV isolated core Ab positive?

Answer 64

1) Window period
2) Previous infection with decreased sAb
3) Chronic infection with low levels of sAg
4) False positive

Question 65

2 mechanisms of CMV resistance?

Answer 65

UL54 polymerase mutation

UL97 mutation - unable to phosphorylation of ganciclovir

Question 66

2 ways to test for CMV resistance?

Answer 66

1) Phenotypic - culture in presence of the drug

2) Genotypic - sequencing

Question 67

How many days to do consecutive QC testing for a new antibiotic?

Answer 67

30

Question 68

How to test proficiency if no external program is available?

Answer 68

1) Interlab samples with another lab
2) Intralab samples with different technologists looking at the same sample
3) Split samples and do with 2 different methods?

Read the CLSI…

Question 69

2 reasons for internal controls in PCR?

Answer 69

1) Check for inhibitors in the sample

2) Ensure the reaction conditions were such that genetic material could be amplified

Question 70

MS patient on Natalizumab.

a. What latent CNS pathogen are they at risk for?
b. What infectious complication can occur when its stopped?

Answer 70

a) JC Virus (also HSV and VZV)

b) PML

Question 71

Elderly woman with encephalitis picture. Lesion in temporal lobe on imaging. CSF reveals 122 WBC (lymphs) and 244 RBC.

a. What is the etiologic agent & syndrome
b. What is best test to confirm diagnosis
c. What is the treatment (dose, duration)

Answer 71

a) HSV, Herpes Encephalitis
b) PCR of the CSF for HSV
c) Acyclovir 10 mg/kg IV q8h x 21 days

Question 72

Pregnant woman with history and findings consistent with Listeria meningitis. Which infection precautions did she not follow? List 5.

Answer 72

1) Should not eat deli meats while pregnant
2) Should not consume unpasteurized cheeses (especially soft ones) while pregnant
3) Should not consume unpasteurized milk while pregnant
4) Should wash fruits and vegetables thoroughly prior to consumption
5) Thoroughly cook raw meat to safe internal temperature
6) Keep fridge less than 4.4 degrees celcius and freezer less than -17.8
7) Wash hands, knives, cutting boards after handling raw food
8) Do not eat refrigerated pates and meat spreads
9) Do not eat refrigerated smoked seafoods unless it’s been cooked

Question 73

Duration of antibiotics for different bacterial meningitis:

Neisseria meningititis 
Haemophilus influenza 
Streptococcus pneumoniae 
GBS 
Aerobic GNB 
Listeria

Answer 73

Neisseria meningititis = 7 days
Haemophilus influenza = 7 days
Streptococcus pneumoniae = 10-14 days
GBS = 14-21 days
Aerobic GNB = 21 days
Listeria = 21 days

Question 74

What are the animal reservoirs postulated for H7N9 and MERS-CoV?

Answer 74

H7N9 = Avian species, especially poultry 
MERS-CoV = Bats or Camels

Question 75

What are the incubation periods to monitor contacts of H7N9 and MERS-CoV for?

Answer 75

H7N9 = 10 days 
MERS-CoV = 14 days

Question 76

List 8 countries where MERS CoV has been confirmed.

Answer 76

1) Lebanon
2) Saudi Arabia
3) Oman
4) Jordan
5) Kuwait
6) Qatar
7) Yeman
8) United Arab Emerits
9) France
10) Italy
11) Egypt
12) Iran
13) Algeria

Question 77

HIV+ patient diagnosed with Crypto meningitis. What are the phases of management & specific doses and durations for each phase?

Answer 77

Induction phase = Amphotericin B 0.7-1 mg/kg IV daily x 2 weeks + Flucytosine 25 mg/kg q6h po x 2 weeks
Consolidation phase = Fluconazole 400 mg po daily x 8 weeks
Maintenance phase = Fluconazole 200 mg po daily for >=1 year
*(can stop maintenance phase after a minimum of 1 year if: successful introduction of HAART, CD4 >100, and low or nondetectable VL for >3 months)

Question 78

List all the major and minor criteria for Modified Duke’s Criteria

Answer 78

Major:

1) Blood culture positive for IE
- VGS, NVS, Strep gallolyticus, HACEK, S. aureus, Enterococcus without focus from 2 separate sets
- Organisms consistent with IE from persistently positive blood culture (>=2 bottles >12 hr apart, all of 3 bottles or majority of >=4 from >1 hr from first to last)
- Single positive culture for Coxiella burnettii or anti Phase I IgG >1:800

2) Evidence of Endocardial Involvement (Echo positive for IE)
a) New or partial dehiscence of a PV
b) Abscess in the tissues surrounding a heart valve
c) New regurgiant murmur
d) intracardiac mass

Minor:

1) Fever (>38)
2) Predisposition (PV, Turbulent or reguritent flow, IVDU)
3) Vascular phenomenon (emboli, ICH, subconjuntival hemorrhages, Janeway lesions)
4) Immunologic phenomenon (GN, Roth’s spots, Osler’s nodes, RF)
5) Positive blood cultures that do not meet defintions of major criteria or serological evidence of active infection with organism consistent with IE

Definitive IE = Pathological/Culture positive OR
2 major OR
1 major and 3 minor OR
5 minor

Possible IE = 1 major and 1 minor OR
3 minor

Question 79

What are 3 risk factors for invasive aspergillosis?

Answer 79

1) Allogenic Hematopoetic Stem Cell transplant recipient
2) Hematological malignancy with neutropenia
3) Lung Transplant patients
4) Heart Transplant patients
5) GVHD
6) CGD
7) HIV

Question 80

What is the treatment of choice for CNS aspergillosis?

Answer 80

Voriconazole 6 mg/kg IV q12h x 1 day, then 4 mg/kg q12 h

Question 81

Clinical history of an allo BMT patient, who had suffered from cGVHD and been on steroids, who became acutely unwell with respiratory failure, infiltrates on CXR and hypoxemia. Patient had BAL performed, which was negative for usual bacterial, and fungal pathogens. Resp virus multiplex negative.

a) What are 2 possible non-viral etiologies of these symptoms?
b) You suspect CMV. What 2 tests would you to confirm & what empiric treatment would you give?

Answer 81

a) PCP (shouldn’t be that acute)
Nocardia
Legionella
NTM (Mycobacterium avium, Mycobacterium kansasii)
TB
Mycoplasma pneumonia

b)
Tests = PCR for CMV, pp65 antigen assay, shell vial assay with DFA
Treatment = Gancyclovir + CMV immune globulin

Question 82

Name 2 pathogens associated with handling fish.

Answer 82

1) Erysipilothrix rhusopathiae

2) Streptococcus iniae

Question 83

Name 3 pathogens associated with SSTIs after water exposure.

Answer 83

1) Aeromonas hydrophila
2) Vibrio vulnificus
3) Mycobacterium marinum
4) Edwardsiella tarda
5) Erysipilothrix rhusopathiae

Question 84

32M in Amazon on canoeing trip. Got appropriate malaria prophylaxis. Upon return home, developed 20% eosinophilia and cough and pulmonary infiltrates. Name this syndrome & 4 parasites (to genus) which could cause it.

Answer 84

Syndrome = Loeffler’s syndrome
Parasites:
1)	Nectator
2)	Ancyclostoma
3)	Ascaris
4)	Strongyloides
5)	Toxocara

Question 85

A patient with IBD is going to be started on a biologic. Give 4 suggestions for workup of this patient.

Answer 85

1) TB Skin Test
2) Hepatitis B serology
3) Hepatitis C serology
4) HIV serology

Question 86

A patient is confirmed to have active pulmonary TB.

a. As infection control officer, what 4 things do you need to do?
b. You are asked to review system for occupational health exposures on the medical ward affected. What metrics would you use to do this?

Answer 86

a)
1) Place the patient on airborne precautions
2) Ensure the staff are fit testing for N95 respirators
3) Notify public health
4) Ensure the patient will have DOT with medication
5) Contact tracing
6) Identify the index case

b)
TB Skin testing results prior to exposure
Follow up TB skin testing
Assess any TB skin test conversions

Question 87

Name 3 pathogens that require airborne precautions.

Answer 87

1) Mycobacterium tuberculosis
2) Measles virus
3) Varicella virus
4) SARS
5) Smallpox

Question 88

Confirmed measles case in kid.

a. What type of precautions & for how long?
b. What PEP can be given and in what time frame (2 boxes to fill in)
c. What do you do for the mother?

Answer 88

a) Airborne until day 5 of the rash
b) Measles gamma globulin within 6 days of the exposure
Can also give measles vaccine within 72 hours of the exposure
c) Ask if she has previous had measles, the measles vaccine or if she was born before 1970. Also check if she is pregnant or not.

Question 89

Mechanism of action of daptomycin

Answer 89

Calcium dependant depolarization of the cell membrane by binding to the cell membrane, causing inhibition of DNA, RNA and protein synthesis

Question 90

1 contraindication to daptomycin use

Answer 90

Contraindication = Pneumonia

Question 91

3 organisms not covered by erta that are covered by other carbapenems.

Answer 91

1) Pseudomonas aeruginosa
2) Acinetobacter species (baumannii or calcoaceticus complex)
3) Enterococcus species (especially faecalis)

Question 92

Best carbapenem for amp-susceptible E. faecalis? Best for E. faecium (not details given)

Answer 92

E. faecalis = Imipenem

E. faecium = Imipenem? Or none?

Question 93

When is meropenem preferred over imipenem?

Answer 93

When covering for Morganella morganii, Proteus mirabilis, Proteus penneri, Proteus vulgaris, Providencia rettgeri as they can have higher MICs to Imipenem.
Burkholderia cepacia is intrinsically resistant to imipenem but meropenem can have activity.
Also when there is a risk for seizures.

Question 94

Name 3 infection control requirements for patient on airborne precautions.

Answer 94

1) Negative pressure airflow
2) Single room
3) Air exhausted outdoor or HEPA filtered if recirculated
4) 6-12 air exhanges per hour
5) Patient to remain in room or wear mask when leaving

Question 95

24. Norovirus outbreak in LTCF with 40 beds. You are Infection control officer and are called in to manage outbreak. You plot the epi curve. They gave a propagated epi curve with index case, followed by 2 peaks.
    a. Name 6 control measures you would implement.

Answer 95

1) Patient isolation
2) Strict hand hygiene
3) Restrict visitors
4) Close the unit to new patients
5) Increase cleaning and disinfection of the unit
6) Exclude ill employees until 48 hours after symptoms resolved
7) Dedicate equipment to patients
8) No meetings or gatherings in outbreak zone

Question 96

What are the 5 types of outbreaks based on an epidemiological curve?

Answer 96

A. Common Source Outbreaks

a. Point Source Outbreak with no Propigation (Summer BBQ)
b. Continuing Source Outbreak (Contaminated Water Supply)
c. Intermittent Outbreaks (Seasonal)

B. Person to Person Spread

a. Index Case with Limited Spread (Returning traveller infects others)
b. Propigated Spread – Disseminated Outbreak originating from an index case with propagated spread

Question 97

What are 2 features of norovirus that would make it hard to control, despite appropriate standard precautions?

Answer 97

Extended shedding of the virus in stools
Can survive for days on surfaces
Nonenveloped virus that can resist disinfection
Low infectious dose
Multiple modes of transmission
Short incubation period

Question 98

List 5 indications for quadrivalent meningococcal vaccination.

Answer 98

1) Travel to an endemic area
2) Microbiology Laboratory workers
3) Outbreaks
4) Close contacts of a positive case of Neisseria meningitis
5) Military personnel
6) Healthy persons aged 12-24 years
7) Functional or anatomical asplenia
8) Congenital immunodeficiency
9) Patients treated with eculizumab

Question 99

List 6 indications for PCV-13 in adults.

Answer 99

1) Functional or anatomical asplenia
2) Bone marrow transplant recipients
3) Solid organ transplant recipient
4) HIV positive
5) Immunosuppression therapy
6) Sickle cell or other hemoglobinopathies
7) Congenital immunodeficiencies
8) Malignant neoplasms including lymphoma and leukemia

Question 100

List 6 groups in which treatment with antivirals would be recommended for influenza.

Answer 100

1) Anyone with influenza presenting in the first 48 hours after symptom onset
2) Over 65 years
3) Children aged 1-5
4) Underlying asthma
5) Diabetics
6) COPD
7) Pregnant women and up to 4 weeks post partum
8) <18 on Chronic Aspirin
9) Obesity
10) Nursing Home
11) Malignancy

Question 101

List 3 contraindications to the rotavirus vaccine

Answer 101

1) Allergy to any components of the vaccine
2) Previous intussceception
3) Immunocompromised
4) Uncorrected congenital abnormality of the GI tract that would predispose to intusseception

Question 102

32M bit by dog in Nepal. Returns to Canada 10 days later. Wound is healing and looks ok.
a. What 4 interventions would you do in him to prevent rabies?

Answer 102

Instill wound with rabies immunoglobulin
Give rabies vaccine
Wash wound with soap and water (but it’s 10 days old..)
If the wound has been stitched remove the stitches?
Contact

Question 103

What is the best specimen for diagnosing rabies and would tests should be done on it?

Answer 103

Tissue biopsy from the nape of the neck for DFA or PCR

Can also do PCR from the CSF or saliva

Question 104

What are the two forms of clinical rabies?

Answer 104

Furious – hydrophobia, delirium, agitation, aerophobia

Paralytic – Ascending paralysis

Question 105

What are 6 risk factors for CA-MRSA 10/USA300

Answer 105

1) Incarceration
2) Contact with positive individual
3) Owning a dog
4) Skin trauma
5) Cosmetic body shaving
6) IVDU
7) Native and Aboriginal communities
8) MSM
9) Group homes

Question 106

Name an integrase inhibitor that can cause increased CK.

Answer 106

Raltegravir

Question 107

Name an integrase inhibitor that can be used in integrase inhibitor experienced patients.

Answer 107

Dolutegravir

Question 108

Name 4 Health Canada approved antivirals that can be used with PR (PEG interferon with Ribavirin) for treatment of HCV.

Answer 108

Sofosbuvir
Semepravir
Teleprivir
Bocepravir

Question 109

What are 6 risk factors, except for co-infections, that are associated with increased risk for developing cirrhosis in HBV.

Answer 109

1) Alcohol
2) High Hepatitis B viral load (>2000)
3) eAg positivity
4) sAg >1000 IU/mL (in eAg negatives)
5) Male
6) Prolonged replication phase
7) Hepatitis D superinfection
8) Age >50

Question 110

MRSA endocarditis

a. Treatment (agents, duration) for native valve & prosthetic valve IE

Answer 110

Native valve = Vancomycin x 6 weeks

Prosthetic valve = Vancomycin x 6 weeks + Rifampin x 6 weeks + Gentamycin x 2 weeks

Question 111

What 2 measures besides treatment would you take in a case of MRSA IE?

Answer 111

Surgical intervention
Patient decolonization
Repeat blood cultures in 2-4 days
Look for source of seeding infection

Question 112

Question about debridement & retention strategy for treating prosthetic joint infection.
a. What 4 factors must be considered in this decision?

Answer 112

1) Time since initial surgery (<30 days)
2) Organism
3) Presence of a sinus tract
4) Joint loosening

Question 113

What is the treatment of choice for a Proprionibacterium infection?

Answer 113

Penicillin

Question 114

Parvovirus

a. 4 clinical syndrome associated with besides erythema infectiosum

Answer 114

1. Pure red cell aplasia
2. Transient aplastic crisis
3. Fetal hydrops
4. Arthropathy
5. Papular purpuric gloves and socks syndrome

Question 115

A women is exposed to her child who has Parvovirus when she’s 18 weeks pregnant.

a) What 2 tests can be offered to her?
b) What treatment can be offered to her

Answer 115

a)
Parvovirus serology
Parvovirus PCR

b) Intrauterine transfusion

Question 116

2 mechanisms of resistance of candida specie to azoles.

Answer 116

1. Mutation in 14-a-demethylase

2. Efflux pump

Question 117

1 resistance mutations associated with echinocandin resistance.

Answer 117

Mutation in the B 1,3 glucan synthase

Question 118

1 antifungal that can develop rapid resistance to on monotherapy

Answer 118

Flucytosine

Question 119

One species of aspergillus that is usually amphoB resistant.

Answer 119

Aspergillus terres

Question 120

Hepatitis E. 4 extra-hepatic manifestations and complications.

Answer 120

1. Pancreatitis
2. Kidney Injury
3. Hematological Disorder – thrombocytopenia, aplastic anemia
4. Neurological Disorder – GBS, Bell’s palsy, Neuralgic amyotrphy, Acute transverse myelitis, Acute meningoencephalitis
5. Arthralgias
6. Urticarial rashes

Question 121

44. Described clinical scenario of some dude helping out there post-tsunami and coming back and becoming really sick with lung infiltrates. Cultures grew GNB with was growing as LF, safety pin appearance on gram stain.
    a. What is the pathogen?
    b. What is the treatment?

Answer 121

a) Burkholderia pseudomallei
b)
Meropenem + TMP-SMX x 14 days or
Ceftazidime + TMP-SMX x 14 days
The initial regime then needs to be followed with TMP-SMX for at least 3 months for the eradication phase

Question 122

Women who went on vacation to Martha’s vineyard, then showed up with conjunctivitis and pre-auricular LAN on the same side.
a. What are 4 bacterial pathogens that could cause this syndrome?

Answer 122

1. Bartonella henselae
2. Fransicella tularensis
3. Chlamydia trachomatis
4. Listeria monocytogenes
5. Mycbacterium tuberculosis
6. Treponema pallidum

Perinodes Ocular Glandular Syndrome

Question 123

Guy goes to Nantucket to do some outdoors activities. Returns with fever etc and is confirmed to have anaplasmosis.
a. What is the confirmatory finding on peripheral smear?

Answer 123

Morulae (intracytoplasmic inclusions) in neutrophils

Question 124

What is the treatment for Anaplasma, dose, duration?

Answer 124

Doxycycline 100 mg po bid x 10 days

Question 125

12yo Kid goes hiking for a week, and returned 2 days ago. Parents have found tick (no details re: what kind) and are curious about lyme prophylaxis. You see tick attached to his thigh.
a. What are 4 considerations in making decision to prophylax?

Answer 125

1) Attached tick identified as Ixoides scapularis adult or nymph
2) Tick estimated to be attached for >=36 hours (degree of engorgement)
3) Prophylaxis can begin within 72 hours of removing tick
4) Local rate of infection of ticks with B. burgdorferi is >=20%
5) Doxycycline is not contraindicated

Question 126

What is the drug, dose, duration for Lyme Disease prophylaxis?

Answer 126

Doxycycline 200 mg po x 1

Question 127

Name 4 gram positive pathogens that cause gastroenteritis.

