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competency 10/11 > id: tb > Flashcards

id: tb Flashcards

(50 cards)

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1
Q

mycobacterium tuberculosis

A

obligate aerobic, slow-growing, acid-fast bacilli
waxy cell membrane: does not produce a typical gram-stain response (requires acid-fast stain to visualise)

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2
Q

risk factors for latent and active tb

A
  • residents of prisons, homeless shelters, nursing homes
  • close contact with pulmonary tb pt
  • co-infection with hiv
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3
Q

risk factors for active tb

A
  • children<2yo
  • elderly>65yo
  • malnutrition
  • immunosuppression
  • co-infection with hiv
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4
Q

s/sx of tb

A
  • productive cough
  • hemoptysis
  • fever
  • fatigue
  • night sweats
  • weight loss
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5
Q

radiological findings for tb

A

infiltrates in the apical region, cavitary lesions

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6
Q

pneumonia vs tb, in terms of clinical presentation

A

tb gradual onset (over weeks-months) vs pneumonia acute onset (over hours-days)

tb infiltrates in the apical region vs pneumonia in the middle/lower lobes

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7
Q

indication for latent tb infection screening

A

high-risk group and intent to treat if pos:
- children with recent tb contact
- hiv-infected indiv
- pt considered for tumor necrosis factor antagonist therapy
- transplant pt
- dialysis pt

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8
Q

latent tb diagnosis tests

A
  1. tuberculin skin test
  2. interferon-gamma release assay
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9
Q

tuberculin skin test: pros and cons

A

+ high sensitivity (95-98%)
+ low cost
+ no need to collect blood samples

  • false neg: immunocompromised
  • false pos: envi contact w non-tb mycobacteria, bcg vaxx
  • no universally accepted standards for interpreting results
  • inter-reader variability
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10
Q

interferon-gamma release assay: pros and cons

A

+ performance as good as PPD
+ no false pos in bcg-vaxx indiv
+ minimal cross-reactivity with non-tb mycobacteria
+ results avail within few hrs

  • more ex
  • need for blood samples
  • false neg: immunocompromised
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11
Q

most sg residents are bcg-vaxx: positive tuberculin skin tests >=

A

10mm

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12
Q

prior to treatment for latent tb

A

exclude active tb

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13
Q

latent tb treatment regimen: isoniazid

A

5mg/kg/d
max 300mg daily
x6mths or 9mths(hiv)

  • preferred regimen, especially in pregnancy/lactation/hiv
  • co-adm with pyridoxine (at least 10mg/d) to minimise neuropathy
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14
Q

isoniazid must be co-adm with

A

pyridoxine (at least 10mg/d) to minimise neuropathy(b6 deficiency)

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15
Q

latent tb treatment regimen: rifampicin

A

10mg/kg/d
max 600mg daily
x4mths

  • alt in pt who cannot tolerate isoniazid
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16
Q

latent tb treatment regimen: isoniazid + rifapentin

A

900mg PO weekly
x12wk

  • must be given under DOT
  • not recommended for hiv pt
  • limited clinical experience and evidence to date
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17
Q

standard 6 month active tb treatment

A

intensive phase: 2 months
- daily: RIPE/STM

continuation phase: 4 months
- daily or 3x/wk adm: RI

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18
Q

culture neg

A

does not imply that pt does not have tb
- mycobacterium tb is difficult to grow on culture

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19
Q

pyrazinamide

A

15-30mg/kg daily
max 2g
500mg tab

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20
Q

ethambutol

A

15-25mg/kg/d
max 1.6g
100,400mg tablet

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21
Q

streptomycin

Study These Flashcards
A

IM 10-15mg/kg daily
max 1g

22
Q

rifampicin

Study These Flashcards
A

10mg/kg/d or 3x/wk
max 600mg
100,300mg tab

23
Q

isoniazid

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A

5mg/kg/d, max 300mg
15mg/kg 3x/week, max 900mg
150,300mg tab

24
Q

tb drugs that req renal dose adj

25
if unlikely to tolerate PZA eg. elderly or liver disease
standard 9-month: - intensive phase, 2 months, daily RIE - continuation phase, 7mths, daily or 3x/week RI
26
tb meds exhibit
conc-dependent killing > once-daily
27
risk factor for hepatotoxicity
- age>35yo - female - underlying liver disease - concurrent alcohol use - hiv
28
sx of hepatotoxicity
- n/v - abdominal discomfort or pain - unexplained fatigue
29
if have risk factor for hepatotoxicity, lft monitoring
at baseline and every 2-4 weeks
30
hepatotoxicity development
ALT>3xULN w sx or ALT>5xULN wo sx
31
if hepatotoxicity develops in latent tb tx
- stop tx imm - monitor lfts - rechallenge with inh when alt improves to <2xULN - if pt cannot tolerate inh, switch to rifx4mths
32
if hepatotoxicity develops in active tb treatment
- stop tx imm - monitor lfts - rechallenge sequentially when lfts normalised and sx resolved - if re-challenge fails, may need non-hepatotoxic regimen eg. ETM+FQ+STM
33
EMB can cause
visual toxicity - reduced visual acuity - reduced red-green colour discrimination monitor visual acuity and colour discrimination test: - at baseline for all pt - monthly in pt w any 2 risk factors: taking etm >2 months, has renal insufficiency eg ckd
34
treatment of tb needs to be prolonged to ensure
killing of these slowly growing/semi-dormant org - if not fully eradicated, might cause relapse
35
for active tb treatment, pt's ___ should be documented at each visit
weight, and have drug dosages adj accordingly
36
adr of RIP
gi: anorexia, nausea, abdominal discomfort - to adm after a light meal or before bedtime - exclude hepatotoxicity if sx sevre and persisitent
37
adr of all first line anti-tb drugs
cutaneous reactions: pruritis - self-limiting
38
as a precaution, rfiampicin should be given with ____ to mothers and neonates born to monthers who have been under treatment w rifmapicin
vit K, avoid postpartum hemorrhage (adr a/w rifampicin is thrombocytopenia)
39
isoniazid metabolism
in the liver, through acetylation by N-acetyltransferase - acetylation rate related to genetic polymorphism: certain pt eg chinese in sg: rapid acetylator phenotype vs indians (slow)
40
isoniazid should not be taken concomittantly with foods
rich in tyramine and histamine: - certain types of fish (tuna) - cheese and red wine may give rise to SE such as flushing and headache
41
isoniazid/etm and antacids
antacids incr gastric pH and delay absorption of isoniazid/etm - separate from isoniazid/etm ingestion by 2 hrs
42
isoniazid ddi
may incr conc of anticonvulsants eg phenytoin and oral anticoagulants
43
which anti-tb drug most effective in eliminating persisters?
pyrazinamide
44
pyrazinamide and gout-like sx
pyrazinoic acid, principal metabolite of pyrazinamide, inhibits renal tubular secretion of uric acid and results in gout-like sx
45
ethambutol and gout
reduce excretion of uric acid by kidney
46
adr of streptomycin
ototoxicity, neurotoxicity, nephrotoxicity
47
cure
neg sputum smear or culture in last month of tx and on at least one prev occasion
48
tx failure
pos sputum bacteriology at or after 5 months of treatment
49
non-conversion of sputum cultures at __ months is a good surrogate marker for risk of relapse
2
50

competency 10/11 (31 decks)

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