Infectious Diseases Flashcards
Which of the following is false about oseltamavir?
A. Reduces duration of symptoms by 1-2 days
B. More effective for Flue B than Flu A
C. Needs dose adjustment in renal impairment and elderly
D. Good for prophylaxis in exposed hospitalized patients
B - opposite, more effective for Flu A than B
Oseltamavir - neuramidase inhibitor
When should oseltamvir be prescribed?
Prophylaxis in exposed hospitalized patients
Symptoms <48hrs in influenza A or B
Which ambler class of antibiotic resistance is new delhi metallo beta lactamases?
How do they transmit resistance?
Class B - metalloBeta lactamses
Plasmid mediated.
Which drugs treat VRE?
Which is not effective against Van A?
Teicoplanin (useleless against Van A, which has a MIC >64)
Tigecycline
Daptomycin
Linezolid
What is the mechanism of action of triazoles?
Inhibits ergosteriol synthesis
Which antifungals are active against aspergillus?
Voriconazole
Caspofungin
Andulafungin
What is the mechanism of action of echinocandins?
Which drugs are in this class?
Caspiofungin, anidulafungin
Inhibits fungal cell wall synthesis
Noncompetitive inhibition of the enzyme 1,3-β glucan synthase –> results in inhibition of B glucan synthesis in the fungal cell wall
Risk factors for TB reactivation
HIV - greatest RF
DM
CKD
Steroids >15mg/1 month
Advanced age
TNF-a inhbitors
Malignant lymphoma
Smoking
Which of the following is a cause of painful gential ulcers?
A. Syphylis
B. Chancroid
C. Granuloma inguinale
D. Lymphogranuloma venereum
B. Chancroid
All others painless
Non-treponemal tests for syphyllis and treponemal tests.
Which is best for screening?
Non-treponemal:
- VRDL
- RPR
- Toluidine Red Unheated Serum Test (TRUST)
Treponemal:
- FT-Abs
- TP-EIA
- TPPA (TP particle agglutination assay)
- chemiluminescense immunoassay (CIA)
- microhemagllutination test for antibodies (MHA-TP)
EIA is best
What are the co-receptors used by HIV for entry into CD4 cells?
CCR5; R5 viruses) or CXC chemokine coreceptor 4 (CXCR4; X4 viruses)
Benefits of TAF over TDF?
Disadvantages?
Less renal toxicity and bone loss
More weight gain
Antibiotic classes with poor CNS penetration?
Aminoglycosides, erythromycin, tetracyclines, clindamycin, and first generation cephalosporins (cephalexin)
Which group of patients should recieve tetanus immunoglobulin when presenting with a traumatic wound?
Patient has received less than 3 doses of tetanus toxoid vaccine or vaccination history is unknown AND a dirty/major wound
All patients should have tetanus vaccine except if less than 5 years since last dose
Antibiotics that inhibit 30s ribosomal subunit
Aminoglycosides
Tetracyclines
Antibiotics that inhibit 50s ribosomal subunit
Macrolides
Linezolid
Lincosamides (lincomycin, clindamycin)
Chloramphenical
Daptomycin mechanism of action
Inhibits bacterial membrane function
Inserts into the membrane of gram positive bacteria–> disrupts membrane –> kills cell
3 major causes of eosinophilic meningitis
3 major parasites:
- Angiostrongylus cantonensis
- Baylisascaris procyonis
- Gnathostoma spinigerum.
Major side effects of abacavir
What class of drug?
Nucleoside reverse transcriptase inhbitoir
Major side effects - highest risk of MI, hypersensitivity reactions in patients with HLAB5701
Which class of HIV drugs cause lactic acidosis?
NRTIs
Which class of HIV drugs cause hyperlipidemia?
Protease inhibitors, -navirs (i.e. lopinavir)
Which drugs can be used to treat aciclovir-resistant HSV?
Which cannot?
Foscarnet or cidofovir
Gancivlovir and valganciclovir also cannot be used as TK mutation inactivates them
What drugs can be used to treat ESCAPM organisms? What ambler class are these organisms?
Carbapenems
Colistin
Amikacin
Fosfomycin for UTIs
Ambler C for cephalosporinases!
Which populations need endocarditis prophylaxis and for which procedures?
Prosthetic cardiac valves (NOT defibs/ppms)
Previous IE
High risk RHD
Cyanotic heart disease with unrepaired shunts/conduits or partially repaired
Procedures involving
- teeth/gums
- infected skin/muscle
- ENT infections (i.e. tonsillectomy, abscess drainage)
GU/GI only if established infection
List the live vaccines
Who are they contraindicated in?