Answer 127

1. Listeria monocytogenes
2. Bacillus cereus
3. Staphylococcus aureus
4. Clostridium perfringes

Question 128

Guy is in Thailand and gets febrile illness. Acute and convalescent Dengue serology performed. Acute: IgM-, IgG+; Convalescent: IgM+, IgG+
a. Explain the serologic findings

Answer 128

He may have already been IgG positive from another flavivirus or previous Dengue. Likely has acute Dengue

Question 129

According the new 2009 WHO classification of severe Dengue, describe 3 findings that are associated with it.

Answer 129

1. Severe Plasma Leakage
   a. Shock
   b. Fluid accumulation with respiratory distress
2. Severe bleeding
3. Severe Organ Involvement
   a. Liver: ALT or AST >1000
   b. CNS: Impaired consciousness
   c. Failure of heart and other organs

Question 130

Should the following people receive the Zoster vaccine?

a. 60M actively on chemo for lymphoma
b. 24F RN, with history of chicken pox in past, who was exposed to patient with disseminated zoster.
c. 65M with no history of chicken pox in the past.
d. 62F with history of shingles in V1 dermatome.

Answer 130

a) No
b) No
c) Yes
d) Yes

Question 131

Clinical vignette re Chagas disease.

a. What are 2 complications of chronic Chagas disease (from different organ systems)

Answer 131

1. Myocarditis
2. Megaesophagus
3. Megacolon

Question 132

Besides serology, what are 2 ways to confirm a diagnosis of Chagas, and in which phase of the disease would you use each one.

Answer 132

Peripheral blood smear to see the trypomastigoes in the acute stage
Biopsy to see the amastigotes in the later phase

Question 133

What are 4 ways Chagas can be transmitted?

Answer 133

1. Bite of a reduvid bug
2. Blood transfusion
3. Organ transplant
4. Vertical transmission from mother to fetus

Question 134

52. Fidaxamicin

a. What type of antibiotic is it?

Answer 134

Macrocyclic

Question 135

What are 3 advantages of using Fidaxomycin over Vancomycin?

Answer 135

1) Bactericidal
2) Narrower spectrum
3) Decreased recurrence of C. difficile for non-NAP1 strains
4) Less renal toxicity

Question 136

4 causes of non-gonoccocal urethritis in men.

Answer 136

1. Chlamydia trachomatis
2. Mycoplasma genitalium
3. Trichomonas vaginalis
4. Herpes Simplex Virus
5. Ureaplasma urelyticum
6. Candida albicans
7. Adenovirus

Question 137

2 genetic tests that can help predict response to treatments for viral infections.

Answer 137

1. CCR5 tropism assay for Maraviroc treatment in HIV

2. Il28B polymorphism for Interferon and Hepatitis C

Question 138

You get a call from a physician regarding a result on a pediatric patient with mild URTI symptoms. Kid has NP sample positive for FluA, FluB, Adenovirus.
a. What is the best explanation for this?

Answer 138

Recently had the intranasal live flu vaccine and has an URTI with Adenovirus

Question 139

What are 2 disadvantages of using PCR testing for respiratory viruses, instead of culture?

Answer 139

1. Unknown if it represents colonization vs infection (the PCR may be too sensitive)
2. Only detects virus which the PCR has primers too, cell culture can grow many types of viruses
3. Can not type viruses for surveillance

Question 140

Chronic lymer story given as vignette.

a. Briefly describe the diagnostic algorithm used for Lyme.

Answer 140

Screening ELISA for IgG and IgM antibody to lyme (C6 peptite ELISA)
Nonreactive reported as negative
Reactive or Intermediate then have a western blot done
If there are >=5/10 positive IgG bands or >=2/3 positive IgM bands it is reported as Reactive for IgG or IgM respectively
If there are less bands than that the sample is reported as NonReactive

Question 141

What are 2 other Borrellia species that cause Lyme and what impact do they have on serologic results?

Answer 141

European lyme:
1) Borrelia garinii
2) Borrelia afzeli
These would give a positive ELISA Ab screen but may be negative on Western blot. Need to request European Lyme serology if questioning these pathogens.

Question 142

EBV serology:

EBV VCA IgM+
EBV VCA IgG+
EA IgG-
EBNA-
Interpret

Answer 142

Acute EBV infection

Question 143

Doctor calls you asking about PCR for a suspected CJD case.

a. What do you say? (4 lines given for answer)

Answer 143

There is no PCR test however can test the CSF for different proteins (14-3-3, tau, SP100). Also with brain material can use immunohistochemistiry stain to detect the abnormally folded prion proteins. If you have frozen tissue can to an analysis for protease resistant forms.
There is an investigational assay called protein misfolding cyclic amplification (PMCA)

Question 144

What is the gold standard for diagnosis of CJD

Answer 144

Examination of brain material for:

1) neuronal loss
2) reactive gliosis
3) vacuolation of the neuropil (spongiform change)

Question 145

Doctor orders serum for Meningococcal IgM

a. As the laboratory Dr, what do you do immediately?

Answer 145

Call the ordering physician and ask them to collect blood and CSF samples for culture and/or PCR instead if N. meningititis is suspected
Also treat empirically and call infection control

Question 146

A laboratory technologist handled the serum sample for meningococcal IgM and is worried. What do you say?

Answer 146

Provided she followed routine micro precautions she is safe
The greatest risk is in disturbing colonies of growth
Furthermore the technologists risks in working with Neisseria meningitis may be reduced if they previously had the vaccine

Question 147

Patient grows GNB that on TSI is glucose positive, lactose negative, sucrose not given, small amount H2S. Citrate negative. Indole negative. Poly O positive. Group D positive. Vi positive.

a. What is the most likely ID?

Answer 147

Salmonella Typhi

Question 148

What other 2 Salmonella species are Vi positive?

Answer 148

Salmonella Paratyphi C

Salmonella Dublin

Question 149

3 reasons why the O can be negative for Salmonella species

Answer 149

1) Vi is blocking it (boil the sample)
2) It is a rough strain and does not make complete O antigens
3) Mucoid and won’t agglutinate the O antisera

Question 150

Salmonella Typhi and Paratyphi A reactions for:
Citrate
Lysine
H2S
O Group
Vi Antigen

Answer 150

Salmonella Typhi = Citrate Neg, Lysine Pos, Small H2S, O Group D, Vi Positive

Salmonella Paratyphi A = Citrate Neg, Lysine Neg, H2S Neg, O Group A, Vi Negative

Question 151

What are the 8 steps in the HIV lifecycle and which ARV works at each step.

Answer 151

1. Binding/Attachment to cell receptor – Entry inhibitors
2. Fusion/Uncoating – Fusion Inhibitors
3. Reverse Transcription – NNRTI, NRTI
4. Integration into the host genome – Integrase inhibitors
5. Transcription and Translation
6. Processing – Protease Inhibitors
7. Assembly
8. Budding/Release

Question 152

Which 2 HIV variants are relatively resistant to NNRTIs?

Answer 152

HIV2

HIV1 Group O

Question 153

An isolate grows from a blood culture and is confirmed as Abiotrophia.
a. What are two ways to allow this organism to grow on BAP?

Answer 153

1) Grow it around a streak of Staphylococcus aureus
2) Add pyridoxal to the agar
3) Use a pryidoxal disk on blood agar for satelitting test

Question 154

b. A physician calls you regarding using penicillin to treat a patient with Abiotrophia bacteremia. What do you say?

Answer 154

The organism is may have higher MICs to penicillin
Susceptibility testing can be done and there are CLSI criteria
Suggest susceptibility testing and while awaiting results if concerned about endocarditis would add Gentamicin to the treatment.

Question 155

According to the Canadian Biosafety Standards and Guidelines (CBSG), please give examples of the types of characteristics that should find for surface finishings and flooring

Answer 155

Made from non-absorbent material
Able to withstand disinfectants
Resistant to scratches

Smooth surfaces without cracks and grooves
Flooring should be slip resistant

Question 156

According to CBSG, what the 3 requirements for a basic laboratory that does very simple and low volume work?

Answer 156

Bench top surfaces
BSLII cabinet
Designated area
Lockable doors

Question 157

Give 3 advantages and 3 disadvantages to consolidation.

Answer 157

Advantages:  
Improved technology
Standardized procedures
May be able to offer extended laboratory hours
Cost reductions

Disadvantages:
Transportation logistics for specimens
Doctors do not have an on site laboratory to consult
May delay reporting of certain tests
Physical space required

Question 158

Give 4 advantages and 2 disadvantages to IGRA testing compared to TST.

Answer 158

Advantages:
- No cross reaction with BCG vaccine
- Patient does not have to return for a second reading
- Less subjectivity in interpreting the test
- Positive result does not cause skin discomfort to the patient
Disadvantages:
- Costly
- Requires specimen to be processed quickly
- Special equipment and technical expertise required

Question 159

What bacteria is used as a biologic indicator usually and what is the purpose of this?

Answer 159

Geobacillus stearothermophilus – resistant to heat

Question 160

What other 3 methods are used to ensure sterility is met.

Answer 160

1. Chemical indicator (Autoclave tape)
2. Mechanical indicator (Print out from the machine which indicates that the correct temperature and pressure were met)
3. Biological Indicator

Question 161

What are 4 immunizations that should be given to laboratory workers before they start their jobs?

Answer 161

1. Quadravalent meningococcal vaccine
2. Hepatatis B vaccine
3. Annual influenza vaccine
4. Typhoid vaccine
5. Polio
6. Hepatitis A vaccine
7. Rabies vaccine
8. Japenese Encephalitis vaccine
9. Yellow Fever Vaccine
10. Smallpox

Question 162

What is the purpose of concentrating stool O&P specimens? What are the 2 methods available to do this?

Answer 162

Increase sensitivity

Sedimentation concentration
Floatation concentration (Zinc Sulfate)

Question 163

An HIV+ patient presents with 3 weeks of diarrhea. Iron haematoxylin negative. What 2 other stains would you do and what organisms would you be looking for?

Answer 163

Modified Acid fast stain for Cyrptosporidium

Modifed Trichrome stain for Microsporidium

Question 164

47M spends a lot of time in Thailand and presents with weight loss, LAN, unwell, etc. Biopsy of bone yields a yeast that is found intracellularly to be (3x3 um) and extracellularly to be up to 5x5 um. Some internal septations are noticed in the yeast.
What is it?

Answer 164

Penicillium marneffii

Question 165

What is the acceptable % contamination rate for blood cultures? What are 2 other pre-analytical QIs for blood cultures?

Answer 165

<3%

Pre analytical QI =
Volume of blood per bottle
Number of bottles collected
Specimen Labelling

Question 166

What are 5 post-analytical QIs?

Answer 166

1. Turn around time for gram stain
2. Gram correlation to final ID
3. Satisfaction of physican with reporting modality
4. Time until the patient is put on organism specific antibiotics
5. Time until final report is issued to the physician
6. Accuracy of the report issued
7. Number of corrected and amended reports

Question 167

What are 4 phenotypic characteristics of Enterobacteriaceae?

Answer 167

1. Glucose fermenters
2. Gram negative bacilli
3. Facultative anaerobes
4. Non spore forming

Question 168

What are 2 phenotypic characteristics of Pseudomonadaceae?

Answer 168

Gram negative bacilli
Catalase positive
Motile

Question 169

What are 2 functions of MALDI TOF?

Answer 169

Rapid identification of organisms
Strain typing
Antimicrobial resistance

Question 170

What are 2 reasons for performing extraction on isolates for MALDI TOF.

Answer 170

To increase chance of ID of an organism
Inactivate organism
Improve sample stability

Question 171

Name 5 hemorrhagic fever viruses.

Answer 171

Ebola
Marburg
Crimean-Congo
Machupo
Dengue virus 
Lassa Fever
Rift Valley Fever
Hantaan

Question 172

What is the vector for and disease caused by:

a. R. prowazeckii
b. B. bacilliformis
c. Leishmania
d. Loa loa
e. Coltivirus – Yes = Colorado Tick Fever Virus, wood tick (Dermacentor andersoni)
f. Lyme - Yes
g. Crimean Congo Hemorrhagic Fever - Yes
h. Babesia microti – Yes

Answer 172

a) Louse, Epidemic typhus
b) Sandfly, Oroya fever and Verruga Peruana
c) Sandfly, Leishmaniasis
d) Chyrsops fly

Question 173

What is the vector and disease caused by:

e) Coltivirus
f. Lyme
g. Crimean Congo Hemorrhagic Fever
h. Babesia microti

Answer 173

e) Tick, Colorado Tick Fever Virus
f) Tick
g) Tick
h) Tick

Question 174

Person in the ICU has suspected pulmonary invasive aspergillosis. Galactomannin is requested.
a. What is the best type of sample to be tested for galactomannin in this setting?

Answer 174

BAL

Question 175

What are 4 causes of false positive galactomannin?

Answer 175

1. Piptazo or Amox-Clav
2. Dietary Galactomannan
3. Paeciliomyces
4. Alterneria
5. GI gut bacteria (Bifidobacterium)

Question 176

What is another serum test that is approved for testing for invasive fungal infection?

Answer 176

Test for B-1,3 D glucan

Question 177

Bronch specimen that grew white fluffy mould after 14 days in culture on BHI agar.

a. What are 3 possible identities of this mould?

Answer 177

Histoplasma capsulatum
Blastomyces dermatitidis
Coccidiodes imitans

Question 178

What 3 things should be done with a 14 day white, fluffy mould from a safety perspective?

Answer 178

Tape the plates
Specimen should be in a BSC Level II Cabinet
Refer to reference lab equipped to process these specimens

Question 179

What are 4 phenotypic differences between T. rubrum and T. mentagrophytes

Answer 179

1) Pigment: Rubrum=red, Mentagrophytes=not red
2) Spiral hyphae: T. mentagrophytes=yes, T. rubrum=no
3) Microconidida: T. mentagrophytes=globose, T. rubrum=teardrop (birds on a wire)
4) Urease: T. mentagrophytes=positive, T. rubrum=negative
5) Hair perforation test: T. mentagrophytes=positive, T. rubrum=negative
6) Macroconidia: T. mentagrophytes=cigar shaped, T. rubrum=pencil shaped

Question 180

Question re: NAP1 strains.

a. Why does this strain produce more toxins?

Answer 180

tcdC which usually inhibits toxin production is mutated (partial deletion) which allows for hyperproduction of toxins

Question 181

What antibiotic is this NAP-1 C. diff more resistant to than other C. difficile strains?

Answer 181

Cipro

Question 182

What are 2 rapid assays your laboratory could introduce to quickly test for C. difficile?

Answer 182

Toxin Immunochromographic assay

PCR

Question 183

What are 3 advantages and disadvantages of the Gene Xpert TB system?

Answer 183

Advantages
-	Able to detect TB from direct samples
-	Able to assess for rifampin resistance directly from the sample
-	Does not require live cultures (safety)
-	Little training required
Disadvantages
-	Expensive
-	Limited throughput
-	Only detect M. tuberculosis
-	Decreased sensitivity in smear negative
-	Detects dead and alive organisms
-	Has to be maintained at 30 degrees

Question 184

What are 4 phenotypic and 2 genotypic test to differentiate slow growing mycobacteria in culture?

Answer 184

Phenotypic 
o	Pigment
o	Niacin Accumulation
o	Nitrate reduction
o	Colonly morphology
o	Temperature
o	Growth Rate 

Genotypic

• Line Probe Assay
• 16s rRNA Gene Sequencing
• hsp65
• Accuprobe Assay

Question 185

What are 4 bacteria that are intrinsically resistant to vancomycin?

Answer 185

1. Lactobacillus
2. Leuconostoc
3. Pediococcus
4. Weisiella
5. Erysipilothrix

Question 186

Guy comes back from country where there is a measles outbreak and has fever and rash.

a. What 3 diagnostic specimens should be collected and what is one test that should be performed on each?
b. In what time frame should these specimens be collected?

Answer 186

Throat Swab – PCR or Culture for Measles
NP Swab – PCR or Culture for Measles
Blood – IgG, IgM Serology
Urine – PCR or Culture for Measles

b) Within 7 days of the rash onset (14 days for urine)

Question 187

What are 3 non-invasive tests for H. pylori and a disadvantage of each test?

Answer 187

Serology – may detect past infection
Urea breath test – Affected by PPI or bismuth, False negative with GI bleeding
Stool antigen test – Affected by PPI or bismuth, False negative with GI bleeding

Question 188

Your laboratory decides to implement for M100 S23 methods for testing Enterobacteriaceae in terms of ESBL. You now have susceptibility panels that go down low enough to achieve these breakpoints. What 2 major changes will occur by adopting these recommendations?

Answer 188

• There will appear to be more ESBLs due to the lowered break points
• No longer have to confirm ESBL with MAST testing (only for epidemiology or infection control)

Question 189

You isolate an Acinetobacter baumanii that tests resistant to cephalosporins and FQs, but susceptible to Imipenem by your automated susceptibility system.

a. What are 2 methods you can use to confirm imipenem susceptibility?

Answer 189

MIC Method (ETest)
Microbroth Dilution
Disk Diffusion
Agar Dilution

Question 190

What are 3 resistance mechanisms to carbapenems in Acinetobacter species?

Answer 190

• Carbapenemase
• Efflux Pump
• Porin mutation

Question 191

What are 2 side effects of colistin?

Answer 191

Nephrotoxicity

Neurological disturbances

Question 192

What are 2 phenotypic methods to confirm carbapenemases?

Answer 192

1. Modified Hodge Test

2. Disk Inhibition Assay with Meropenem, Boronic Acid, EDTA (Rosco Test)

Question 193

What are 2 factors that may impact susceptibility testing results with daptomycin? What is one body site where daptomycin shouldn’t be reported?

Answer 193

1. Requires calcium in the media
2. There are no disk diffusion criteria
3. There are only MIC values for susceptible (not intermediate or resistant)

Should not be tested for respiratory tract infections

Question 194

You design a multiplex PCR for stool pathogens including norovirus, rotavirus, sapovirus, adenovirus, astrovirus.

a. Which are these requires a reverse transcriptase step?

Answer 194

Norovirus and Sapovirus (the Caliciviruses)

Question 195

What other 2 assays could be done to test for most of the GI viruses?

Answer 195

• Electron microscopy
• Antigen assay
• PCR

Question 196

What are a selective and a non-selective agar used in culturing Legionella? What are 2 limitations of the Legionella urine antigen test?

Answer 196

Selective = BCYE Agar with antibiotics – Cefamandole, Polymyxin B, Ansiomycin (BMPA)
NonSelective = BCYE Agar without antibiotics

Limitations =

1. Only detects Legionella pneumonphila serogroup 1
2. May be negative in the first day of illness
3. May be negative in those with a low burden of disease

Question 197

What is the difference between acid fast and modified acid fast stain. Be specific.

