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RACP > Infectious Disease > Flashcards

Infectious Disease Flashcards

1
Q

Treatment for MAC

A

Non-Tb Mycobacterium
- Azithromycin or Clarithromycin
- Rifampicin
- Ethambutol

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2
Q

IRIS

A

Immune reconstitution inflammatory syndrome
Parodoxical worsening of underlying infections at approx 1-2 months post-commencement of ART for HIV

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3
Q

Organisms not covered by Carbapenems

A

MRSA, enterococcus faecium, legionella, mycoplasma and chlamydia
Ertepenum does not cover Pseudomonas

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4
Q

CMV prophylaxis

A

Oral Valganciclovir
Required for all solid organ transplants;

D + / R - = 6 months
D - / R + = 3 months
D - / R - = no prophylaxis unless

Stem cell transplant if donor negative but host positive

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4
Q

CMV prophylaxis

A

Oral Valganciclovir
- Required for all solid organ transplants;
D + / R - = 6 months
D - / R + = 3 months
D - / R - = no prophylaxis unless

  • Stem cell transplant if donor negative but host positive
  • HIV with CD4 count < 50
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5
Q

Syphilis testing

A

Screening w trepenomal test;

  • TP-EIA IgM and IgG serology
  • TP-EIA will be confirmed in the lab against TPPA

Diagnosis w non-trepenomal tests

  • RPR - Used to confirm diagnosis of new infection, old infection or re-infection
  • VDRL - only used on CSF
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6
Q

Treatment of Syphilis

A

10 days of long-acting IM penicillin (Benzathine Penicillin)

Requires this longer acting penicillin to obtain continuous levels of penicillin to eliminate the treponemes which divide slowly.

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7
Q

Antigens involved in “Antigen Drift” in Influenza A

A

Glycoproteins
Glycoprotein H antigen - haemoagglutinin
Neuramindase N antigen

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8
Q

Live Vaccines

A

MMR
Polio
Yellow fever - uses eggs, can cause hypersensitivity reaction (along with Q fever vaccine)
Varicella Zoster
Mb BCG
Typhoid

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9
Q

Mechanism of MRSA

A

MecA gene - encodes additional penicillin binding proteins (PBP2) which cross-links the cell wall and leads to poor affinity of beta-lactams
Rx with Vancomycin if MIC < 2, or daptomycin if Vanc MIC > 2 (except for MRSA pneumonia where Daptomycin will be inhibited by surfactant -> use Linezolid)

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10
Q

Mechanism of VRE

A

Changes in cell wall components make it have low affinity for Vancomycin
Van A - Linezolid
Van B - Linezolid or Teicoplanin

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11
Q

Treatment of Tb Meningitis

A

12 month Rx with
- Izoniazid
- Rifampicin
- Pyrazinamide
- Moxifloxacin (better CNS penetration than ethambutol)

plus acute Dexamethasone use

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12
Q

Infectious causes of mesenteric adenitis

A

Yersinia from undercooked pork

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13
Q

Candida Krusei resistance

A

To Fluconazole

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14
Q

Active Tb treatment

A

2 months 4 drug regime;
Isoniazid
Rifampicin
Pyrazinamide
Ethambutol
followed by 4 months 2 drug regime;
Isoniazid
Rifampicin

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15
Q

Latent Tb Treatment

A
  • Isoniazid for 9 months
    or
  • Rifampicin for 4 months
    or
  • Isoniazid + rifampicin for 3 months
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16
Q

MRSA treatment

A

Vancomycin if MIC < 2

If Vanc MIC > 2 for Daptomycin or Linezolid

Choose Linezolid for pneumonia as daptomycin is inactivated by surfactant

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17
Q

Epstein Barr Virus

A

HHV 4

Proliferates in B cells and generates a CD8 T cell response -> can lead to lymphproliferative disorders

Causes
- Mononucleosis
- Burkitts
- Hairy Cell leukoplakiain HIV
- Cold agglutinin AIHA

Investigation
- Monospot (serology), early IgM -> late IgG
- EBNA gene production, delayed > 4 weeks