MMR BOYZ japanese diarrhea
MMR, BCG, Oral polio, Yellow fever, VZV, japanese encephalitis, diarrhea - typhoid, rotavirus
Immunocompromise (high dose pred, HIV CD4 <200, transplant, DMARDs)
Pregnancy
Immunodeficiency
Aplastic anemia
Drugs used for MDR TB
bedaquiline, pretomanid, and linezolid
Which of the following is considered a positive mantoux test:
A. Tuberculin skin reaction 8mm from an endemic country
B. 9mm reaction in a prisoner
C. 6mm with abnormal CXR
D. 11mm in a healthy adult
C - correct, ≥5mm and CXR changes/close contact/HIV/immunosupressed = posigtive
A and B - incorrect, needs to be ≥10mm in people at risk of reactivation (i.e. IVDU, malignacy, diabetes, ckd), <4yo, forein country, high risk setting (prisoner, healthcare worker)
D - incorrect, needs to be ≥15mm in healthy individuals >4yo
Which patient groups are at highest risk of developing invasive fungal infections?
Allogenic hematopoetic stem cell transplant
Acute myeloid leukemia
Solid organ transplant (excluding kidney)
Diagnosis of acute Q fever
Isolation of C. Burnetti
Detection of C. Burnetti by NAAT
Seroconversion/4 fold increase in C. Burnetti antibody titre to phase II antigen by complement fixation assay OR indirect immunoflerscence IgG antibody assay (IFA)
Prophylaxis for HIV
CD4 <50 - azithro weekly for MAC + TMP/SMX 3/wk
CD4 <200 - TMP/SMX 3/wk
CD4 <100 + T.Gondii IgG - TMP/SMX daily (full dose)
During a contact trace, it is determined that Mr Jones was exposed to SARS-CoV-2 on Sept
18th (Day 0.) He interacted with Mr Smith on Day 5 before becoming symptomatic on Day 7
and receiving a positive result on Day 9. Mr Smith became symptomatic on Day 8 then was
tested and received a positive result on Day 12.
When assessing the transmission between
Mr Jones and Mr Smith, what is the serial interval?
What is the incubation period for each man?
Serial interval = 1 day
Incubation period = 7 days (MJ), 3 days (Smith)
Serial interval= time between symptom onset of primary case and symptom onset of secondary case (MJ symptomatic D7, Smith D8)
Incubation period is time from infection to symptom onset (D0–>7 MJ, D5–>8 Smith)
A 59 year old male is admitted with febrile neutropaenia.
E. Coli was isolated in blood and urine cultures:
Resistant ampicillin/ceftriaxone
Sensitive ADF/pip-taz/mero/cefepime/gent/TMP-SMX
The best antibiotic treatment is:
A. Meropenem
B. Piperacillin/Tazobactam
C. Piperacillin/Tazobactam plus Gentamicin
D. Amoxicilin/Clavulonic acid plus Vancomycin
A - meropenem
Patient has an ESBL (resistant to ceftriaxone)
MERINO showed mero>pip-taz for ESBL bactermia
When isolated from the blood stream which bacteria has the highest chance of concurrent IE?
a. staph aureus
b. staph mitis
c. staph. gallolyticus
d. e. faecalis
D. S. gallolyticus (bovis)
- among patients with bacteremia due to S. bovis biotype I (S. gallolyticus subsp gallolyticus), IE has been observed in 43 to 100%of cases
s. aures = ~25%
Kaposi sarcoma
- CD4 count
- treatment
- cause
HHV8 (herpes virus)
typically <200 or 150
HAART alone in most
Treatment of strongyloides?
Risk factors?
RF = malignancy, HTLV1, AIDs, immunosupression, alcohol, malignancy
Treat with ivermectin
Bacteria associated with rhomboencephalitis
Lysteria - inflammation of the brainstem with ataxia, nystagmus and CN palsies
Bacteria that produce a lactamase penicillinase
Mechanism of staphs (mSSA), escapms (enterobacteracia) and ESBLs Klbeseall
Bacteria with altered D-ala-D-ala in cell wall
Mechanism of VRE (Van genes)
Bacteria that Altered penicillin-binding protein (PBP2) in cell wall
MRSA, PBP→ PBP2, recnoded by an acquired medA gene on staph cassette mobile
Bacteria that produce efflux pumps
Pseudomonas
Tetracycline resistance in E.Coli
Macrolide resistance in strep pneumonia
Microbe causing pseudoappendicitis syndrome
Yersinia enterolyticus