Answer 197

The decolorizer used in each stain is different
Modified Acid Fast uses 0.5-1% H2SO4
Acid Fast uses 3% Acid Alcohol or HCl

Question 198

Patient has anti-HCV+, PCR negative. Provide 5 explanations.

Answer 198

• Level of HCV below the lower limit of detection of the test
• Patient cleared the infection in the past
• Successfully treated for HCV
• False positive antibody test
• False negative PCR assay
• Maternal HCV antibodies in babies
• Passively acquired HCV antibodies from transfusion

Question 199

List 5 requirements for making an antibiogram.

Answer 199

1. Only 1 isolate per patient counted in the antibiogram
2. Only routinely tested antibiotics included
3. Antibiogram is created at least annually
4. Presented as percent of isolates susceptible to the given antibiotic
5. Only use final, verified results
6. Only species with data on >=30 isolates
7. Only diagnostic isolates, not surveillance ones

Question 200

3 most common pathogens in a dog bite to genus level.

Answer 200

1. Pasteurella
2. Streptococcus
3. Staphylococcus
4. Capnocytophaga

Question 201

State 2 recommendations from NACI regarding the use of HPV vaccine in males.

Answer 201

1) Quadravalent HPV vaccine is recommended in males >=9 years old who have sex with men
2) Quadravalent HPV vaccine is recommended in males 9-26 years of age for the prevention of penile, perianal, perineal intraepithelial neoplasias and associated cancers
3) Quadravalent HPV vaccine is recommended in males 9-26 years of age for the prevention of anal intraepithelial neoplasias grade 1, 2, and 3, anal cancer and anogenital warts.
4) Any MSM >27 should be strongly considered

Question 202

Name 2 antiretroviral therapies that interact with PPIs

Answer 202

1) Rilpilvirine

2) Atazanavir

Question 203

Name 1 integrase inhibitor that interacts with CYP3A4

Answer 203

Elvitegravir

Question 204

Name 2 medications that can be used as boosters

Answer 204

1) Ritonavir

2) Cobisistat

Question 205

Name 1 antiretroviral therapy that can cause complications with long term exposure to NSAIDS

Answer 205

Tenofovir

Question 206

5. A patient is 10 days post op after insertion of a prosthetic knee. She develops a fever post for 24 hours. She has a PICC line in place and the surgeon orders it to be removed. Prior to removal the line is functioning well with no erythema or discharge around the site. Follow up cultures are negative in the urine and blood. Tip culture is positive for MSSA. You are consulted from management of a ‘line related infection’.
   a. What 2 things would you advise the surgeon?

Answer 206

Treat for 5-7 days after line removal

If she was bacteremic with the line in then she would need antibitoics for 4-6 weeks

Question 207

List 4 viruses associated with blood borne transmission (Not HIV or Hepatitis)

Answer 207

West Nile Virus
CMV
HTLV
EBV
Rabies

Question 208

TB questions

a. What are 4 indications for the use of pyridoxine with INH?

Answer 208

Pregnancy
Malnutrition
Diabetes
Seizure Disorder
Substance Abuse
Renal Failure

Question 209

Why do you need to counsel women about alternatives to OCP while on antituberculous therapy?

Answer 209

Rifampin induces hepatic microsomal enzymes accelerating the clearance of the OCP.

Question 210

What is the mechanism of action for pyrazinamide causing hyperuricemia?

Answer 210

Inhibits uric acid excretion

Question 211

What 2 tests do you need to follow up for patients on ethambutol?

Answer 211

Visual acuity testing

Red-green color perception testing

Question 212

A patient is presenting with lymphocutaneous ulcers on his forearm. A biopsy was taken and sent to the lab.
a. What treatment would you start if the biopsy showed long gram positive bacilli?

Answer 212

Nocardia:

TMP-SMX 2.5 – 5 mg/kg po of the trimethoprim component twice daily

Question 213

A patient is presenting with lymphocutaneous ulcers on his forearm. A biopsy was taken and sent to the lab.
b. What treatment would you start if the gram stain showed yeast?

Answer 213

Sporothrix:

Itraconazole 200 mg po daily x 2-4 weeks after lesions are resolved

Question 214

A patient is presenting with lymphocutaneous ulcers on his forearm. A biopsy was taken and sent to the lab.

After 48 hours there was no growth on the MAC and pinpoints on the chocolate. Preliminary tests oxidase -, weak catalase +, and urease -. What is the organism?

Answer 214

Fransicella tularensis

Question 215

A pregnant female presents at 12 weeks gestation with a toxoplasma serology positive for IgM.
a. What 2 non-serological test would you perform?

Answer 215

Fetal ultrasound
PCR for Toxo from Amniotic fluid
No amniocentesis before 18 weeks gestation as per SOGC

Question 216

A pregnant female presents at 12 weeks gestation with a toxoplasma serology positive for IgM.
b. What 1 treatment would you start?

c. If it is now at 24 weeks what would the treatment of choice be?

Answer 216

b) Spiramycin 1 g 18h

c) Spiramycin

Question 217

For the following organisms list the latest time Ig can be given as PEP?

a. Measles
b. VZV
c. HBV
d. HAV
e. Rabies

Answer 217

a. Measles
6 days after the exposure (immunoglobulin)
Incubation period for measles is 10 days. Vaccine is live, attenuated. Can not give measles vaccine to pregnant women or those with cell mediated immunity deficits. OK to give to asymptomatic HIV infected kids.
b. VZV
10 days following the exposure (VARiZIg)
Incubation period for varicella (chicken pox) is 14 days
c. Hepatitis B
14 days from a sexual exposure, 24 hours from needlestick, ocular, or mucosal exposure??
Newborns – 12 hours if mom known positive
Newborns – 7 days if mom found after delivery
d. Hepatitis A
14 days (Immunoglobulin)
Indicated for persons 40 years, immunocompromised all ages, and patients with chronic liver diseases. All other people should get the vaccine for PEP instead of immunoglobulin. Note that for Hep A (and measles) its just general immunoglobulin, it’s not specific for the virus.
e. Rabies
Anytime

Question 218

11. With respect to rabies immunoglobulin, state whether you would administer it for the following scenarios:
    a. A man was bit by a raccoon while he was trying to scare it away from his garbage can. The raccoon could not be recovered.
    b. A girl is bit while playing with her uncles dog at a party.
    c. A couple noticed that a bat flew into their cottage house while they were sleeping. There is also a 10 year old son in the cottage.

Answer 218

a. A man was bit by a raccoon while he was trying to scare it away from his garbage can. The raccoon could not be recovered.
Provoked raccoon, not recovered = Yes
b. A girl is bit while playing with her uncles dog at a party.
No, dog is available for monitoring, should be monitored for 10 days for any signs of rabies.
c. A couple noticed that a bat flew into their cottage house while they were sleeping. There is also a 10 year old son in the cottage.
No for the adults only if they had evidence of bite or scratch on their skin.
Yes for the kid because he was an unattended child

Question 219

List 4 scenarios in which you would provide active immunization following a significant exposure.

Answer 219

Hepatitis B – baby born to a known positive mother
Rabies immunization following a bat bite
Hepatits A vaccine if patient is between 12 months and 40 years of age after exposure to hepatitis A
Tetanus immunization along with immunoglobulin
Measles in nonimmune person
Meningococcal within 7 days (daycare, sleeping in same house, respiratory procedures without protection, saliva contact, 8 hours on a plane)
Varicella

Question 220

A woman inquires about varicella vaccination. What are 3 contraindications.

Answer 220

1) Pregnancy
2) Immunocompromised
3) Anaphylaxsis to any components of the vaccine
4) Active tuberculosis

Question 221

For each virus what is the animal reservoir?  
a.	Herpes B 
b.	Sin Nombre virus
c.	Rabies
d.	Chlamydia psittaci
Birds

Answer 221

a.	Herpes B 
Monkey      
b.	Sin Nombre virus
Deer Mouse (Hantavirus)
c.	Rabies
Bats
d.	Chlamydia psittaci
Birds

Question 222

15. A HIV positive female is stable and has been managed on tenofovir, emtricitabine and efavrinez.
    a. She becomes pregnant, what would you suggest for antiviral therapy during pregnancy?

Answer 222

Continue on the same thearpy

Question 223

A HIV positive female is stable and has been managed on tenofovir, emtricitabine and efavrinez.
b. In another scenario the patient is now HIV positive but treatment naïve. What would you treat with?

Answer 223

If not already on therapy would start with Zidovudine-Lamivudine + Lopinavir/Ritonavir
Tenofivir-Lamivudine + Lopinavir/r

Question 224

16. An HIV positive man is now not on any ARV. His CD4 is 865 and VL 2000. He would like to resume sexual intercourse but wanted information on how to be as safe as possible.
    a. Counsel this patient on methods of safer intercourse (3 things)

Answer 224

Use condoms consistently and correctly
Patient could start ARVs to decrease chance of transmission
Partner could use pre-exposure prophylaxis (PrEP) therapy with Emtricitabine + Tenofovir once daily
No intercourse if active lesions (HSV)
Abstain until viral load is negative

Question 225

17. A person comes to clinic because he has just had sex with an HIV positive female.
    a. Provide 2 different regimes for PEP

Answer 225

Non-occupational exposure:

1) Darunavir/r + Tenofovir + Emtricitabine
2) Raltegravir + Tenoforir + Emtricitabine
3) Atazanavir/r + Tenofovir + Emtricitabine

Question 226

Duration of PEP for HIV

Answer 226

28 days

Question 227

A patient with AML with deteriorating respiratory disease.

a. What agent would you use to manage aspergillosis?

Answer 227

Voriconazole (6 mg/kg IV q12 hr x 2 doses, then 4 mg/kg IV q12h)

Question 228

What risk factors will put a patient at highest risk for mould infection?

Answer 228

1) Allogenic Hematopoetic Stem Cell transplant recipient
2) Hematological malignancy with neutropenia
3) Lung Transplant patients
4) Heart Transplant patients
5) GVHD
6) CGD
7) HIV

Question 229

A patient with ALL and a CVC. Blood cultures grow yeast and they are germ tube negative.
a. What 2 different antifungal agents could you start empirically and give mechanisms of action.

Answer 229

Micafungin: Noncompetitive inhibition of the synthesis of 1-3B-D Glucan
Liposomal Amphotericin B: Disrupts fungal cell wall by binding egosterol which leads to pore formation and leakage of cellular contents

Question 230

A patient with ALL and a CVC. Blood cultures grow yeast and they are germ tube negative.
b. List 2 things to follow up with in addition to starting antifungals

Answer 230

Daily blood cultures until documented negative
Ophthalmic exam by an ophthalmologist to look for endophthalmitis even if they don’t have any ocular symptoms
Remove the line

Treatment for candidemia is 2 weeks after blood cultures are negative. Also symptoms should have resolved and in neutropenic patients only d/c therapy after the neutropenia has resolved (ANC >500).

Question 231

2 indications to treat asymptomatic bacteruria

Answer 231

Prior to a transurethral resection of the prostate

Prior to urological procedure that mucosal bleeding is anticipated

Question 232

Name 2 organisms that are thought to be transmitted by aerosols but are not thought to be transmitted person to person?

Answer 232

Francisella tularensis 
Coxiella brunettii
Hantavirus
Leptospirosis
Bacillus antrhasis (can be transmitted with direct skin lesions) – instead say pulmonary anthrax 
LCV

Question 233

What would you expect serologies to be for a chronic coxiella infection?

Answer 233

Phase II titers for IgG >=200 and for IgM >=50
Or document a 4 fold rise by immunofluorescent antibody testing in anti-phase II IgG between acute serum and convalescent serum 3-6 weeks later

Chronic infections would be suggested with an IgG titer to phase I >800, or the peristance of anti phase I IgG>800 6 months after completion of therapy.

Question 234

A veterinarian that was previously well primarily cares for small domestic animals. He presents with fever and fatigue. Has an echo that shows a valvular vegetation.

a. Given his occupation there is a high suspicion for Bartonella. What would the recommended treatment for bartonella endocarditis be according to the IDSA?
b. What other infection would you be considering?

Answer 234

a. Ceftriaxone 2g IV daily x 6 weeks + Gentamycin 1 mg/kg per day q8h x 2 weeks + Doxycycline 100 mg po BID x 6 weeks

If culture confirmed then Doxy x 6 weeks + 2 weeks Gent

b. Q fever

Question 235

A woman travels to Tanzania and climbs Mount Kilimanjaro. She presents with a fever and eschar. List 3 organisms on the differential.

Answer 235

Rickettsia africae
Rickettsia aktari (Rickettsial pox)
Orientia tsutsugamuchi – Scrub typhus

Question 236

A male returns from a trip from Costa Rica. He has an ulcer on his lower leg that appears to be Leishmaniasis.
a. What are 2 methods of making the diagnosis (not molecular testing)? For each method of testing list what stage of the protozoa you are trying to detect.

Answer 236

Staining of tissue biopsy with Wright-Geimsa: Looks for Amastigotes
Cutlure of tissue with Schniders Drisophila Media: Looks for promastigoes

Question 237

3 systemic treatments for leishmaniasis?

Answer 237

Amphotericin B x 14 days
Mitefozine x 30 days
Stiboluconate (Antimony derivative) IM

Question 238

A patient presents with parotitis which appears consistent with mumps.
a. What is the most common cause of bacterial parotitis?

Answer 238

Stapylococcus aureus

Question 239

b. 2 modalities for diagnosing mumps?

Answer 239

PCR - saliva, throat swab, buccal swab, urine, CSF
Serology
Culture

Question 240

c. What are 3 complications of mumps?

Answer 240

Oochitis
Aseptic Meningits
Sensioneural hearing loss
Endocardial Fibroelastosis
Oophritis
Pancreatits

Question 241

27. Patient admitted with fever, headache and meningismus. A CSF was drawn which is neutrophilic, elevated protein and low glucose. Gram stain shows GNDC.
    a. What are 2 things to do immediately?

Answer 241

1) Initiate antibiotics with Ceftriaxone 2g IV x 7-10 days

2) Place the patient on respiratory droplet isolation until 24 hours of antibiotics

Question 242

27. Patient admitted with fever, headache and meningismus. A CSF was drawn which is neutrophilic, elevated protein and low glucose. Gram stain shows GNDC.
    b. It is confirmed as N. meningititis. What 2 things do you need to follow up with?

Answer 242

1) Prophylaxis for close contacts with rifampin 600 mg PO BID x 2 days or Cipro 500 mg po x 1 or Ceftriaxone 250 mg IM x 1. Household or intimate contact, medical personel with contact with oral secretions
2) Vaccination if appropriate (dormatories, military)

Question 243

28. A patient is put on TNF alpha inhibitor for rheumatoid arthritis. She now presents with signs and symptoms of meningitis. CSF cultures are positive for E. Coli and B. fragilis.
    a. Prior to starting the TNF alpha inhibitor what screening test could have been done to prevent this?
    b. What bacterial etiology should be screened for before starting this treatment?
    c. What are 2 viruses (non-herpesviridae) that can be reactivated on this treatment?

Answer 243

a. Strongyloides serology
b. Tuberculosis
c.
Hepatitis B Virus
JC Virus
HPV

Question 244

29. Patient with chromoblastomycosis.

a. What is the name of the cells classically seen on gram stain of the lesion?

Answer 244

Muriform cells (aka sclerotic, Copper Penny or Medlar bodies)

Question 245

29. Patient with chromoblastomycosis.

b. List 3 etiologies

Answer 245

1) Fonsecaea pedrosoi
2) Cladophilophora carrionii
3) Fonsecaea monophora
4) Philophora verrucosa

Question 246

c. List 3 treatment options for a patient with Chromoblastomycosis

Answer 246

1) Itraconazole
2) Terbinafine
3) Liquid nitrogen
4) Surgical Excision

Question 247

30. Patient presents with MRSA bacteremia

a. 2 agents that are approved for MRSA bacteremia?

Answer 247

1) Vancomycin

2) Daptomycin

Question 248

30. Patient presents with MRSA bacteremia

b. An echo was performed and the patient has a vegetation on a prosthetic valve. What agent to add?

Answer 248

Vancomycin

Question 249

31. Diabetic foot that has been unresponsive to courses of Keflex, Cipro and Clinda. Presents to the ER with worsening erythema and discharge around the ulcer, as well as increasing pain.
    a. 2 diagnostic tests to diagnose osteomyeltits

b. In the ER she was started on Cephalexin. The lesion is worsening with necrotic skin at the edge of the lesion. What are 2 things to do to manage this patient?

Answer 249

a.
XRay
Bone and Gallium Scan
Probe to bone
Bone culture

b.

1) Intravenous Antibiotics
2) Debridement
3) Consult Vascular Surgery

Question 250

32. Physician calls you about a patient with chronic fatigue syndrome. He has read articles about Xenotropic murine leukemia virus related virus (XMRV) and it’s links to chronic fatigue syndrome. He wants to start the patient on treatment and asks for your advice on the workup and treatment of XMRV. What would you advice the physician?

Answer 250

No need for work up or treat

Question 251

33. IPAC has made routine investigation in the GI clinic and has found that some of the times the endoscopes are not being brushed off and cleaned prior to disinfection with glutaraldehyde.
    a. What are 2 breeches that have occurred in the GI clinic?

Answer 251

The instruments are not being properly pre-cleaned

The scope is not being cleaned prior to disinfection

Question 252

b. List 3 spaulding criteria and the level of disinfection/sterilization for each class.

Answer 252

1) Critical = Sterilization
2) Semi-Critical = High Level Disinfection
3) Non-Critical = Cleaning with low level disinfection

Question 253

What are the 3 most common infectious causes for a mycotic aneurysm?

Answer 253

1) Staphylococcus aureus
2) Coagulase negative Staphylococci
3) Salmonella species
4) VGS

Question 254

Fidaxomycin

a. Mechanism of action

Answer 254

Inhibits protein synthesis by inhibiting the RNA polymerase

Question 255

b. 2 favorable pharmacodynamics qualities for fidaxomicin

Answer 255

Mainly distributed in the GI tract
Very little excreted by the kidneys
Bacteriocidal

Question 256

c. What is 1 clinical benefit for fidaxomicin?

Answer 256

Less risk for recurrence of C. difficile in patients with non-NAP1 strains

Question 257

36. Your hospital has an outbreak of KPC producing Klebsiella pneumonia. List 6 measures that can be instituted to control and manage the ongoing outbreak.

Answer 257

1) Cohort patients and staff
2) Increased environmental cleaning
3) Perform active surveillance cultures on patients
4) Ensure high levels of hand hygiene compliance
5) Strictly enforce contact precautions
6) Dedicated nursing
7) Dedicated instruments
8) Communicate frequently with hospital staff
9) Archive all potential isolates for typing

Question 258

37. Rates of surgical site infections have been increasing in your institution. You are part of a committee that has been asked to examine methods to improve rates of surgical site infections. What are 4 recommendations to make as part of your ‘bundle’?