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18
Q

Dengue tests

A

Before 5 days;
- PCR
- NS1 protein Ag
After 5 days
- Antibodies IgM or IgG if > 10 days

Conservative management
Vaccination only for seropositive patients -> can worsen first infection in seronegative patients

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19
Q

Infections post-splenectomy

A

Strep pneumonia
Haemophilis Influenzae
Neisseria Meningitidis
Capnocytophaga canimorsus (dog bite)
Salmonella
Gram negative infections (E.Coli, Pseudomonas)

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20
Q

Bactericidal antibiotics

A

Very Finely Proficient At Cell Murder

Vancomycin
Fluroquinolones
Penicillin
Aminoglycosides
Cephalosporin, Carbapenem
Metronidazole

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21
Q

Bacterostatic antibiotics

A

ECSTaTiC

Erythromycin
Clarithromcyin
Sulfonamides
Trimethoprim
Tetracyclines
Chloramphenicol

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22
Q

Mechanism of Antibiotics

A

Beta-lactams and Vancomycin - cell wall inhibitors
Fluroquinolones - DNA Gyrase
Aminoglycosides and Tetracyclines - 30s ribosome
Trimethoprim & sulfonamides - Folate synthesis
Rifampicin - RNA polymerase
All others 50s ribosomal subunit

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23
Q

HIV opportunistic infection

A

> 200 - Shingles, pneumococcal, candida, Tb
< 200 - PJP
< 100 - Cryptococcus, Toxoplasmosis
< 50 - Disseminated MAC, CMV

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24
Q

Syphilis stages

A

Primary - Painless chancre and lymphadenopathy
Secondary - condyloma lata, contagious genital ulcers, mouth ulcers, uveitis
Tertitary - Neurosyphilis, aortitis, gumma.

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25
Q

Bacterial meningitis treatment

A

Emperic - Ceftriaxone + Benpen + Dex

Strep - Benpen or Ceftriaxone, add Vancomycin if Cef MIC > 1
Meningicoccus - Ceftriaxone
Listeria - Benpen

Dex only has benefit in Strep & H.Influenzae

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26
Q

Culture negative Endocarditis

A

Coxiella (Q fever)
Bortenella (Cat scratch)
Legionella
Chlamydia

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27
Q

Fever in returned traveller

A
  • Malaria - cyclical fevers without rash, myalgia, GI upset
  • Dengue - saddleback fevers and back pain, with macular rash
  • Zika Virus - mild illness with teratogenicity
  • Yellow Fever - acute hepatitis
  • Chikungunya - Severe joint pain
  • Typhoid/Paratyphoid - enteric fever- stepwise fevers with relative bradycardia and abdominal pain, rose spots
  • Enterotoxigenic E.Coli - acute diarrhoea illness
  • Giardia - delayed diarrhoea illness
  • Bacillus cereus bacteria - reheated rice within 6 hours (very early!)
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28
Q

HACEK group

A

Haemophilis, Aggregatibacter, Cardiobacterium, Eikenella, Kingella

Small gram negative bacteria that cause IE

29
Q

Major Dukes Criteria

A
  • Microbiology - ‘typical’ bugs in 2 separate blood cultures OR persistently positive culture of unusual organism
  • Echocardiogram - oscillating mass, abscess, new partial dehiscence of prosthetic valve OR new valvular regurgitation
  • Serology - for Coxiella (Q fever)
30
Q

Minor Dukes Criteria

A
  • Predisposition - IVDU or heart condition
  • Fever 38°C
  • Vascular phenomena - arterial embolism, septic pulmonary infarct, Janeway lesion, mycotic aneurysm, intracranial haemorrhage
  • Immunological phenomena - glomerulonephritis, Oslers nodes, Roth spots
  • Suggestive microbiology
31
Q

HIV Drugs

A

Nucleotide reverse transcriptase inhibitors - stop RNA to DNA transcriptase via binding at deoxynucleotide binding site

