Tuberculosis Flashcards
What are the risk factors for TB? (4)
Immigrants from countries with high rates of TB (Africa, South America, Asia)
Immunodeficiency - HIV, drugs (e.g. anti-TNFs, steroids), transplant, steroids
Chronic diseases: diabetes, CKD, Chronic liver (cirrhosis), chronic lung disease (silicosis, COPD), malnutrition, malignancy
Substance use: Smoking, alcohol, drug use
TB - history?
P: symptoms, diagnosis date
Risk factors - contact, recent immigrant, ImmSx, chronic disease, substances, had BCG (at what age)?
I: How was it dx? CXR/CT, Mantoux/IGRA screening, TB sputum culture (having to give early morning sputum), Bronchoscopy/BAL
C: compliance - how is the drug administered (TB clinic - supervised vs. self)
M: Tx history - in detail. Doses, duration, previous treatments and resistance
C:
- complications of drugs - optic neuritis (eye pain), ototoxicity, hepatitis, renal impairment, PN,
- complications of disease (RF, ICU admissions)
Prognosis/current Progress
- Current state: symptoms, ET, frequency of FU, plan for the future.
- Insight into the disease - especially regarding public health
- How is patient affected - stigma, bothersome DOT, work/life...etc
- Public Health: does patient’s occupation involve a public health risk? - how is this handled? Did patient’s family & friends have screening? Is anyone else being treated?
IGRA +ve means what?
It is a diagnostic test for latent TB infection.
It cannot distinguish between latent vs active TB disease.
Negative IGRA does not rule out active TB at any stage.
What constitutes a positive tuberculin skin test (TST/Mantoux)?
≥5mm (High-Risk)
- Abnormal CXR consistent with prior TB
- Close contact with documented case
- ImmSx - transplant, HIV, pred ≥15mg/d
≥10mm (intermediate-risk) - all other at-risk groups, i.e.
- Health Care Workers
- From countries with high prevalence
- Pred <15mg/d
- Inmates, IVDU
- Diabetic (remember it is a risk factor for TB development)
≥15mm in all other patients.
When would you choose IGRA (interferon gamma release assay) over TST?
When patient had BCG vaccination as they are less likely to return to have TST read.
Rifampicin - usual daily dose and 3 side effects?
600mg/day.
RifamPicin
Red-orange urine
P450 inducer
Hepatitis
Isoniazid - 3 side effects + daily dose
INH - 300mg (reduce the dose in CKD to 2-3 times per week)
Iron accumulation in mitochondria → sideroblastic anaemia
Neuropathy (peripheral) - give vitamin B6 (Pyridoxine)
Hepatitis
Ethambutol usual dose and side effect (1)?
15mg/kg.
Ethambutol = Eye problems
Optic neuritis, decreased acuity + red/green discrimination
Pyrazinamide usual dose and side effects (2)?
1.5 - 2g / day
PyRAZinamide - Raise uric acid - Gout
Hepatitis
PAS (Para-Aminosalicylic Acid) - purpose, dose and 3 side effects?
12g.
Hepatitis
Diarrhoea
Hypersensitivity
Streptomycin side effects (2) and dose?
StReptOmycin
Ototoxicity
Renal impairment
1g/day - contraindicated in pregnancy
TB - exam finding to report?
General: Cachexia & wasting
Chest: upper-lobe coarse crackles/wheezes due to partial bronchial obstruction by lymphadenopathy
Amphoric breath sound (rare)
Extra-pulmonary (LN, Heart, Abdo, Renal, Bones)
Lymphadenopathy (especially in HIV patient) - most common
TB pericarditis - say no muffled breath sounds to suggest tamponade
Abdominal mass - say no evidence of TB peritonitis (severe tenderness)
Renal angle tenderness (GU involvement)
Pott’s - lumbar spine/Hips/Knees
Positive TST (or IGRA) but no active disease on CXR and sputum for AFB. What is your management?
A careful approach to balancing the risk of disease vs. risk of treatment. Especially in elderly ≥65 (risk increases from 50) given risk of serious hepatotoxicity - there is linear relationship between the two.
Regime is usually INH for 9 months (90% never re-activate)
Causes for false -ve TST? (4)
ImmuSx
Elderly (re-check after 3 weeks)
Miliary TB (50%)
Recent exposure (re-check after 12 weeks)
Does QuntiFERON GOLD assay positivity always indicate TB infection? If IGRA -ve, does it mean that patient does not have TB?
No - false +ve can occur with other atypical mycobacteria. 98% specificity.
False -ve also occur, as sensitivity is only 80-85% (not a great NPV)