Answer 258

1) Hair removal with clipping or depilatories instead of shaving
2) Ensure timely and appropriate administration of prophylactic antibiotics
3) Redose prophylactic antibiotics for long procedures
4) Maximize diabetes control prior to operation if possible
5) Chloroxidine daily washes
6) Chlorohexidine instead of iodine
7) Wound closer without tension
8) Gental retraction

Question 259

38. A 24 year old male presents with fever, hypotension, worsening respiratory distress. A CT shows bilateral opacities (rounded) with a left sided empyema. A week ago the patient had a sore throat. This has now worsened.
    a. List the syndrome and the organism.

Answer 259

Syndrome = Lemierre’s Syndrome
Organism = Fusobacterium necrophorum

Question 260

39. HEV. 2 different types of HEV and provide 1 unique clinical and 1 unique epidemiological association for each.

Answer 260

Endemic – fecal-oral transmission
Sporatic – zoonosis
??? Not sure on this one

Question 261

1. Gram stains:

a. Describe the method

Answer 261

First fix the smear with heat or methanol. Then flood the slide with crystal violet and leave for at least 15 seconds, remove crystal violet with water and flood slide with iodine for at least 15 seconds. Remove the iodine with water and then decolorize the slide with acetone-alcohol for 15 seconds, rinse with water and then flood the stain with counterstain of safranin for at least 15 seconds.

Question 262

4 organisms that don’t stain well

Answer 262

Mycoplasma
Chlamydia 
Treponema
Rickettsia
Coxiella
Legionella
Leptospira

Question 263

b. 2 organisms that tend to overdecolorize

Answer 263

Streptococcus pneumonia
Clostridium clostridiforme
Bacillus species

Question 264

2. What are 2 test that can be done to differentiate a gram positive from a gram negative organism if the stains are equivocal?

Answer 264

1) KOH test using 3% potassium hydroxide
2) Test for cell wall aminopeptidase (in gram negatives) using either GramSure disk or APNA K915 disks.
3) Vancomycin disk diffusion susceptibility testing (Kirby Bauer)
4) CNA plate

Question 265

3. What is the only indication for HPV PCR testing for cervical specimens in Canada?

Answer 265

Women over 30 years of age with ASCUS (atypical squamous cells of undetermined significance) on cytology (until age 69)

Question 266

4. A man on chronic prednisone admitted with fever and worsening cough and SOB. The respirologist decides to do a BAL for work up of possible PCP.
   a. Name 2 stains that can be used for PCP (specifically told not to use NAAT or fluorescence)

Answer 266

Methenamine Silver Stain (Grocott)
Papanicolaou’s Stain
Toluidine blue O Stain
Rapid Geimsa-like Stain
PAS (Periodic Acid Schiff Stain)

Question 267

b. The BAL is positive for PCP, however there is an induced sputum that was sent earlier that was reported as negative. What would lead you to believe that the first test was actually a false negative?

Answer 267

The clinical scenario fits with a diagnosis of PCP.
BAL is more sensitive
In HIV negative patients the sputum is less sensitive

Question 268

5. A man returns to clinic for recurrent mucopurulent urethritis. He was initially seen a few days ago and started on appropriate antimicrobial therapy. You suspect Neisseria gonorrhea.
   a. What specimen would you send and what test would you ask for?

Answer 268

Urethral swab for culture and ask for susceptibility testing

Question 269

b. What is the most common mechanism of resistance to 3rd generation cephalosporins for Neisseria gonorrhea?

Answer 269

Alterations in Penicillin Binding Protein 2 (PBP2) encoded by penA gene. Specifically the presence of a mosaic PBP2 in N. gonorrhea resistant to 3rd generation cephalospsorins.

Question 270

6. A lung biopsy is sent from a patient who is immunocompromised. They are concerned about a fungal infection and have sent for fungal culture.
   a. How would you process this specimen in the lab?

Answer 270

Sample should be sent in a sterile container and kept moist to prevent drying. Sample should be at room temperature and transported to the laboratory as soon as possible. The tissue should be minced and not ground. Tissues pieces should be pressed into the agar so they are partially embedded. 2-4 pieces of tissue per media and no streaking. A small portion of tissue should be ground for microscopy smears. If suspecting H. capsulatum then the tissue should be ground instead.

Question 271

6. A lung biopsy is sent from a patient who is immunocompromised. They are concerned about a fungal infection and have sent for fungal culture.
   b. What are 3 media you would use and provide a rationale for each?

Answer 271

1) Sabarose dextrose agar without antibiotics – supports growth of all fungi, inhibits bacteria
2) Brain Heart Infusion Agar with sheep blood and without antibiotics – Supports the growth of all fungi, and many bacteria. Since this is a sterile site would want an agar without antibiotics as well.
3) Mycosel Agar – contains chloramphenicol, cycloheximide and glucose. Inhibits bacteria and many pathogenic fungi but allows the grows of dimorphic fungi.
Allows growth of all dimorphics and Dermatophytes
Inhibits Cryptococcus, Aspergillus fumigatus, Scedosporium prolificans, Penicillium marneffei, some Candida and most Zygomyces.

Question 272

c. What are 2 media you could use to enhance sporulation?

Answer 272

1) Potato dextrose agar (PDA)
2) Rapid sporulation agar (RSA)
3) Potato flake agar (PFA)
4) Cornmeal Agar

Question 273

7. What are risk categories for the following:
   i. Bacillus anthracis –
   ii. Influenza A H2N2 –
   iii. Hepatitis B –
   iv. Cladophilophora bantania –
   v. Herpes B –

Answer 273

\:
i.	Bacillus anthracis – Risk group 3
ii.	Influenza A H2N2 – Risk group 3
Also the 1918 flu strain
iii.	Hepatitis B – Risk group 2
iv.	Cladophilophora bantania – Risk group 3
Because it can cause serious disease, CNS phaeohyphomycosis.  Infection can be contracted through inhalation.  Handle with extreme care
v.	Herpes B – Risk group 4

Question 274

b. As part of schedule 5 of the health promotion and protection act, what organism is banned from use?

Answer 274

Variola virus (Smallpox)

Question 275

c. A laboratory worker has Shigella dysentery. It is suspected to be lab acquired. What must you do according to this act?

Answer 275

Inform the Minister of Health and provide details of the incident, the pathogen involved and any other information the Minister may require.

Question 276

8. There is a patient with ‘hemorrhagic bullous lesions’ in a peripheral hospital. It has been transported to your lab, nonmotile, nonhemolytic. Gram stain shows large GPB.
   a. What 2 things should you do right away?

Answer 276

Alter the treating physician of a possible diagnosis of anthrax
Transfer the organism into level 3 containment facility

Question 277

b. What 3 tests would you use to identify Bacillus anthracis?

Answer 277

Egg yolk reaction (should be positive)
Penicillin susceptibility (should be penicillin S)
Demonstrate capsule formation with India Ink staining, or McFayden’s stain

It’s also nonmotile and nonhemolytic

Question 278

c. You wish to send the Bacillus anthracis off to the reference laboratory. What are 3 issues you need to do when transporting specimens?

Answer 278

Category A.  
Proper packaging
Wrapped in absorbant material
Primary receptacle that is water proof
Secondary container that is waterproof
Third container (box)
Properly labeled 
Inform receiving lab

Question 279

9. Expected susceptibilities for the following organisms: (Just say S or R)
   a. Staph aureus and penicillin -
   b. Morganella and imipenem –
   c. Stenotrophomonas and Septra -
   d. Burkholderia and colistin -
   e. Klebsiella and ampicillin –

Answer 279

a. Staph aureus and penicillin - Resistant
b. Morganella and imipenem – Susceptible (higher MICs)
c. Stenotrophomonas and Septra - Susceptible
d. Burkholderia and colistin - Resistant
e. Klebsiella and ampicillin – Resistant

Question 280

Antiviral susceptibility testing

a. What is the main difference between phenotypic and genotypic testing?

Answer 280

Phenotypic testing measures viral replication in the presence of antivirals whereas genotypic testing looks for the genes known to cause resistance.
Genotypic is molecular
Phenotypic requires culture

Question 281

b. What are 2 chronic viral infections that resistance testing can only be done by genotype?

Answer 281

Hepatitis C Virus

???

Question 282

c. What are 2 chronic viral infections that can be tested genotypically and phenotypically?

Answer 282

HIV
CMV
HSV

Question 283

11. Viral CPE detection. What are 3 methods to detect viral growth if there is no CPE pattern?

Answer 283

Blind passage
DFA
Hemadsorption

Question 284

A young man presents acutely ill with meningitis. He has recent exposure to fresh water.

a. What are 3 free living amoebas that can cause this syndrome?
b. What is 1 simple test that can be done on CSF to detect the parasite?

Answer 284

a.
Naegleria fowleri
Acanthamoeba
Balamuthia mandrillaris

b. Wet mount of CSF to look for trophozoites

Question 285

The ED and community travel medicine clinic have approached you as they feel the thin smears done for malaria testing are insensitive.
a. What are 2 issues to discuss with the ED/clinic to improve sensitivity?

Answer 285

Ensure that a thick smear is ordered with each thin smear to improve sensitivity
Have the ED/clinic order 3 sets of smears on patients suspected of having malaria at 12 hour intervals

Question 286

The ED and community travel medicine clinic have approached you as they feel the thin smears done for malaria testing are insensitive.

b. What are 2 issues in the lab you should look at to improve sensitivity?

Answer 286

Implement a rapid malaria test as well
Ensure training of technologists is adequate
Proficiency testing

Question 287

c. Name 2 different tests for malaria testing and for each give 1 advantage.

Answer 287

Microscopy with thin smears – Advantage = able to speciate the organism and determine a percent parasitemia
Immunochromographic rapid test – Advantage = fast turn around time, easy to perform, no specialized equipment
Fluorescent DNA/RNA stains – Advantage = rapid
NAAT = Advantage – Increased sensitivity

Question 288

b. 2 contraindications for IGRA testing

Answer 288

To diagnose Active TB

When serial testing is required (ex Health care setting)

Question 289

16. Chart about implementing a new antimicrobial susceptibility test. Given data from the gold standard and how the new test compares to the gold standard.
    a. Calculate very major, major and minor errors. Also categorical agreement.

Answer 289

Very Major = Resistant isolate called sensitive
Major = Sensitive isolate called resistant
Minor = Sensitive or resistant isolate called intermediate or an intermediate isolate called sensitive or resistant.
Categorical agreement = Percentage of agreement between the categories Sensitive, Intermediate, and Resistant between the new test and the gold standard. (Number of categorical matches / Number of samples tested) x 100

Question 290

b. What are the accepted errors for introducing a new test (%VME, ME)? What is the minimum % categorical agreement required of the new test?

Answer 290

% Very Major Errors = ≤3%
% Major Errors = ≤3%
Minimum categorical agreement required = ≥90%
Combined Major Error and Minor errors should be ≤7%

Question 291

17. Allogenic BMT patient recently treated for bacterial pneumonia. Recently travelled for several months through the United States. Now presenting with meningitis. CSF is sent to the lab for testing.
    a. What are 2 reasons for each of the following scenarios?
    i. Positive india ink/ Negative cryptococcal Ag test

Answer 291

1) True cryptococcal infection: False negative crytococcal antigen test due to prozone effect
2) True cryptococcal infection: False negative cryptococcal antigen test due to low titers of cryptococcal antigen.
3) False positive india ink due to WBC instead of the antigen.

Question 292

17. Allogenic BMT patient recently treated for bacterial pneumonia. Recently travelled for several months through the United States. Now presenting with meningitis. CSF is sent to the lab for testing.
    a. What are 2 reasons for each of the following scenarios?
    ii. Negative India ink / Positive cryptococcal Ag test

Answer 292

1) True cryptococcal infection: False negative India ink stain due to low sensitivity of this staining method
2) No cryptococal infection: False positive cryptococcal Ag test due to rheumatoid factor, sinuresis fluid, Trichosporin, Capnocytophaga

Question 293

17. Allogenic BMT patient recently treated for bacterial pneumonia. Recently travelled for several months through the United States. Now presenting with meningitis. CSF is sent to the lab for testing.
    b. What antifungal should you not use and give 2 reasons why

Answer 293

An echinocandin (ie micafungin, caspofungin):

1) Cryptococcus and dimorphic fungi are resistant to echinocandins
2) Echinocandins do not get into the CSF

Question 294

17. Allogenic BMT patient recently treated for bacterial pneumonia. Recently travelled for several months through the United States. Now presenting with meningitis. CSF is sent to the lab for testing.
    c. In 5 days the lab is growing a white mycelia on culture. 2 possibilities?

Answer 294

Coccidioides immitis

Histoplasma capsulatum

Question 295

18. Brucella melintensis identified in the lab

a. What 4 phenotypic tests are level 2 labs allowed to do for preliminary workup of Brucella (can not use gram stain)?

Answer 295

1) Oxidase - positive
2) Catalase - positive
3) Urease - positive
4) Positive slide agglutination reaction with specific B. abortus and/or B. melitensis antisera
5) Nitrate – positive

Question 296

b. What are 4 things you can do in the lab to prevent lab acquired transmission of Brucella melintensis?

Answer 296

1) Tape the plates
2) Perform all work on the culture in a Class II or higher biological safety cabinet
3) Label plates as potential Brucella
4) Do not work up the specimen, instead refer to a reference laboratory
5) Slow growing gram negative bacilli should be referred out if suspiction is high
6) Wash hands
7) Avoid any methods that could generate aerosols

Question 297

19. List 4 recommendations for analyzing and preparing antibiograms as per CLSI?

Answer 297

1) Analyse and present a cumulative antibiogram report at least annually
2) Include only final, verified test results
3) Include only species with testing data for ≥30 isolates
4) Eliminate duplicates by including only the first isolate from a patient
5) Report % susceptible and do not include intermediates
6) Only report drugs from routine susceptibility testing, not special requests

Question 298

hat are 4 antibiotics that are not recommended for routine testing on CSF as per CLSI?

Answer 298

Ciprofloxacin (Fluoroquinolones)
Tetracycline (Tetracylcines)
Azithromycin (Macrolides)
Clindamycin
Cefazolin (1st and 2nd genearation Cephalosporins except Cefuroxime IV)
Cefoxotin, Cefotetan (Cephamycins)
Agents administered only by the oral route

Question 299

21. What is the method described by CLSI to confirm a KPC? What is 1 example of a false positive using this method?

Answer 299

Modified Hodge Test
False positive:
- Different type of carbapenemase other than KPC which would also destroy the ertapenem in the agar and allows the Ecoli to grow
- CTX-M and AmpC hyperproduction

Question 300

a. What is a chromosomal carbapenemase produced by Enterobacter cloacae that is resistant to carbapenems but susceptible to cephalosporins?

Answer 300

OXA or SME

Question 301

22. 3 nucleic acid amplification methods besides PCR?

Answer 301

1) Strand displacement assay (SDA)
2) Transcription Mediated Amplification (TMA)
3) LAMP (Loop Amplification)
4) NASBA (Nucleic Acid Sequence Based Amplification)
- RNA to cDNA with reverse transciptase, degrade RNA,
add RNA polymerase and make new RNA

Question 302

23. 4 level 3 organisms that are endemic to at least 1 region in Canada? (need to include 1 bacteria, 1 virus, and 1 fungus)

Answer 302

1) Mycobacterium tuberculosis
2) Histoplasma capsulatum
3) Blastomyces dermatitidis
4) West Nile Virus
5) HIV
6) Brucella
7) Coxiella
8) Rabies

Question 303

24. Your lab is using African Green Monkey kidney cells for viral culture. There is a request for enteroviral culture. The sample inoculated with the patients sample is already showing CPE after 1 day. On examination of other uninnoculated cells there is already CPE. On EM it looks like a herpesviridae. What virus is causing the CPE?

Answer 303

Herpes B Virus (came from the monkey cells)

Can be transmitted to lab workers

Question 304

25. A streptococcus pyogenes isolate is tested as resistant to penicillin. What are 5 things you can do to verify this result?

Answer 304

1) Check for transcription errors, contamination, or defective panel, plate or card
2) Check previous reports on the patient to determine if the isolate was encountered or confirmed earlier
3) Repeat organism ID and AST with initial method to confirm they reproduce
4) Confirm organism ID with second method performed in house or at a reference lab
5) Confirm AST with a second method (in house or referecene lab)

Question 305

26. MALDI-TOF

a. 3 bacteria or bacterial groups that the MALDI-TOF has trouble identifying

Answer 305

1) Streptococcus pneumonia
2) Shigella species
3) Neisseria gonorrhea
4) Aeromonas (can’t speciate it)
5) Acinetobacter complex differentiation

Question 306

26. MALDI-TOF

b. 1 way in which these limitations can be improved

Answer 306

To improve it could look at different types of extraction methods, look at a broader range of protein sizes
Use a different matrix
Extraction procedure

Question 307

27. 4 ways to differentiate Staphylococcus and Micrococcus in the lab

Answer 307

1. Bacitracin - Micro S, Staph R
2. Modified Oxidase - Micro Pos, Staph Neg
3. Furazolidone - Micro R, Staph S
4. Lysostaphin - Micro R, Staph S
5. Strict Aerobe - Micro Yes, Staph No
6. Acid from glycerol aerobically - Staph Yes, Micro No

Question 308

28. Administrators tell you that you need to cut costs in the lab by $50,000. You review the urine culture bench in an attempt to streamline work up. The technologists ask you how to work up the following organisms further.
    a. GNB, Ox negative, not swarming, beta hemolytic

b. GNB, Ox negative, swarming, Indole positive
c. GPC, catalase negative, PYR positive

Answer 308

a. GNB, Ox negative, not swarming, beta hemolytic
Indole test, if positive call E.Coli
b. GNB, Ox negative, swarming, Indole positive
No further workup, Identify as Proteus vulgaris
c. GPC, catalase negative, PYR positive
If Beta heme and greater than 1 mm, Identify as Enterococcus

Question 309

29. For Staphylococcus aureus what are 2 different ways to test for Beta lacatamse production?

Answer 309

1) Penicillin zone edge test – Use a 10 U penicillin disk with standard disk diffusion procedure. If the edge of growth around the disk is sharp (cliff) it’s B-lactamase positive. If it’s fuzzy (beach) it’s negative.
2) Nitrocefin-based test – Perform the test from growth taken from the zone margin surrounding a penicillin or cefoxitin disk.