Non-nucleotide reverse transcriptase inhibitors - stop RNA to DNA transcriptase by binding at an alternative site to the deoxynucleotide

Integrase inhibitors - stop viral replicated DNA being integrated with host DNA

Protease inhihbitors - stop budding and maturation of virus from host cells, main role is to inhibit CYP3A4 to increase efficiency of other HIV drugs

32
Q

Linezolid side effects

A

Bone Marrow suppression with thrombocytopenia
Neuropathy
Serotonin syndrome

33
Q

Strongyloides

A

GI symptoms, dry cough, hyper infection decades after infection due to immunosuppression, larvae rash & organ failure due to infiltration or overlying bacterial infection
Worse with co-infection human T-lymphocytic virus 1 (HTLV1)
Ix - Serology or Rhabditiform larvae in stool
Rx Ivermectin

34
Q

Types of non-live vaccination

A

Conjugated (Ag bound to protein) - will induce a T cell response and long-term immunity

  • 13PCV pneumococcal - single dose to be given before non-conjugated
  • monovalent Menigicoccal - Against serotype C
  • Quadravalant Meningicoccal - Against serotypes A, C, W, Y
  • Meningococcal B

Unconjucated (Ag not bound to protein)- will only induce a B cell response, and no long term immunity

  • 23PPV pneumococcal - for 2 further doses to make up total 3 doses over 5 years
  • Haemophilus
35
Q

Antibiotic post-splenectomy

A

Amoxicillin for 3 years if otherwise healthy
Lifelong if Hx opportunistic infection

36
Q

Maleria treatment

A

Mild - 3 day course chloroquine followed by 14 day course Primaquine OR Artemether + lumefantrine
Latent - 14 days primaquine
Severe - IV Artesunate - resistance due to KELCH 13 gene in SE Asia

37
Q

Kelch 13

A

Mutation in malaria strains of SE asia which cause IV artesunate resistance

38
Q

Side effect Primaquine

A

If G6PD deficient, will cause haemolysis

39
Q

Mosquito’s which transmit disease

A

Anopheles - Malaria
Aedes - Flavivirus

40
Q

Antigen test for Dengue

A

NS1

41
Q

Zika virus complications

A

Teratogenic
Gullian Barre

Dx PCR < 7 days, serology > 7 days

42
Q

Typhoid

A

1-3 weeks incubation
Enteric fever due to Salmonella.
- Stepwise fevers
- diarrhoea or constipation w abdominal pain,
- Relative bradycardia
- Salmon coloured papule on skin (rose spots)
- Rx with Ceftriaxone.

43
Q

Mechanism of anti-fungals

A

Azoles - inhibit D-14 alpha demethylase at CP450 to stop ergosterol synthesis at cell walls

Echinocandins - inhibit beta 1,3 D glucan to inhibit cell wall synthesis

Amphotericin (polyenes) - binds ergosterol to stop membrane function and create pores

44
Q

How does HIV enter cells?

A

Via Glycoprotein 120 and glycoprotein 41 with co-receptors CCR5 (mild disease) and CXCR4 (late infection, more aggressive)

A lack of CCR5 causes a slower progression of disease

45
Q

HIV co-receptors on CD4 T cells

A

CCR5 - early
CXCR4 - late

Lack of CCR5 in populations causes slower and milder disease

46
Q

HIV co-receptors

A

CCR5 - early
CXCR4 - late

Lack of CCR5 in populations causes slower and milder disease

47
Q

HLAB57.01 and CCR5 mutation

A

Patients with HLAB57.01 MHC type receptors on CD4 cells bind strongly to T killer cells and & are more likely to be able to control viral load/slower progression of disease. These patients cannot be treated with Abacavir.