Question 310

30. Isolate in the lab that is GNB. On TSI there is an alkaline slant with scant production of H2S. It is citrate negative, lysine positive and urease negative.
    a. 3 antigens that you would test and briefly describe each

Answer 310

O Antigen – Heat stable, Somatic antigen
H Antigen – Flagellar antigen
Vi antigen – Heat labile Capsular polysaccharide

Question 311

b. 2 difficulties with serotyping Salmonella

Answer 311

1) The O antigen may initially test negative if the Vi antigen is positive due to the Vi antigen blocking the binding of antibodies against the O Ag. Need to boil the sample to destroy the Vi antigen so that the O antigen can then test positive with Group D.
2) The strain may be rough and not make complete O antigens
3) The strain may be mucoid and not agglutinate with any O antisera

Question 312

31. There is concern of a patient in the ICU with novel coronavirus. The physician sends a respiratory specimen requesting molecular testing for viruses, including novel coronavirus.
    a. 5 routine precautions you can do in the lab to protect the lab workers during the processing/culturing of molecular respiratory samples?

Answer 312

1) Work in a BSC Level II
2) Wear gloves
3) Wear a lab coat
4) Proper waste disposal
5) Hand hygiene

Question 313

34. Current algorithm for intestinal parasites includes direct smears as well as concentration and iron hematoxylin stain. Name 4 clinically significant intestinal parasites that could be missed with this algorithm and 1 stain for each that you would use for them.

Answer 313

Isospora – Acid Fast Stain
Cyclospora – Acid Fast Stain
Microsporidium – Modified Trichrome Stain
Cryptosporidium – Acid Fast Stain

Question 314

35. The center that you are in has decided on a pre-emptive approach to invasive aspergillus. They are currently routinely testing post transplant patients with Galactomannan.
    a. What are 2 other fungi that can be positive on the galactomannan assay?

Answer 314

1) Penicillium species
2) Histoplasma capsulatum
3) Blastomyces dermititidis
4) Paeciliomyes
5) Alternaria
6) Fusarium

Question 315

b. What would be 2 reasons why adding the B-D-glucan with galactomannan would be beneficial?

Answer 315

1) Increase sensivity for Aspergillus

2) Aid in the diagnosis of a fungal infection that is not aspergillus (positive B-D glucan, negative GM)

Question 316

36. A patient is awaiting a kidney transplant. He is EBV negative. A donor kidney is available and the donor’s serology is VCA IgM negative, VCA IgG pos, and EBNA pos.
    a. Interpret the serology

Answer 316

Prior infection with EBV
VCA IgM– Appears at clinical presenation, gone in 4-8 weeks
VCA IgG– Appears at clinical presentation, lasts lifelong
EBNA – Appears 3-4 weeks after onset, lasts lifelong

Question 317

b. What are the clinical implications of transplanting this kidney into an EBV negative host?

Answer 317

EBV positive donor, EBV negative recipient.
The recipient will be at increased risk post transplant lymphoproliferative disorder (PTLD). He will require routine testing for EBV viral load. One regime may be monthly monitoring for 3-6 months then every 3 months for 1 year. If he is found to have an increasing viral load immunosuppression may be decreased or rituximab started.

Question 318

b. What are 2 clinical indications for the use of CMV PCR to diagnose active infection?

Answer 318

1) To diagnose congenital CMV infection
2) CMV in the CSF to diagnose encephalitis
3) Aqeuous or vitreous humor for CMV retinitis
4) CMV donor positive, recipient negative transplant patients

Question 319

38. There is an MRSA cluster in neonatal nursery.

a. What are 2 outbreak patterns that could be suggestive of common source infection?

Answer 319

1) Point source outbreak – rapid peak with slower decline

2) Continuous common source – slow peak and then plateau with slow decline

Question 320

b. 2 phenotypic and 2 genotypic methods to type MRSA

Answer 320

Phenotypic: 
Phage typing
Susceptibilities
Capsule serotyping
MALDITOF

Genotypic: 
PFGE
MLST
Ribotyping
Single Locus Sequence Typing
Multiple Locus Variable Number Tandem Repeat Analysis

Question 321

39. GP recently vaccinated a patient for Hepatitis B. He accidently sends Hepatitis B serology 2 days after. HBsAg pos, HBsAb neg, HBcAb total neg, HBcAb IgM neg. Interpret.

Answer 321

No previous infection with Hepatitis B
Serology consistent with recent vaccination
Patient is not yet immune to hepatitis B virus

Question 322

40. A child was recently vaccinated for influenza (few days ago). He has been well but has had mild rhinorrhea. NPW positive for influenza A, influenza B and adenovirus. You review the controls and both negative controls were OK, and multiple other clinical samples on the run were negative. What is the most likely explanation?

Answer 322

The child received the intranasal live vaccine for influenza that contains both influenza A and influenza B which explains the positive flu A and flu B PCR results. The child is infected with adenovirus. Adenovirus is causing his mild rhinorrhea.

Question 323

41. Name 4 viral etiologies of gastroenteritis and 2 methods to detect them.

Answer 323

1) Rotavirus
2) Norovirus
3) Adenovirus
4) Astrovirus

Detect via electron microscopy or PCR of stool samples. Also could use antigen detection.

Question 324

42. 4 reasons for a patient to have Anti-HCV Ab positive but HCV PCR negative.

Answer 324

1) Completed successful treatment of HCV infection, sustained virological response
2) Currently on HCV treatment, rapid virological response
3) HCV Infection with low levels of HCV RNA
4) False positive Anti-HCV Ab test
5) Maternal Ab if it’s a baby
6) Past infection that cleared spontaneously

Question 325

43. A homeless man is admitted to hospital with fever. Blood and urine cultures negative. Blood film show tiny, thin coiled organisms.
    a. What is the organism?

Answer 325

Borrelia recurrensis

Question 326

b. What are 2 vectors for Borrelia recurrences?

Answer 326

1) Body Louse

2) Head lice

Question 327

44. A Filipino man with peritonitis. Bacterial cultures are negative and you are beginning to suspect TB.
    a. What are 2 specimens you would send for work up of TB peritonitis?

Answer 327

Ascites fluid
Peritoneal biopsy
Send the ascites fluid for an Adenosine Deaminase (specific for TB)

Question 328

b. What are 2 steps in processing normally sterile sites for TB?

Answer 328

Concentrate fluids by centrifugation

Grind tissues then plate directly to media

Question 329

34. Expired reagents – 2 things to do; 4 things to do when starting a new lot of reagents

Answer 329

1. Dispose of reagents safely
2. Identify if they were used for any testing after expiration date and verify those results

Starting a new lot:

1. Visually inspect reagents for any damage or leakage
2. Check expiry dates
3. Label with contents, concentration, storage requirements, date prepared and expiration date
4. QC the reagents

Question 330

35. New test for GBS not approved by Health Canada. Clinician wants you to run it for a woman in labour with ever and unknown GBS – 2 pieces of advice for clinician.

Answer 330

1. The lab is not able to give results from unapproved tests
2. The test has not been verified or validated in the laboratory, therefore results can not be reported
3. Follow protocol for unknown GBS status

Question 331

Cause and treatment of STI related epididymitis

Answer 331

Cause = Chlamydia trachomatis or Neisseria gonorrhoeae
Treatment = Ceftriaxone 250 mg IM x 1 + Doxycylcine 100 mg po BID x 10 days

For other bacteria (enterics), usually older men: Levofloxacin 500 mg PO daily x 10 days

For MSM: Ceftriaxone 250 mg IM x 1 + Levofloxacin 500 mg PO Daily x 10 days

Question 332

Mechanism of action of antifungals and their intrinsically resistant fungi

Answer 332

Ampho B = binds to egosterol and disrupts fungal cell membrane, leakage of intracellular contents
Echinocinins = Inhibits Beta 1,3 beta-D-glucan synthase (enzyme responsible for polysacc formation of the cell wall
Azoles = interferes with egosterol synthesis, increased cell permeability and leakage of contents

Resistance to polyenes = Candida lustaniae, Aspergillus teres, Scedosporium apiospermum
Vorconazole = Zygomyces, Sporothrix
Itraconazole = Scedosporium, Zygomyces
Fluconazole = C. krusei, Sporothrix, Aspergillus, Scedosporium, Demateacious fungus, Zygomyces
Posaconazole = None
Echinocandins = C. neoformans, Trichosporon, Fusarium, Zygomyces, Dimorphics, Scedosporium

Question 333

Indication for starting ARVs not related to CD4, symptoms or OI

Answer 333

Pregnancy
Decrease risk to negative partner
Acute infection
HIV associated nephropathy
HIV RNA >100,000
Hepatitis B or C Coinfection
Age >50 
High Cardiovascular risk or Cardiovascular disease

Question 334

Standard indicators for bacteremia in HD patients

Answer 334

Fever, chills
Purulence at the insertion or exit site
Letheary, altered LOC, hemodynamic instability, hypothermia, acidosis

Question 335

VZV complications in BMT

Answer 335

Cutaneous dissemination
Pneumonitis
Meningoencephalitis
Hepatitis
Pancreatitis

Question 336

Why add doxy to onchocerciasis

Answer 336

It treats Wolbachia which is an endosymbiotic bacteria that lives within in Oncocercas volvulans. Important in the filaria’s fertility and reproduction. Treating with Doxy decreased the number of wolbachia and microfilaria but has no effect on the adult worms.

Question 337

What is the treatment for Onchocerciasis?

Answer 337

Rx for Onchocercisis is:
Doxy 200 mg/day x 6 weeks and then
Ivermectin 150 mcg/kg po for a single dose and consider retreatment every 3-6 months until asymptomatic. Ivermectin only kills the microfilaria not the adults.
DEC is contraindicated for the treatment of Onchocerciasis.

Question 338

Disease with water exposure (fresh water lake, adventerous run, etc)

Answer 338

Leptospira

Others: Aeromonas, Free Living Ameobas, Schistosomiasis

Question 339

Abx for severe c diff

Answer 339

First episode severe = Vancomycin 125 mg po QID x 10-14 days
Complicated Severe = Vancomycin 500 mg po with Metronidazole 500 mg IV q8h
Severe = Age >60, WBC >15, Increased serum Cr >=1.5 x normal.
No hard fast rules, left up to clinical judgement

Question 340

Resistant Klebsiella from india – mechanism

Answer 340

Carbapenemase – Metalo-beta-lactamase (NDM1)

Question 341

Congenital syphilis - 2 early & 2 late symptoms in child.

Answer 341

Early = Low birth weight, HSM, LAN, Snuffles, Rash, Jaundice
Late = Facial features (frontal bossing, saddle nose, protuberant mandible), keratitis, sensioneuronal hearing loss, hutchinson's teeth, anterior bowing of the tibia, seizures, intellectual disability

Question 342

When is maternal treatment inadequate

Answer 342

Maternal treatment is inadequate if mother was treated <4 weeks before birth, or had a treatment with nonpenicillin agent, or evidence of maternal reinfection, inappropriate dose, no documentation of maternal treatment, maternal titres did not decrease 4 fold after treatment for early syphilis or did not remain stable or low for late syphillis

Question 343

5 AE of nitrofurontoin

Answer 343

a. Hepatic reactions
b. Optic neuritis
c. Peripheral neuropathy
d. Pulmonary toxicity
e. Hemolytic anemia
f. Renal impairment
g. Antibiotic associated diarrhea

Question 344

4 serotypes covered in new pneumococcal 13 vaccine not found in PCV 7

Answer 344

a. 19A
b. 1
c. 3
d. 5
e. 7F
f. 6A

Question 345

Treament options for stenotrophomonas

Answer 345

Trimethoprim/Sulfamethoxazole
Levofloxacin
Ceftazidime
Minocyline
Chlormaphenicol
Ticarcillin/Clavulinate

Question 346

Complications and treatment for pseudomonas mastoiditis

Answer 346

Sigmoid sinus thrombosis, intracranial abscess, skull based osteo, mastoid abscess

Ceftazidime 2 g IV q8h x 4-6 weeks
Ciprofloxacin 750 mg po BID x 4-6 weeks

Question 347

3 factors to monitor for when inserting a central line, and 3 for maintaining

Answer 347

To monitor: Hand hygiene, draping the patient

Maintaining: Wipe port with an appropriate aseptic prior to access, use sterile devices to access the port, ???

Question 348

indications to wash hands

Answer 348

When visilbly soiled
Prior to touching the patient or patients environment
Before putting gloves on
After removing gloves
After touching a patient or patient environment
Before clean/aseptic procedures

Question 349

treatment of viridans strep IE w/ MIC =1

Answer 349

This is actually intermediate (0.25-2) by the CLSI (>4) but the IDSA calls this resistant (>0.5)
Treat like enterococcus IE:
Native valve = Pen G 18-30 million U q24h IV divided q4h x 6 weeks + Gentamycin 3 mg/kg q24 hours in 1 dose x 6 weeks
4 weeks if native valve and sypmtoms less than 3 months
6 weeks of native valve and symptoms <3 months, or prosthetic valve

Question 350

6 indications for surgery for IE

Answer 350

a. Persistent vegetation despite systemic antibiotic
b. Anterior mitral valve leaflet vegetation, esp if >10 mm
c. >=1 embolic event in first 2 weeks of therapy
d. Aortic or mitral insufficiency with signs of ventricular failure
e. Heart failure unresponsive to medical Rx
f. Valve perfortation or rupture
g. New heart block
h. Large abscess or extension of abscess despite appropriate antimicrobials
i. Persistently positive blood cultures >5-7 days
j. Infection with a difficult to treat pathogen (fungi, highly resistant)

Question 351

Treatment for invasive aspergillus and 2x AE

Answer 351

Treatment = Voriconazole 6 mg/kg IV q12h x 1 day, then 4 mg/kg IV q12h
Adverse Events of Voriconazole = Visual toxicity and hallucinations, photosensitivity skin rash, renal impairment

Question 352

4 types of zygomycetes

Answer 352

a. Mucor
b. Rhizomucor
c. Rhizopus
d. Cunninghamella
e. Absidia (Lichtheimia)
f. Saksenaea
g. Apophysomyces
h. Scencephalastrum
i. Bacidiobolus

Question 353

2 common HIV resistant mutations –P

Answer 353

a. M184V mutation of the reverse transcriptase – NRTIs (lamivudine, didanuzine, abacavir). Hypersus to AZT, Tenofovir, Stavudine
b. Q151M mutation of the reverse transcriptase – All NRTIs except Tenofovir
c. K103N – NNRTI – Efavrinz, Neverapine
d. K65R – Tenofovir (increased sus to AZT)
e. L90M – All protease inhibitors
f. TAM mutations (Thymadine analogues) – resistance to AZT, Tenofovir, and Stavudine

Question 354

Which vaccine contains porcine circovirus

Answer 354

Rotavirus vaccine – Rotatrix and Rotateq

Question 355

indications for RSV monoclonal antibodies

Answer 355

a. <=28+6 weeks gestation who are less than 12 months old at the start of RSV season

Question 356

Swimming in Lake victoria -> fever HSM eosinophilia -> name

condition and 2 bugs

Answer 356

Schistosomiasis (Katyama Fever)

1. Schistosoma mansoni
2. Schistosoma japonicum

Question 357

Yeast w/ arthroconidia in BMT patient. Name bug and treat

Answer 357

Trichosporon

Treatment = azole – Voriconazole 6 mg/kg IV q12h X 1 day, then 4mg/kg q12h.

Question 358

4 fungi with arthroconidia

Answer 358

Trichosporon, Geotrichum, Coccicioides, Malbrachea, Hormograchiella, Arhrographia, Geomyces, Neoscytalidium

Question 359

4 VFs of pseudomonas

Answer 359

a. Pili – adhere to cell surfaces, biofilm, motility
b. Pyoveriden – compete with host proteins for iron chelation
c. Pyocyanin – reacts with oxygen to form oxygen radicals causing tissue damage
d. Flagella – motility, biofilm, adherence
e. Quarum sensing molecules – cell to cell communication
f. LPS - Endotoxin
g. Secretory systems
i. Type 1 – alkaline protease (inhibits fibrin formation)
ii. Type 2 – exotoxin A, phospholipase C, protease IV, elastase
iii. Type 3 – Directly injects exotoxin (Exo U, Y, S, T) into cell cytoplam

Question 360

Acute EBV complications in immunocompetent

Answer 360

Splenic rupture
Airway obstruction from massive lymphoid hyperplasia
Rash following ampicillin, amoxicillin, or penicillin
Hemolytic anemia
Neurologic – Encepahlitis, GBS, transverse myelitis, optic neuritis

Question 361

treatment options for resistant acinetobacter

Answer 361

Ticarcillin-Clavunlinate
Doxycycline
Colistin
Meropenem
Tigecycline (no interpretive criteria) – does not work for Pseudomonas

Question 362

risk factors to get worse dengue infections

Answer 362

• Previous infection with a different dengue serotype
• Children <1 year old with circulating maternal antibodies
• Elderly

Question 363

5x nonstrep bacterial causes of pharyngitis

Answer 363

a. Fusobacterium necrophorum
b. Archanobacterium haemolyticum
c. Corynebacterium diptheriticum
d. Neisseria gonorrhoeae
e. Mycoplasma pneumonia
f. Syphillis

Question 364

indications for starting HBV treatment

Answer 364

• Compensated cirrhosis with Hep B DNA >2000 IU/mL with any ALT
• Decompensated cirrhosis with detectable Hep B DNA with any ALT
• Acute liver failure
• Clinical complications of cirrhosis
• Prevention of reactivation of chronic Hep B during immunosuppression or chemotherapy

Question 365

33. • cause of increased alts in HBV/HIV pt

Answer 365

Discontinuation of tenofovir, lamivudine or emtricitabine can result in an acute exacerbation of hepatitis

Question 366

indications for PCV13 vaccine

Answer 366

Immunization of children 6 weeks – 17 years of age
Adults with HIV, HSCT, Immunosuppressed
>=50 years old (UpToDate, but NACI doesn’t recommend >65)
Splenectomy – First give PCV13 then 8 weeks later give PSV23, with a PSV23 booster 5 years later

Question 367

35. • HIV pt w/ MAC: treatment

Answer 367

Clarithromycin 500 mg po BID + Ethambutol 15 mg/kg/day + Rifabutin 300 mg po q24h

Question 368

PEP treatment for TB exposure

Answer 368

For adults and older children = no treatment, repeat TST in 8 weeks
Child <=5 years = INH 10 mg/kg/day for 3 months then repeat TST, if negative – stop. If positive continue INH for 9 months total
Neonate = INH 10 mg/kg/day for 3 months, then repeat TST. If repeat is negative, CXR is normal and mother is smear negative. If repeat TST positive, or CXR abnormal then INH + RIF for total of 6 months

Question 369

complications of vori

Answer 369

• Arrythmias/QT prolongation
• Dermatological - Photosensitivity, skin malignancies, Steven Johnsons
• Hepatic toxicity
• Visual effects
• Renal toxicity
• Skeletal effects (fluorosis, periostitis)
• Pancreatitis

Question 370

4 false-pos of crypto latex, including 2 biological

Answer 370

1) Rheumatoid factor present in the sample
2) Cross reaction with Trichosporon asahii
3) Specimen was placed in an anerobic transport vial
4) Sample was exposed to soap or disinfectant
5) Cross reaction with Capnocytophaga canimorsum
6) Hydrox-Ethyl Startch (from colloids)
7) Malignancy
8) Rothia bacteremia

Question 371

HBV core Ab positive, and surface ab/ag neg: 4 BIOL reasons and how to resolve

Answer 371

a. Window period between sAg and sAb, do HBV DNA test
b. Undetectable sAb level due to declining levels after years of infection
c. Undetectable sAg level due to low level after years of infection
d. False positive core Ab
How to resolve – repeat the test, Hep C IgM, HepB DNA PCR

Question 372

3 QI unique for Blood cultures

Answer 372

a. Contamination rate
b. Percent of positive cultures
c. Volume of blood obtained
d. Adequate number of bottles

Question 373

Strep bovis vs enterococcus, meds for IE

Answer 373

Strep bovis:
Pen G 12-18 million U divided in 4-6 doses x 2 weeks
PLUS
Gentamycin 3 mg/kg q24 hours x 2 weeks,

Enterococcus:
Pen G 18-30 million U/24 hrs divided in 6 doses x 4-6 weeks
PLUS
Gentamycin 3 mg/kg/24hr divided in 3 doses x 4-6 weeks

Question 374

neg neg pos AFB smear for pt who is on Rx. Rationale

Answer 374

Drug resistance
Dead organism
Adherence
Drug-drug interactions
False positive
NTM in the smear

Question 375

whats WHMIS and 3 things the lab does about it

Answer 375

Workplace Hazardous Materials Information System
Canada’s national hazard communication standard
All laboratory employees require WHMIS training
Have MSDS available

Question 376

hazard signage

Answer 376

Class A = Compressed Gas
Class B = Flammable and Combustable material
Class C = Oxidizing Material
Class D =
1.	Materials causing immediate and serious toxic effects
2.	Materials causing other toxic effects
3.	Biohazardous infectious materials
Class E = Corrosive Material
Class F = Dangerously Reactive Material

Question 377

4 reasons for RPR- TPPA+ results

Answer 377

a. Prior syphilis (treated or untreated)
b. Early primary syphilis
c. Prozone effect of RPR (false negative due to high antibody content)
d. Infection with a non-venereal syphilis (endemic syphilis, yaws, pinta)
e. False positive TP-PA result due to nonspecific interactions
f. Tertiary syphilis

Question 378

5 pediatric GI viral illness, limitations of EM, which ones are non-culturable

Answer 378

a. Rotavirus – Group A is culturable, but difficult.
b. Norovirus (Caliciviridae family) – non culturable
c. Adenovirus - Culturable
d. Astrovirus – Culturable
e. Sapovirus (Caliciviridae family) – non culturable

EM limitations – concentration of virus must exceed 10^6 to 10^7/gram of stool which is the lower level of detection, low viral burden may be missed, requires specialized microscope, requires trained individuals.

Question 379

2 protoza treatable w/ SXT, and stain used

Answer 379

a. Cyclospora cayetanensis – Modified Acid fast stain
b. Isospora belli – Modified Acid fast stain
c. Toxoplasmosis gondii – Geimsa stain
d. Acanthamoeba – Modified Field’s Stain or Calcoflour white stain with fluorescent microscopy or trichrome stain

Question 380

56. • hookworm vs strongyloides

Answer 380

Hookworm - Large buccal cavity, Inconspicuous genital primordium, Tapered tail
Strongiloides - Short buccal cavity, Prominent genital primordium, Notched tail

Question 381

4 urease positive yeasts

Answer 381

a. Cryptococcus species
b. Trichosporon species
c. Rhodoturula species
d. Sporobolomyces salmonicolor
e. Candida krusei
f. Candida lipolytica

Question 382

GPC resistant to vancomycin

Answer 382

1. Leuconostoc species
2. Pediococcus species
3. Weissella confusa

Question 383

gene targets for PCR for MRSA, Cdiff, Flu, VRE

Answer 383

MRSA = mecA gene and nuc gene (the nuc gene looks that it’s Staph aureus)
C. diff = tcdB gene (toxin B)
Flu = matrix gene
VRE = vanA and vanB genes

Question 384

3 space requirements for a PCR lab

Answer 384

Reagent preparation room
Sample preparation room
Amplification room

Question 385

2 requirements for PCR pipettes

Answer 385

Designated pipettes for each area of the lab (the 3 different rooms)
Aerosol resistant pipettes
Calibrated 2 times per year
Cleaned every 3 months

Question 386

precautions for UV & handling ethidium gels

Answer 386

Ethidium gels – gloves, fume hood, face shield, proper disposal
UV – Self contained UV imaging system

Question 387

2 culture media for campy

Answer 387

• Charcoal cefoperazaone dexoycholate agar
• Charcoal based selective media
• Campylobacter blood agar plate (brucella agar base, sheeps blood, vanco, trimethoprim, polymyxin B, ampho B and cephalothin)

Question 388

3 incubation conditions for campylobacter

Answer 388

• 42 degrees celcius (to supressed other GI growth and jejuni prefers 42 degrees, fetus only grows at 37 degrees)
• Microaerophilic
• 5-7% O2, 5-10% CO2, 80-90% N2

Question 389

6 culture neg IE

Answer 389

1. Coxsiella brunetii
2. Bartonella spp.
3. Tropheryma whipelli
4. Brucella spp.
5. Chlamydia species
6. Legionella species
7. Non-candida fungi
8. Rickettsia

Question 390

mumps specimen types, max duration, isolation duration,

Answer 390

Specimen types = buccal swab, throat swab, saliva, urine, CSF
Max duration = 9 days for buccal, throat, saliva
14 days urine
Acute serology = 7 days, Conval = 7-10 days post acute
Incubation period of 18 days, short prodromal illness, with parotitis first unilateral then bilateral within 2-3 days, followed by aseptic meningitis. Men can have orchitis 4-10 days after parotitis.
Isolation duration = 5 days after onset of parotitis, droplet isolation

Question 391

HIV point of care test vs lab comparison of discrepent results and
advantage of POC

Answer 391

POC is rapid
Does not have to be done in a lab setting
Increased access to testing for some patients
Earlier decisions can be made regarding treatment

Question 392

3 resistant mechanism for MDR pseudomonas against meropenem and drug options

Answer 392

1. Porin mutation to decrease uptake of meropenem (OprD)
2. Carbapenemase
3. Efflux pump

Drug options = aztreonam, colistin, ticarcillin-clavulinic acid

Question 393

c. diph culture, and findings

Answer 393

Grows within the zone of a fosfomycin disk on blood agar
Selective media = Cystine tellurite blood agar or Tinsdale Agar base medium
CTBA grows gun metal grey
TIN grows with a brown/black halo around the colony
Catalse positive
Nitrate reduction negative, Motility negative, Urea negative, Reverse CAMP negative
Non lipophilic
Neisser or Loeffler’s blue stain – chromatic granules
Confirm toxin production or not – Elek test or modified Elek test – to look for precipitate of toxin with antitoxin. Screen with PCR first and then do Elek test on the ones that are positive.

Question 394

5 controls used in PCR

Answer 394

Internal control
Positive control
Negative control
Blank control
Patient known positive

Question 395

1. List 6 quality indicators for blood cultures.

Answer 395

1) Contamination rates
2) Positivity rates
3) Bottles adequately filled with blood
4) Number of bottles collected
5) Transit time from collection to incubation
6) Reporting time for gram stains of positive cultures
7) Time to positivity
8) Amended reports issued
9) Physician satisfacation
10) Specimen labeling

Question 396

2. Name 4 preanalytical quality indications used for monitoring the handling and transport of specimens coming from the Far North.

Answer 396

1) Shipping temperatures
2) Time from collection to arrival in laboratory
3) Specimens damaged in transit
4) Specimens unlabeled or mislabeled
5) Specimen requisitions
6) Proper transport media

Question 397

3. List 3 postanalytical quality indicators.

Answer 397

1) Time to reporting of results
2) Accuracy of reports issued
3) Client satisfaction audits
4) Reporting of critical results

Question 398

4. Pt. with painless mass at angle of jaw. (classic actinomycosis picture)
   a. What would you look for in the pus, macroscopically
   b. What would you find on hematoxylin-eosin staining?
   c. What is the antimicrobial of choice?
   d. What other bacteria is often found (more) in these infections?

Answer 398

a. Sulfur granules
b. Splendor-Hoeppeli phenomena (filaments radiating away from the bacteria with intensely eosinophilic material, asteroid like)
c. Pencillin
d. Eikenella, Fusobacterium, Capnocytophaga, Staphylococcus, Streptococcus
Others that could cause this: Nocardia, Actinomadura, Streptomyces madurae

Question 399

5. Pt. bitten by a cat and develops rapidly progressive cellulitis. Organism grows as GNB, scant on BAP & choc, no growth on MacConkey.
   a. What is the most likely etiologic agent?

Answer 399

Pasteurella multocida

Question 400

b. List 4 phenotypic tests and the expected results for Pastuerella multocida

Answer 400

Oxidase = Positive
Catalase = Positive
Urease = Negative
Ornithine Decarboxylase = Positive
Indole = Positive
Acid from maltose
Nitrate = positive

Question 401

6. Regarding the detection of HPV DNA in women >30 years of age:
   a. What are 2 techniques to detect HPV DNA?

Answer 401

Hybrid Capture Assay
Amplicor HPV Test (PCR)
TMA

Question 402

b.List 2 advantages o HPV DNA tests, complementary to cervical cytology (>30y).

Answer 402

Increase specificity for diagnosing high grade lesions

Decrease amount of individuals requiring colposcopy

Question 403

c.List 6 genotypes that must be detected in HPV

Answer 403

16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59

Question 404

d.Why are HPV DNA tests not indicated in women <30y of age?

Answer 404

May detect incident infection that may spontaneously clear in 6-18 months.
Leads to unnecessary colposcopy

Question 405

Tenover criteria

Answer 405

Identical: 0 genetic events, 0 different bands
closely related: 1 genetic event, 2-3 different bands
possibly related: 2 genetic events, 4-6 different bands
unrelated: >=3 genetic events, >=7 different bands

Question 406

S. aureus
Micrococcus sp
Rothia mucilaginosa

Strict aerobe?
6.5% NaCl?
Bacitracin?

Answer 406

S.aureus = Not strict, Grows in salt, R to bacitracin
Micrococcus = Strict aerobe, Grows in salt, S to bacitracin
Rothia = Not strict, No growth in salt, S to bacitractin

Question 407

Hair perforation and Urease for

T. rubrum
T. mentagrophytes

Answer 407

T. rubrum - Hair perf neg, Urease neg

T. mentagrophytes - Hair perf pos, Urease pos

Question 408

10. List 2 different mechanisms of resistance to aminoglycosides.

Answer 408

1) Decreased uptake (changes in outer membrane permeability, decreased inner membrane transport, or active efflux)
2) Aminoglycoside Modifiying Enzymes (phosphotransferase, modify the drug)
3) Modification of the target site by mutation in ribosomal proteins or 16S RNA or posttranscriptional methylation of 16S RNA

Question 409

a. Is there a difference in the criteria between S. aureus & S. lugdunensis?

Answer 409

No

Question 410

b. Describe hVISA and explain what the term means.

Answer 410

Heterogeneous Vancomycin Intermediate Staphylococcus aureus. A subpopulation of S. aureus that have increased MIC to vancomycin (in the intermediate range).

Question 411

12. What are the breakpoints and mechanisms involved in:

a. VISA?

Answer 411

MIC 4-8
Mechanism = Increase in cell wall thickness by accumulation of peptidoglycan precursors which prevent diffusion of the drug into the organism.

Question 412

What are the breakpoints and mechanisms involved in:

a. VRSA?

Answer 412

MIC >=16
Mechanism = vanA gene conferring vancomycin resistance by altering peptidoglycan cross-linking targets. (D-Ala-D-Ala to D-Ala-D-Lac, or D-Ala-D-Ser)

Question 413

13. For each enzyme, name an indicator that can be used in the laboratory to detect their presence. Indicate ‘none’ where appropriate.
    a. β-metallobetalactamase
    b. ESBL
    c. AmpC
    d. TEM-1

Answer 413

a. β-metallobetalactamase - Inhibition assay using meropenem with and without dipicilonic acid, increase in zone diameter with the addition of dipicolinic acid or EDTA
b. ESBL – Disk inhibition assay using cefotaxime and ceftazidime with and without clavulinic acid with a >=5 mm diameter with addition of clavulinic acid. (MAST test)
c. AmpC – MAST test, but with no change in zone diameter and resistance to Cefoxitin. Or cloxacillin
d. TEM-1 – None (or what about the nitrocefin test

Question 414

14. IVDU with acute nodular lymphangitic lesions. Culture positive for GNB growing in 48h on choc, oxidase negative, weak catalase positive, and urea negative.
    a. What is the most likely etiologic agent?

Answer 414

Francisella tularensis

Question 415

b. What are the nutritional needs of Fransicella tularensis?

Answer 415

Cysteine
Thiosulfate

?Iron

Question 416

15. What are 5 microbiological or epidemiological features of an event that lead to the suspicion of bioterrorism or a biocrime?

Answer 416

i. Multiple patients presenting with a similar illness
ii. Patient presenting with an illness consistent with a diagnosis
of an agent of possible bioterrorism
iii. Cultivation of an organism with an unusual drug resistance
iv. Atypical disease presentations
v. Shorter incubation time that usual
vi. Following a specific threat
vii. Recurrence of a rare disease
viii. Disease during an unusual season

Question 417

16. In the CCR5 testing for maraviroc, you are told that there was “inability to amplify”. List two virologic causes to explain this phenomenon.

Answer 417

1) Viral load below the limit of detection for the assay

2) Inhibitors present

Question 418

17. List 5 steps of the Gram stain

Answer 418

1) Fix smear with heat or methanol
2) Flood slide with crystal violet for 30 sec, rinse with water
3) Flood slide with Iodine, let sit for 30 sec, rinse with water
4) Decolorize with Acetone-Alcohol until run off is clear, rinse with water
5) Counterstain with Safranin for 30 sec - 1 minute, rinse with water

Question 419

What are 2 bacteria that tend to overdecolourize?

Answer 419

1) Clostridium clostridiforme

2) Streptococcus pneumoniae

Question 420

18. What are 4 phenotypic criteria common to Enterobacteriaceae

Answer 420

1) Ferment glucose
2) Gram stain negative
3) Catalase positive
4) Faculative anaerobes
5) Non-sporing
6) Reduce nitrate to nitrite (there are some exceptions)

Question 421

19. What are 3 bacterial genera that do not stain with the Gram stain?

Answer 421

1) Coxiella
2) Mycoplasma
3) Chlamydia
4) Treponema
5) Ureaplasma

Question 422

20. List 4 members of the Mycobacterium tuberculosis complex.

Answer 422

1) Mycobacterium tuberculosis
2) Mycobacterium africanum
3) Mycobacterium bovis
4) Mycobacterium caprae
5) Mycobacterium microti
6) Mycobacterium canettii
7) Mycobacterium pinnipedii

Question 423

21. What are 3 NTM’s that can give a false positive on an IGRA?

Answer 423

1) Mycobacterium marinum
2) Mycobacterium kansasii
3) Mycobacterium szulgai (Can cause adult pulmonary disease)
4) Mycobacterium flavescens (Rapid grower)

Question 424

22. Regarding sputum culture for mycobacteria:

a. What are two agents for decontamination?

Answer 424

1) NALC-NaOH (N-acetyl –L-cysteine Sodium Hydroxide)* most common
2) Oxalic acid
3) HCl
4) Benzalkonium chloride-triodium phosphate
5) Cetylpyridnium chloride

Question 425

b. What are the minimum and maximum expected rates of contamination for sputum cultures for mycobacteria?
c. If the rate is lower than the minimum, what is the main cause?

Answer 425

Minimum = 2%
Maximum = 5%

Too many mycobacteria are lost in the decontamination process

Question 426

23. A GNB is growing on the MacConkey, H2S+. Salmonella is suspected.
    a. Name 2 other H2S+ bacteria.

Answer 426

1) Citrobacter freundii
2) Proteus vulgaris
3) Edwardsiella tarda
4) Proteus mirabilis
5) Morganella
6) Erysipilothrix rhusiopathie

Question 427

24. What is the principal mechanism of resistance of Salmonella to the fluoroquinolones?

Answer 427

gyrA gene – altered target for quinolone binding to active site (QRDR of topioisomerase enzyme)

Question 428

25. What are 2 antigens used in rapid diagnostic tests for malaria?

Answer 428

1) Hrp2 (Histine rich protein 2) – P. falciparum
2) Aldolase – All species of Plasmodium
3) Plasmodium Lactate Dehyrodgenase (pLDH) – Antibodies specific to both P. falciparium and all Plasmodium species

Question 429

In comparing level 3 laboratories against level 2:

a.List 3 operational or administrative characteristics of a level 3 laboratory

Answer 429

1) Restricted access with controlled access system (record of all persons entering and exiting)
2) Full coverage dedicated protective clothing to be worn
3) Routine cleaning to be done by specifically trained staff
4) All specimens to be opened in a BSCII cabinet
5) All material decontaminated prior to removal

Question 430

b.List 3 layout and design characteristics of a level 3 laboratory

Answer 430

1) Exhaust air Hepa filtered
2) Anteroom with a walk through shower
3) Negative pressure airflow
4) Windows to be nonopening and sealed
5) Mechanism in place so both doors can not be opened at the same time

Question 431

27. Child returns from Mexico; drank lots of raw goat milk. Now has fever & night sweats.
    a. What is the most likely diagnosis?

Answer 431

Brucella

Question 432

b. Name 3 species of Brucella that are pathogenic in humans

Answer 432

Brucella suis (swine)
Brucella melitensis (goats/sheep)
Brucella abortus (cattle)
Brucella canis (canines)

Question 433

28. 16 y.o. patient has 2 weeks of sore throat, fever, and lymphadenopathy.
    a. What is the most likely diagnosis?
    b. What are 2 other possible diagnoses?

Answer 433

a. EBV

b.
CMV
Acute HIV
Neisseria gonorrhea

Question 434

Virus family of Bocavirus?

Answer 434

Parvoviridae

Question 435

Virus family of hMPV?

Answer 435

Paramyxoviridae

Question 436

30. List 4 types of nucleic acid amplification tests.

Answer 436

1) Polymerase Chain Reaction (PCR)
2) Strand displacement assay (SDA)
3) Transcription Mediated Amplification (TMA)
4) Ligase Amplification Reaction (LAR)
5) Nucleic Acid Sequence Based Amplification (NASBA)
6) LAMP

Question 437

31. Name two classes of carbapenemases (Ambler classification) and for each, name an organism that can produce this enzyme.