CCR5 co-receptor mutations - less ability of HIV to bind co-receptors causing slower progression of disease

48
Q

Time period and regime of HIV PEP

A

within 72 hours (best within 24 hours)

  • High risk - 2 x NRTI + integrase inhibitor (Known HIV not on treatment with detectable viral load or high risk exposure to unknown patient)
  • Low risk - 2 x NRTI (unknown HIV or on treatment with undetectable viral load)
49
Q

Starting ART after Tb Rx

A

CD4 count > 50 - wait 8 weeks
CD4 count < 50 - wait 2 weeks

50
Q

Antibiotics inhibiting 30S

A

Aminoglycosides (Gentamicin)
Tetracyclines (doxycycline)

51
Q

MOA Quinolones

A

I.e. Ciprofloxacin
Bind DNA gyrase

52
Q

MOA Rifampicin

A

Block RNA polymerase

53
Q

MOA Sulphonamides and Trimethoprim

A

Block folate synthesis

54
Q

MRSA resistance

A

Via mecA (mobile genetic element), which encodes for extra penicillin binding protein (PBP2a) that cross-links PBP and gives beta-lactams a lesser affinity

55
Q

ESCAPPM

A

Inducible beta-lactamase via AmpC
Enterobacter
Serratia
Citrobacter
Acinetobacter
Proteus Vulgaris (but not mirabilis)
Providencia
Morganella Morgani

56
Q

Enterobacter with Carbapenem resistance

A

New Delhi Metallo Beta Lactamase (NDM1) transferred by plasmids making enterobacter resistant to carbepenams

57
Q

Genes for antibiotic resistance

A

MRSA - genetic mobile unit MecA
VRE - plasmid Van A, B, C
ESBL - plasmid CTX-M
ESCAPPM - inducible betalactamase AmpC
CRE - plasmid New Delhi Metallo (NDM1) beta lactamase

58
Q

Empirical Rx for Nec Fasc

A

Meropenum, Vancomycin and Clindamycin (for toxins)

59
Q

Side effects of Rifampicin

A

CYP inducer (particularly important in HIV meds)
Hepatotoxicity
Orange sercretions

60
Q

Side effects of Isoniazid

A

Hepatotoxicity, Peripheral neuropathy

61
Q

Side effect of Ethambutol

A

Optic neuropathy - require baseline eye tests

62
Q

Side effects of Pyrazinamide

A

Gout, Hepatotoxicity

63
Q

Major side effects of Tb Medications

A

Rifampicin - CYP inducers, orange secretions
Isoniazid - Peripheral Neuropathy (give w B6 Pyridoxine)
Ethambutol - Optic neuropathy
Pyrazinamide - Gout, Worst risk of hepatitis!

64
Q

Which cohorts to treat latent Tb

A

Healthcare workers
< 35 years old
Immunosuppressed
Recent infection

65
Q

CMV

A
  • Mononucleosis- type illness with Fever and Lymphadenopathy “CMV-effect”
  • Can affect many end organs “CMV disease” ( Pneumonia, hepatitis, GBS, Meningoencephalitis, myocarditis, thrombocytopenia, haemolytic anaemia)
  • Owl eyes on blood film
  • Risk of maternal -> fatal transmission 40%
66
Q

Risk of CMV in transplant

A

Solid organ - Donar +, recipient -
Haematological - Donar -, recipient +

67
Q

Commonest organism to cause IE

A

Staph Aereus
Or
Staph Epi if within 2 months of prosthetic heart valve

68
Q

MRO resistance mechanisms

A

MRSA - MecA gene causing change in penicillin binding protein 2

VRE - Van A or B causing change in cell wall to reduce affinity for Vancomycin

ESBL - Plasma mediated genes which code for enzyme that hydrolyses bea-lactam, most commonly CTX-M gene. Causes resistance to penicillins & 3rd generation cephalosporins (Ceftr, Ceftaz)

ESCAPPM - ESBL with inducible beta-lactamase on Chromosomal AmpC (not plasmid)

CRE - Carbapenem resistant beta-lactamase - New Delhi Metallo-beta-lactamase-1 (NDM1) on plasmids

69
Q

Types of Candida & Rx

A

Candida albicans - fluconazole (most common)
Candida glabrata - Echinocandin
Candida Krusei - Voriconazole (fluconazole resistance)
Candida Auris - Echnocandin (known multi-drug resistance)

RACP (17 decks)

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