Answer 437

Class D = Oxa-48 = E. coli, Acinetobacter
Class A = KPC = Klebsiella pneumoniae
Class B = IMP = K. pneumoniae, Pseudomonas, Acinetobacter

Question 438

32. 63 y.o. female, with BAL likely + for Nocardia.

a. Name 2 other GPB that are modified acid-fast +.

Answer 438

1) Rhodococcus equi
2) Gordonia
3) Mycobacterium
4) Tsukamurella

Question 439

32. 63 y.o. female, with BAL likely + for Nocardia.

b. List 4 antibiotics that would be on the primary antibiogram.

Answer 439

1) TMP-SMX
2) Imipenem
3) Ceftriaxone
4) Amoxicillin-Clavulinic Acid
Also criteria for: Amikacin, Cipro, Clarithromycin, Linezolid, Minocycline, Moxifloxacin, Tobramycin
Secondary = Cefepime, Cefotaxime, Doxycycline

Question 440

33. Regarding Giardia lamblia:

a. List 2 advantages of EIA’s

Answer 440

1) Rapid
2) Minimal technical training required
3) More sensitive than O&P

Question 441

33. Regarding Giardia lamblia:

b. List 2 disadvantages of EIA’s.

Answer 441

1) Does not allow for dection of other potential pathogens
2) Can only be used on stool samples
3) Only detects the cysts

Question 442

c. Name 2 other specimens aside from stool where Giardia can be found.

Answer 442

1) Duodenal aspirates

2) Duodenal biopsy

Question 443

34. Name 2 mechanisms of resistance of S. pyogenes to macrolides and for each, describe the antimicrobial susceptibility phenotype.

Answer 443

1) mef gene – Codes for an efflux pump: Erythromycin R, Clindamycin S
2) erm gene – Ribosomal methylation: Erythromycin R, Clindamycin R. Higher Erythro MIC

Question 444

35. 83 y.o. female, with meningitis. GPB in CSF.

a. What is the most likely organism?

Answer 444

Listeria monocytogenes

Question 445

b. List 6 tests for Listeria, and the expected results

Answer 445

1) Catalase – positive
2) Bile esculin – positive
3) Room Temperature Tumbling motility – positive
4) CAMP – Positive
5) VP – positive
6) Methyl Red – Positive
7) Beta hemolytic
8) Hippurate – Positive
9) H2S from Glucose – Negative

Question 446

36. CAPD pt. with PD infection. Culture shows GPC, cat -, LAP -, PYR -, and vanco R.
    a. What is the most likely organism?

Answer 446

Leuconostoc

Question 447

b. List 3 other GPC with intrinsic resistance to vancomycin.

Answer 447

1) Pediococcus (LAP+, PYR-, tetrads or clusters)
2) Weissella
3) Enterococcus gallinarum
4) Enterococcus casseliflavus

Question 448

37. Coxiella serology - phase I IgG 1:1600, phase II IgG 1:50. Interpret.

Answer 448

Chronic infection

Phase I >800, and Phase II is <200

Question 449

38. Your laboratory performs a specialized test for which there is no external control. List 2 ways to ensure the results produced are reliable.

Answer 449

1) Use a patients previous positive sample as a control in your test
2) Back it up with another method of testing

Question 450

39. For Neisseria gonorrhoeae:

a. Name 2 commercially available selective agar for isolation of this organism.

Answer 450

1) Thayer Martin Agar

2) Martin Lewis Agar

Question 451

b.Name 2 rapid tests for presumptive ID when Neisseria gonorrhoea grows on selective agar.

Answer 451

1) Oxidase positive

2) Gram stain to show gram negative diplococci

Question 452

c.List 4 methods of confirmation Neisseria gonorrhoea

Answer 452

1) Hybridization probes
2) DFA
3) Utilizes glucose, not maltose or lactose or sucrose
4) Chromogenic Enzyme Substrate Tests
5) DNA Sequencing
6) MALDI-TOF

Question 453

40. What is the value of an EIA serology for B. burgdorferi in a pt. with erythema migrans?

Answer 453

Clinical diagnosis, even if EIA was negative could be too early and you should treat anyways.

Question 454

41. Regarding arboviruses:

a. List 4 tests to confirm a suspected infection of WNV:

Answer 454

1) CSF IgM
2) Serum IgG and IgM
3) Blood PCR
4) Plaque Reduction Neutralization Assay

Question 455

b.What are 3 arboviruses present in Canada?

Answer 455

1) Eastern Equine Encephalitis
2) St. Louis Encephalitis
3) Powassan virus
4) Western Equine Encephalitis
5) WNV

Question 456

List three tests/characteristics that differentiate B. anthracis and B. cereus, and give the expected results for each.

Answer 456

Hemolysis
Motility
Penicillin Susceptibility

Question 457

b.Name one test to confirm the ID of Bacillus anthracis

Answer 457

Real time PCR for toxin genes (pXO1, pXO2 and a Bacillus chromosomal target)

Others:

• Demonstration of lysis by y-phage
• Fluorescent Ab detection of the capsule

Question 458

c.Name 2 virulence factors of B. anthracis.

Answer 458

1) Capule (antiphagocytic, encoded by pXO2)
2) Exotoxins (encoded by pXO1) =
a. Edema toxin (Edema factor + Protective antigen)
b. Lethal toxin (Lethal factor + Protective antigen)

Question 459

43. Name 2 ways to confirm suspicion of a white mould of being Coccidioides.

Answer 459

1) Specific DNA probe
2) Immunodiffusion test for exoantigen
3) Cultivation for spherules in special synthetic Converse medium
4) Animal inoculation for in vivo production of spherules

Question 460

44. Regarding influenza resistance to oseltamivir:

a. What gene would be targeted if a genotypic resistance test was created?

Answer 460

Neuraminidase gene (NA gene)

Question 461

What is the most frequent mutation of influenza A that causes oseltamivir-R?

Answer 461

H274Y

Influenza Resistance Mutations to NAIs:
Flu A/H3N2 E119V, R292K
Flu A/H1N1 H274Y
Flu B R152K

The H1N1 H274Y resistance mutation is the reason why most H1N1 are resistant to Oseltamivir, but they are still susceptible to Zanamivir. With the pandemic flu (pH1N1) those were now sensitive to Oseltamivir again.

Question 462

45. A technologist breaks a tube containing M. tuberculosis.
    a. What are 5 chronological steps that should follow?

Answer 462

1) All personnel to clear the area
2) Hold breath if not in PPE
3) Exit for at least 1 hour
4) Warning signs alerting others
5) Wear proper PPE before going in
6) Clean up spill safely
7) Post exposure follow up of personnel

Question 463

46. List 4 microscopic methods to confirm the presence of P. jiroveci in a BAL:

Answer 463

1) DFA (C&T)
2) Methenamine Silver Stain (C only)
3) Giemsa (C&T)
4) Calcoflour White (C only)
5) Papanicolaou (C only)
6) Toludine Blue O (C +/-T)
7) DiffQuik

Question 464

47. Regarding molecular typing methods in bacteria:

a. List 4 important characteristics for a good molecular typing test.

Answer 464

1) Typability - % of typable isolates among the total number of isolates subtyped (data to lead to the designation of subtypes)
2) Reproducibility
3) Discrimatory Power
4) Convenience Parameters (Rapidity, cost, technical demands, accessiblility, ease of data management)

Question 465

b. Name 3 common techniques for typing of S. aureus:

Answer 465

1) PFGE (SmaI)
2) MLST – Sequence based
3) Single-Locus Sequence Typing (spaA for S. aureus) – Sequence based
4) Multiple-Locus Variable-Number Tandem-Repeat analysis (MLVA) – Sequence based
5) Ribotyping (RFLP)
6) Repetative Sequence-Based PCR

Question 466

48. List 4 reasons as to why a confirmed strain of S. aureus could give a negative test for free coagulase, after the tube was incubated at 35°C for 4 hours:

Answer 466

1) Too short of an incubation time, re read after 18 hours
2) False negative due to production of staphylokinase (lyses the clot)
3) Plasma used was not sterile
4) Colony tested was not pure
5) Low inoculum
6) Presence of fibrinolysin that can dissolve the clot (activity increased at 37 degrees, that’s why it is kept at room temp after 4 hours)

Question 467

49. List 2 characteristics of superantigens that explain their high pathogenicity, and list 2 organisms that produce them.

Answer 467

Charasteristics:

1) Activate a large number of T-cells (20%) independent of processing and presentation by an antigen presenting cell
2) Does not require a co-receptor

Organisms:

1) Staphylococcus aureus
2) Streptococcus pyogenes

Question 468

50. Name 2 aerotolerant Clostridium species, and name a rapid test that differentiates Clostridium from Bacillus.

Answer 468

1) Clostridium tertium
2) Clostriudium histolyticum
3) Clostridium carnis
4) Clostridium septicum (Pubmed…)

Rapid test = Catalase (Clostridium Neg, Bacillus Pos)
Also, Clostridium sporulate only anaerobically.
Most Clostridium are catalase negative (can’t find which are catalase positive)

Question 469

51. Pt. with breast ca., chemo, and secondary neutropenia. Becomes febrile; broad-spectrum antibiotics administered through central catheter. Still febrile on day 4; blood cultures + for yeast (non-filamentous).
    a. List 2 antifungals appropriate for empiric therapy in this infection, and for each, explain the mechanism of action.

Answer 469

1) Amphotericin B – Binds to egosterol and alters cell membrane permeability causing cell contents to leak out
2) Caspofungin – Inhibits 1-3-B-D-glucan synthase, disrupting cell wall synthesis

Question 470

b. List 2 steps (aside from antifungals) important in this patient with fungemia management

Answer 470

1) Remove the central catheter

2) Repeat blood cultures until negative

Question 471

52. List 4 types of E. coli and explain the mechanism by which they cause diarrhea.

Answer 471

1) ETEC: Enterotoxogenic E. coli
2) EHEC: Enterohemorrhagic E. coli
3) EPEC: Enteropathogenic E. coli
4) EAEC: Enteroaggregative E. coli
5) EIEC: Enteroinvasive E. coli

ETEC Heat stable and heat liable enterotoxins, fimbrial adhesins, secretory diarrhea

EHEC Shiga toxin, intimin-Tir mediated attaching and effacing
EPEC Localized adherence via fundle forming pilus, intimin-Tir mediated attaching and effacing
EAEC Aggregative adherence via several fimbriae, Pet and other toxins, microvillus atrophy
EIEC Cellular invasion, intracellular motility, and cell-to-cell spread

Question 472

1. Young woman, presents with bat bite on neck. Received tetanus vaccine. List 4 steps in her management.

Answer 472

1) Local wound management – cleaning and flushing of wound with soap and water
2) Post exposure prophylaxis with Rabies Ig – into wound
3) Vaccine administration (Day 0, 3, 7, 14. Add day 28 if immunosuppressed)
4) Arrange to have bat tested if available

Question 473

2. Gardener presents with chronic ulcerated lesion on finger and nodules evolving along her forearm.
   a. What is the most likely etiologic agent?

Answer 473

Sporothrix schenckii

Question 474

b. What is the therapy for Sporothrix?

Answer 474

Itraconazole 200 mg po daily

Question 475

c. List 4 other agents of chronic nodular lymphangitis.

Answer 475

1) Nocardia
2) Cutaneous Leishmaniasis
3) Mycobacterium marinum
4) Mycobacterium chelonae
5) Cryptococcus
6) Francisella tularensis

Question 476

3. Fish farmer injured while handling a fish, develops acute cellulitis w/ lymphangitis. Culture grows β-hemolytic, GPC in chains, PYR+, non-grouping by Lancefield.
   a. What is the most likely etiologic agent?

Answer 476

Streptococcus iniae

Question 477

What is the treatment for Streptococcus iniae?

Answer 477

Penicllin G

Question 478

4. What are 3 contraindications to the varicella vaccine?

Answer 478

1) Anaphylaxis to previous varicella vaccine or immediate hypersensitivity or anaphylaxis to any vaccine components
2) Pregnancy
3) Impaired immune function
4) Active infective with tuberculosis

Question 479

5. Regarding the pandemic (2009) H1N1 influenza A strain:

a. Name 6 groups at risk of complications.

Answer 479

1) Pregnant women
2) Elderly patients
3) Children less than 1 year old
4) Diabetic patients
5) Immunosuppressed patients
6) Patients with chronic lung diseases
7) Cardiac disease

Question 480

b. What is the adjuvant in the pandemic flu vaccine, and its composition?

Answer 480

MF59 – Oil in water adjuvant

Question 481

6. What are 2 clinical syndromes associated with HHV-6?

Answer 481

1) Roseola Infantum
2) Infectious mononucleosis
3) Infant Febrile Seizures
4) Meningoencephalitis (rare)

Question 482

7. What are 6 pathogens requiring airborne isolation precautions?

Answer 482

1) Tuberculosis
2) SARS
3) Measles
4) Varicella
5) MERS CoV
6) Smallpox
7) Monkeypox

Question 483

8. A pregnant nurse presents with concerns about CMV infection
   a. Describe 4 common clinical findings at birth in congenital CMV.

Answer 483

1) Retinitis
2) Microcephaly
3) Intracerebral calcifications
4) Jaundice
5) HSM
6) Purpura

Question 484

b. What is the main risk factor for development of congenital CMV?

Answer 484

Primary infection during pregnancy

Question 485

c. What is the diagnostic test to do in the first 2-4 weeks of life to confirm congenital CMV?

Answer 485

Detection of CMV in the urine or saliva (PCR or culture)

Question 486

9. 70 y.o. female presents with chronic cough, hemoptysis, and RUL infiltrate. AFB smear +, DNA probe + for M. TB complex. She takes care of her 2 & 4 y.o. grandchildren. The 4 y.o. has mediastinal lymphadenopathy; the 2 y.o. has a negative PPD.
   a. What treatment would you start for the index patient?
   b. What are 2 other presentations common in the pediatric population?
   How do you manage each child?

Answer 486

Treatment for index person:
	Rifampin
	Isoniazid
	Pyrazinamide
	Ethambutol

Pediatric presentations = Fever, Growth delay, Weight loss
Management:
4 year old – Can diagnose with a positive TST or IGRA, abnormal chest Xray or physical exam and epi link. Gastric aspirate and then treat
2 year old – Treat for active or latent depending on CXR, history, physical and gastric aspirate

Question 487

10. List 2 effective therapies against lice

Answer 487

1) Permethrin Hair Rinse
2) Pyrethrin Shampoo
3) Lindane Shampoo (poisonous – not for children <2)
4) Topical Ivermectin

Question 488

11. 50 y.o. male with decompensating right-sided CHF, with no valve disease on echo. Previously lived extensively in S. America for many years.
    a. What is the most likely etiologic agent?

Answer 488

Trypanosoma cruzi

Question 489

Trypanosoma cruzi:

b. How is this organism acquired normally?
c. What is the most accessible test?
d. What is the most useful test?

Answer 489

b. How is this organism acquired normally?
Bite of a triatome bug (Rhodnis prolixus)
c. What is the most accessible test?
Blood films
d. What is the most useful test?
PCR

Question 490

e. Name an effective therapy for T. cruzi?

Answer 490

Acute = Nifurtimox or Benznidazole
Chronic = Support therapy

Question 491

12. 18 y.o. male presents with fever, headache, skin lesions (not in shock). Aspiration of a hemorrhagic bulla shows GNDC. Blood & CSF cultures obtained.
    a. What are the 2 most likely etiologic agents?

Answer 491

Neisseria meningititis

Neisseria gonorrhea

Question 492

b. What are 3 elements of management that need to be dealt with immediately for N. meningitis?

Answer 492

Start IV antibiotics with Ceftriaxone
Place patient on Contact and Droplet precautions
Notify treating physician
Notifly infection control

Question 493

13. 20 y.o. male with multiple sexual partners, now with septic arthritis of the knee. What are the 3 most likely pathogens in this context?

Answer 493

1) Neisseria gonorrhea
2) Staphylococcus
3) Streptococcus

Question 494

14. Female hospitalized with PID. Anaphylactic allergy to pen. Cipro resistance 7% in area.
    a. What treatment would you begin?

Answer 494

Clindamycin 900 mg IV q8h PLUS
Gentamicin 1.5 mg/kg IV q8h (first give a loading dose of 2 mg/kg IV)
+/- Doxycylcine (if you think it’s CT or GC)

Question 495

b. What oral treatment would you step down to given allergy to pen for PID?

Answer 495

Clindamycin 450 mg po QID for a total of 14 days OR

Doxycycline 100 mg po BID

Question 496

What are 2 types of meat that can transmit trichinellosis?

Answer 496

1) Pork
2) Bear meat
3) Wild boar
4) Walrus

Question 497

16. 28 y.o. female travelling to Nepal. Diarrhea with 10 BM’s/d, with malaise & myalgias. Stool cultures negative, Crypto EIA negative. Circular, modified Kinyoun + organism, measuring 10 μm.

a. What is it?
b. What is the treatment?

Answer 497

Cyclospora cayetanensis (used to be called Cryptosporidium grande)

TMP-SMX 1 ds tab BID x 7 days

Question 498

17. Pt. recently dx’d. with HIV, CD4 50. Appears dehydrated. Investigations show Crypto. What are 3 steps to proceed with in his care? Cryptococcal meningitis:

Answer 498

1) Initiate Amphotericin B + Flucytosine
2) LP to determine pressure and repeat LPs to control increased ICP as needed
3) Initiate HAART therapy 2-10 weeks after starting treatment for crypto meningitis
4) Stabilize patient from dehydration
5) Repeat LP at 2 weeks for sterility

Question 499

18. Woman returning from Indonesia. Fever, cough, and chest pain, with diffuse infiltrates on CXR. Eosinophilia. What are 4 parasitic causes to explain her symptoms?

Answer 499

1) Strongyloides stercoralis
2) Hookworm
3) Ascaris lumbricoides
4) Paragonimus westermani
5) Wucheria bancrofti
6) Brugia species

Question 500

19. Woman returning from Philippines, visiting friends/relatives, no malaria proph. Presents with fever, hypotension, acute renal failure (creat 230). Blood smears show intraerythrocytic parasite, parasitemia 2.9%, with multiple equatorial band forms. (photo of schizont of roughly 10 nuclei & band forms)
    a. What is the disease?
    b. What is the treatment?

Answer 500

P. knowlesi

Chloroquine phosphate (600 mg base po x 1 immediately, then 300 mg base at 6, 24, and 48 hours)

Question 501

20. Pt. w/ HIV, CD4 50, presents with seizures. Imaging reveals hypodense brain lesions, with uptake of contrast and perilesional edema.
    a. What are the two most likely diagnoses?
    b. What treatment should be started?

Answer 501

Toxoplasmosis
Primary CNS lymphoma

b. What treatment should be started?
Sulfadiazine + Pyrimethamine
Use above for 6 weeks then half the dose of each for maintenance therapy until CD4 is >200 with HAART

Question 502

21. Pt. on steroids, presents with headache & fever. LP shows high WBC (7000) with lymphocytic predominance. Round encapsulated yeasts seen.
    a. Cryptococcal latex antigen is negative. Why?

Answer 502

False negative due to prozone effect

Low antigen concentration

Question 503

22. Pt. from Congo, newly dx’d. with HIV, CD4 10. ARV’s started 6 weeks ago. Abdo pain has since developed, and imaging shows multiple enlarge intraabdominal lymph nodes.
    a. What is the name of this clinical picture?

b. What are the 2 most likely pathogens?
c. What test should be done?
d. What treatment should be started?

Answer 503

a. What is the name of this clinical picture?
Immune Reconstitution Inflammatory Syndrome (IRIS)
b. What are the 2 most likely pathogens?
Tuberculosis
MAC

c. What test should be done?
Biopsy with pathology, fungal, routine, mycobacterial culture

d. What treatment should be started?
Anti TB treatment?

Question 504

24. 69 y.o. female with total hip replacement 2y ago. Now has hip pain. Joint aspiration + for S. aureus - R to pen, S to all other antibiotics. What antibiotic(s) would you recommend and for how long?

Answer 504

Cefazolin IV or Cloxacillin IV or Ceftriaxone x 6 weeks
+ Rifampin PO x 6 weeks if debride and retention or 1stage exchange
(If 2 stage exchange or permanent ressection then no rifampin)
Then oral therapy with Cipro or Levo + Rifampin for 3 months with a hip, or 6 months with a knee in all patients who have had debridement and retention or 1-stage exchange

Consider chronic suppression in Debride and retention or 1 stage exchange indefinitely with Keflex, Clox, Septra or Minocycline

Question 505

25. Female with infection of external ear after piercing. No response to cefazolin. What are the 2 most likely pathogens.

Answer 505

1) Pseudomonas aeruginosa

2) MRSA

Question 506

26. A neonate, a few days old, presents with meningitis, and CSF + for GNB.
    a. What is the most likely organism?

b. Culture + for lactose fermenter on MacConkey, yellow on BAP. Oxidase, DNase, sorbitol negative. What is the most likely organism now?

(Enterobacter cloacae is sorbitol positive, Elizabethkingia is oxidase positive)

c. Baby improves, then worsens after 4-5 d of treatment. 2 possible explanations?

Answer 506

E. coli

b. Culture + for lactose fermenter on MacConkey, yellow on BAP. Oxidase, DNase, sorbitol negative. What is the most likely organism now?

Cronobacter sakazakii

(Enterobacter cloacae is sorbitol positive, Elizabethkingia is oxidase positive)

c. Baby improves, then worsens after 4-5 d of treatment. 2 possible explanations?

Organism has intrinsic AmpC type resistance
Secondary infection with another organism
Abscess

Question 507

27. 6d old neonate with sepsis and marked lymphocytic leukocytosis. Original septic workup is negative, but there is no improvement on antibiotics.
    a. What are 2 non-bacterial pathogens that could explain this picture?
    b. For each one, please discuss tests and specimens for diagnosis.
    c. For each, list measures to prevent further transmission in hospital.

Answer 507

1) HSV
2) CMV

b. For each one, please discuss tests and specimens for diagnosis.
HSV – CSF for PCR
CMV – CSF for PCR or shell vial or culture. Also collect urine and saliva swab for same.

c. For each, list measures to prevent further transmission in hospital.
Contact isolation for HSV if skin lesions
CMV is standard precautions

Question 508

28. 2 mo. old infant with apnea & bradycardia. In the law few days, he has had a runny nose without fever. An aunt came home recently and has been coughing for 3 weeks.
    a. What is the most likely pathogen?

Answer 508

Bordetella pertussis

Question 509

b. What are measures to prevent transmission of B. pertussis, and how long do they need to last?

Answer 509

Droplet isolation until 5 days after effective antibiotic therapy has been initiated or 3 weeks in untreated patient

Chemoprophylaxis for close contacts with Azithromycin x 5 days
(Close contact = household, daycares)

Question 510

29. Patient with MRSA necrotizing pneumonia. It has an MIC of 2 to vancomycin, and is R to erythro, clinda, and TMP-SMX.
    a. List 2 reasons to not give vancomycin alone in this context.

Answer 510

Elevated MIC associated with clinical failure
May represent heteroresitant population of vancomycin intermediate isoaltes, giving vancomycin will select for the resistant population?
Necrotizing pneumonia has a PVL toxin and vanco does not reduce the production of toxins.

Question 511

Patient with MRSA necrotizing pneumonia. It has an MIC of 2 to vancomycin, and is R to erythro, clinda, and TMP-SMX.
b. What are 2 other antibiotics that can be used? (dosing, interval, & duration).

Answer 511

Linezolid 600 mg IV q12h x 14 days
Tigecycline 50 mg IV q12h x 14 days
Telavancin 10 mg/kg IV q24h x 21 days

Question 512

30. Regarding daptomycin:
    a. What is the mechanism of action?
    b. What are the 2 main indications?
    c. What are 2 drugs to be monitored when administered alongside daptomycin?

Answer 512

Binds to the cell membrane and causes rapid depolarization inhibiting DNA, RNA and protein synthesis
b. What are the 2 main indications?
Skin and skin structure infections caused by susceptible isolates
Staphyloccocus aureus bloodstream infections
c. What are 2 drugs to be monitored when administered alongside daptomycin?
HMG-CoA Reductase Inhibitors
1) Atorvastatin
2) Simvastatin
Tobramycin activity is decreased

Question 513

MOA of Tigecycline

Answer 513

Inhibit protein synthesis by binding to the 30S ribosomal subunit

Question 514

MOA of Ertapenem

Answer 514

Inhibit cell wall synthesis by binding to penicillin binding proteins

Question 515

Tigecycline:

3 GNB’s with intrinsically low activity

Answer 515

Morganella
Proteus
Providencia
Pseudomonas aeruginosa

Question 516

Ertapenem:

3 GNB’s with intrinsically low activity

Answer 516

Pseudomonas aeruginosa
Stenotrophomonas
Burkholderia
Acinetobacter

Question 517

32. In the NNIS classification of surgical site infections, what are the 3 components of the score?

Answer 517

1. Type of wound – Contaminated or Dirty
2. Duration of surgery
3. American Anesthesiology score 3,4, or 5 (Patients comorbidities )

Question 518

33. Identify six elements that are part of a structured antimicrobial stewardship program.

Answer 518

1) Prospective audit with intervention and feedback
2) Formulary restriction and preauthorization requirements for specific agents
3) Education
4) Guidelines and Clinical Pathways
5) Antimicrobial order forms
6) Dose optimization
7) Conversion from parentral to oral formulations
8) De-escalation of therapy

Question 519

34. List 6 factors influencing the transmission of TB from person to person

Answer 519

1) Site of infection (Laryngeal more contagious)
2) Smear positivity
3) Proximity of contacts
4) Duration of exposure
5) Cough
6) Crowding and room ventilation
7) Treatment
8) Cavitary disease

Question 520

35. Elderly male present with 2 months of subacute fever, now has a new murmur. Blood cultures + for GPC in chains.
    a. What therapy is appropriate? (dose, interval, duration)

Answer 520

Vancomycin 15-20mg/kg/dose q12h x 6 weeks

+/- Gentamycin 1 mg/kg q8h x 6 weeks

Question 521

b. What are 4 indications for surgery in infective endocarditis?

Answer 521

Large Abscess despite appropriate antibiotic thearpy
Heart failure unresponsive to medical management
>=1 embolic event during first 2 weeks of antibiotics
Anterior Mitral leaflet vegetation >1 cm
Persistent vegetation after systemic embolization
Increase in vegetation size despite antibiotics
Valve perforation or rupture
New heart block
Fungal IE

Question 522

List 4 clinical syndromes caused by Coxiella burnettii.

Answer 522

1) Self limited Febrile Illness
2) Endocarditis
3) Post Q fever Fatigue Syndrome
4) Pneumonia
5) Hepatitis
6) Osteomyelitis
7) Q fever in infancy
8) Q fever in the immunocompromised host
9) Q fever in pregnancy

Question 523

37. Regarding foodborne infections:

a. List 4 pathogens commonly associated with unpasteurized dairy products.

Answer 523

1) Brucella abortus
2) Yersinia entercolitica
3) Coxiella burnetii
4) Cryptosporidium parvum (cows)
5) Listeria

Question 524

b. List 4 pathogens commonly associated with contaminated fruits & vegetables.

Answer 524

1) Shiga toxin producing E.coli (STEC)
2) Shigella
3) Norovirus
4) Cyclospora cayetanensis (Raspberries)
5) Salmonella
6) Bacillus cereus

Question 525

38. Male patient with colon ca., presents with fever and buttock pain. CT shows gas bubbles in the paraspinal and gluteal muscles. Blood culture + with long GPB.
    a. What is the infection?

b. What is the etiologic agent? (include species)

Answer 525

Clostridial necrosis

Clostridium septicum

Question 526

39. What are 4 indications for GBS prophylaxis in the intrapartum period?

Answer 526

1) GBS bacturia during the pregnancy
2) Previous infant with GBC infection
3) Positive GBS screen after 36 weeks
4) No GBS screening swab collected prior to labour onset

Question 527

a.What is the best alternative for GBS prophylaxis if the patient has a non-type I allergy to penicillin?

Answer 527

Cefazolin

Question 528

40. CMV infection (not disease) post-BMT. Ganciclovir started, followed by valganciclovir, while also on cyclosporine and prednisone. During therapy, pulmonary infiltrates develop, and CMV viremia increased by 3 log. CMV culture from BAL is +.
    a. What is the cause of deterioration in the patient?
    b. What would be the most useful test in the management of the patient?

c. What are 2 steps in the management of this patient that should be undertaken?

Answer 528

CMV pneumonitis

b. What would be the most useful test in the management of the patient?
Resistance testing of CMV isolate
c. What are 2 steps in the management of this patient that should be undertaken?
Decrease immunosuppression
Change therapy to Cidofovir or Foscarnet
If UL97 mutant (activation one) then Cidofovir will work
If the mutation is UL54 (polymerase) then there may be cross resistance to Cidofovir too

Question 529

41. Hemorrhagic cystitis post-BMT, with negative bacterial culture of urine. What are 3 most likely organisms involved?

Answer 529

1) BK virus
2) Adenovirus
3) JC Virus
4) HSV
5) CMV
6) HHV6

Question 530

42. Regarding Burkholderia cepacia in CF patients:

a. What are the two most common genomovars?

Answer 530

II and III (multivorans and cenocepacia)

Question 531

b. What are 2 clinical features of B. cepacia syndrome?

Answer 531

1) Necrotizing pneumonia

2) Hematogenous dissemination

Question 532

43. Taiwanese patient presents with 5 cm liver abscess. Abscess drainage grows a mucoid lactose fermenter on MacConkey. VP, indole, and lysine +.
    a. What is the most likely organism?
    b. What are 2 other metastatic foci in patients that have this picture?

Answer 532

Klebsiella oxytoca

1) Meningitis
2) Endophthalmitis

Question 533

44. Patient with orbital cellulitis.
    a. Which form of sinusitis is this commonly associated with?

b. What are 3 physical exam findings associated with this infection?
c. What are 2 complications?
d. What is the treatment?

Answer 533

Acute bacterial rhinosinusitis of the ethmoid sinus

Proptosis, ophalmopelegia, pain with eye movements

Brain abscess, orbital abscess, cavernous sinus thrombophlebitis, vision loss

Vancomycin + Ceftriaxone
Need anaerobic coverage if any intracranial extension. Add metronidazole or do Vanco + PipTazo.

Question 534

45. Patient with HCV & HIV coinfection. Treating with pegylated interferon & ribavirin. What 2 NRTI’s should be avoided if possible, and why?

Answer 534

1) Didanosine
2) Zidovudine
3) Atazanavir

Question 535

46. Patient with rheumatoid arthritis is to receive an anti-TNF inhibitor. PPD +, LTBI treatment started with elevation of hepatic transaminases, and INH is stopped. Her hepatic enzymes resolve. She also takes coumadin for atrial fibrillation.
    a. What is an alternative regimen for her LTBI?

Answer 535

Rifampin for 4 months duration

Question 536

What are 3 side effects of Rifampin?

Answer 536

Discoloration of body fluids (orange)
Hepatotoxicity
Drug interations

Question 537

1. A coryneform bacterium is found in sputum.

a. Name 2 factors that suggest a corynebacterium is significant in the sputum?

Answer 537

1 - Growth is pure

2 - Growth of the coryneform is in heavy amounts and exceeds the growth of respiratory flora

Question 538

b. Which coryneform frequently causes pneumonias?

Answer 538

Corynebacterium pseudodiptheriticum

Question 539

2. In a blood culture, a GPB is found, cat +, beta-hemolytic.
   a. Name 4 biochemical tests to confirm diagnosis.

Answer 539

1 – Bile escuin positive
2 – Room temperature tumbling motility positive
3 – CAMP test positive
4 – VP Positiive
5 – Acid production from glucose
6 – Hippurate hydrolysis positive

Question 540

b. 4 methods of typing of Listeria?

Answer 540

1) PFGE
2) Multilocus variable-number tandem-repeat analysis
3) Multilocus sequence typing
4) Mixed genome DNA microarray
5) Random Amplification of Polymorphic DNA (RAPD)
6) Amplified fragment length polymorphism
7) Ribotyping
8) MALDI-TOF

Question 541

c. Patient has anaphylaxis to penicillin. What do you give for Listeria?

Answer 541

Trimethoprim-Sulfamethoxazole
Alternative: Moxifloxacin (bacteriocidal)

Drug of choice is Ampicilin + Gentamycin for synergy

Question 542

3. Neutropenic patient has a blood culture that is growing anaerobic GPB, cat -, swarming, indole -.
   a. Name the species.

Answer 542

Clostridium septicum

Question 543

b. What two infections are associated with C. septicum?

Answer 543

Myonecrosis

Neutropenic enterocolitis

Question 544

4. Clinical case of echinococcus. Name confirmational serological test.

Answer 544

Complement Fixation
ELISA
Indirect Hemmaglutination

Question 545

5. Woman w/primary HSV infection gives birth.

a. What is the percent risk of transmission to the baby?

Answer 545

40%

SOGC says 30-50%

Question 546

b. Name 6 sites to send specimens from for the baby for congenital HSV?

Answer 546

Blood
CSF
Swab/scrapings of any skin or mucous membrane lesions
Conjuntivae
Nasopharynx
Mouth
Rectum

Question 547

c. List 4 methods of detecting HSV.

Answer 547

Culture
PCR
DFA
EIA

Question 548

d. Treatment of neonatal herpes (dose & duration).

Answer 548

Acylovir: 60 mg/kg/day divided q8h.
14 days if only skin, eyes, mouth
At least 21 days if disseminated or CNS disease followed by 6 months of oral suppressive

Question 549

6. 6 epidemiologic or microbiologic elements that would make you suspect an act of bioterrorism has been committed.

Answer 549

1) Multiple patients presenting with a similar illness
2) Patient presenting with an illness consistent with a diagnosis of an agent of possible bioterrorism
3) Cultivation of an organism with an unusual drug resistance
4) Atypical disease presentations
5) Shorter incubation time that usual
6) Unusual season
7) Unusual demographics

Question 550

7. Treatment of tularemia.

Answer 550

Moderate to severe disease = Streptomyc in 10 mg/kg q12h IM x 10 days or Gentamicin 1.7 mg/kg q8h IV x 10 days
Mild Disease = Ciprofloxacin 500 mg po BID x 14 days or Doxycycline 100 mg po BID x 14 days
Meningitis = Streptomycin or Gentamicin + Chloramphenicol 20 mg/kg IV q6h or Strep/Gent with Doxycycline 100 mg IV BID x 14-21 days

Question 551

8. Name 6 non pathogenic protozoans in stool.

Answer 551

8) Entamoeba hartmanni
9) Entamoeba coli
10) Entamoeba polecki
11) Entamoeba dispar
12) Endolimax nana
13) Iodamoeba butschii
14) Chilomastix mesnili
15) Entamoeba gingivalis
16) Entamoeba moshkovskii
17) Trichomonas hominis

Question 552

9. Name 3 permanent stains used for protozoa in the stool.

Answer 552

Iron hematoxylin
Modified Trichrome Stain
Modified Kinyoun’s Acid Fast Stain

Question 553

10. Name 4 methods for differentiating C. albicans from C. dublinensis. Is it important to differentiate & why?

Answer 553

1) Colonies on CHROMagar - A is light green, D is dark
2) Growth at 42-45 degrees - A grows, D does not
3) Chlamydospores on Cornmeal Agar - A single, D in clusters
4) Colonies on Staib agar - A is smooth, D is rough
5) Assimilation of sugars - A + for Xyl, MDH, The, D neg for all

Question 554

11. Man sustains wound on a boat. Becomes infected w/ GNB that is ox +. Vitek cannot identify; results are Vibrio fluvialis 50%, Aeromonas caviae 50%.
    a. Name 2 special tests to do, and the expected results.

Answer 554

1)	Vibrio static disks (O129)
Vibrio = Susceptible (except V. cholera 0139)
Aeromonas = Resistant
2)	Salt Tolerance
Vibrio = Growth in presence of 6.5% NaCl
Aeromonas = No growth in 6.5% NaCl
3)	Growth on TCBS Agar (Thiosulfate-Citrate-Bile Salts-Sucrose)
Vibro = Growth
Aeromonas = No growth
4)	String Test (with 0.5% sodium deoxycholate)
Vibrio = Positive
Aeromonas = Negative

Question 555

b. Knowing that this is a soft tissue infection related to fresh water, what antibiotic would you give?

Answer 555

Ciprofloxacin 500 mg PO BID?? + Clinda

Up To Date suggests 1st GC + Levo + Doxy? Seems like overkill…

Question 556

12. Name 4 explanations for isolated anti-HBc +.

Answer 556

3) Acute infection, during the window period
4) Previous HBV exposure with waning sAb titres
5) Chronic HBV infection with sAg below the limit of detection
6) False positive anti-HBc

Question 557

13. Klebsiella w/KPC. Name 4 bacteria with this mechanism of resistance. What is a phenotypic confirmatory test?

Answer 557

1) E.Coli
2) Enterobacter cloacae
3) Serratia marcescens
4) Pseudomonas aeruginosa
5) Salmonella
6) Morganella

   Phenotypic confirmatory tests =  Disk inhibition assay with a carbapenem with and without boronic acid

Question 558

14. How to confirm production of metallo-beta-lactamases? Of AmpC?

Answer 558

Metallo-beta-lactamase = Disk inhibition assay with a carbapenem with and without EDTA
AmpC = Disk based inhibitor test using Cefoxitin with or without cloxacillin