Pulmonary Tuberculosis Flashcards
Who should be screened for TB disease and infection?
- HIV pts
- close contacts of pts with TB
- ppl with clinical risk factors (anti-TNF therapy, steroids = ≥15mg prednisolone for >8w, organ transplant, dialysis, silicosis)
Difference between TB disease and TB infection?
TB infection: latent TB, infected but not contagious and no sx
TB disease: infected, contagious, have sx
What are the lab tests to diagnose TB infection in adults?
- Interferon-gamma release assays
- alternative: tuberculin skin tests (cut-off is 10mm; 5mm for immunocompromised)
What are the lab tests to diagnose TB infection in children?
- ≥5y or ≥2y with BCG vaccine: interferon-gamma release assays
- 2-5y without BCG vaccine: tuberculin skin test or interferon-gamma release assay
- 6m-<2y: tuberculin skin test (cut-off is 10mm; 5mm for immunocompromised)
What baseline tests should be performed before starting TB infection treatment?
- rule out TB disease with symptom screen & chest X-ray
- AST & ALT (LFT) [also monitoring]
What are the preferred regimens for TB infection treatment?
- Rifampicin (<10y: 15mg/kg; if not 10mg/kg) daily for 4m OR
- Isoniazid (<10y: 10mg/kg, if not 5mg/kg) daily for 6/9m
What are the alternative regimen for TB infection treatment in adults?
- Rifampicin & isoniazid daily for 3m
What is recommended to be taken if pt is on isoniazid-containing regimen and why?
Pyridoxine supplementation (10-25mg), reduce risk of isoniazid-induced peripheral neuropathy
Why prefer to use isoniazid daily 6/9m regimen for HIV pts?
Due to rifampicin DDI with antiviral therapy
If drug therapy is interrupted due to hepatotoxicity, is it okay to restart therapy?
Can once liver function has normalised (infection) or liver enzymes return to <2x ULT (disease)
When to follow-up on TB infection treatment?
4-6 weeks
What tests should be done to diagnose TB disease?
- Hx taking & examination
- Chest x-ray
- Acid-fast bacilli smear microscopy
- Nucleic acid amplification test (NAAT)
- Mycobacterial culture
What clinical sample should be collected for testing? How many?
Sputum (at least 2, one should be an early morning sample and both should be on the same day)
What is the preferred regimen for treatment of TB disease in adults?
2 month intensive phase of
- isoniazid daily (5mg/kg) or thrice weekly (10mg/kg)
- rifampicin daily (10mg/kg) or thrice weekly (10mg/kg)
- pyraziamide (20-25mg/kg) daily or thrice weekly (30-40mg/kg)
- ethambutol (15-20mg/kg) daily or thrice weekly (25-40mg/kg)
then 4 month continuation phase of isoniazid and rifampicin daily or thrice weekly
+ pyridoxine taken same time as the rest
What is the preferred regimen for treatment of TB disease in children?
2 month intensive phase of
- isoniazid daily (10-15mg/kg, max 300mg) or thrice weekly (20mg/kg)
- rifampicin daily (15-20mg/kg, max 600mg) or thrice weekly (20mg/kg)
- pyraziamide (30-40mg/kg, max 2g) daily
- ethambutol (15-25mg/kg, max 1g) daily
then 4 month continuation phase of isoniazid and rifampicin
When to follow up for TB disease?
2-4 weeks during intensive phase, 4-6 weeks during continuation phase
What to follow up at baseline and subsequent monitoring for TB disease?
- chest x-ray, acid-fast bacilli (baseline, after intensive, after continuation)
- visual assessments for ethambutol (baseline, subsequent visits)
- LFT, renal function, FBC (baseline)
What are the 4 main drugs used for TB?
Rifampicin, isoniazid, pyrazinamide, ethambutol
Which TB drugs cause GI SE and what kind?
Rifampicin, isoniazid, pyrazinamide
anorexia, nausea, abd pain -> take after meal
Which drug is a drug inducer and what drugs does it interact with?
Rifampicin: warfarin, corticosteroids, COC, HIV protease inhibitors
SE of rifampicin? (5)
- cutaneous syndrome (flushing +/ pruritus, with/without rash, redness & watering of eyes)
- flu-like syndrome (fever, chills, HA, malaise)
- respiratory syndrome (SOB)
- hepatitis
- orange discolouration of body fluids (tears, sweat, urine)
Which drugs do not require renal impairment dose adjustment?
Rifampicin, isoniazid -> hepatically cleared
Which drugs should be spaced apart from antacids by 2h and why?
- Isoniazid -> antacids delay absorption by increasing gastric pH
- Ethambutol -> antacids reduce max serum conc
Which drug is a drug inhibitor?
Isoniazid (CYP450)
SE of isoniazid? (2)
- peripheral neuropathy
- hepatitis
Which drugs are prodrugs?
Isoniazid, pyrazinamide
Rank the TB drugs based on hepatotoxicity? (least to most)
Ethambutol < rifampicin < isoniazid < pyrazinamide
SE of pyrazinamide?
- GI (N/V)
- photosensitivity
- hepatotoxicity
- hyperuricaemia & arthralgia (inhibit uric acid excretion)
- widespread rashes & pruritus
SE of ethambutol?
- visual toxicity
- hyperuricaemia/gout -> reduced uric acid excretion
Alternative treatment for TB disease in adults?
- isoniazid 5mg/kg daily or 10mg/kg 3x/week
- pyrazinamide 20-25mg/kg daily or 30-40mg 3x/week
- rifapentine 1200mg daily
- moxifloxacin 400mg daily
8 weeks intensive of all, then 9 week continuation of I, P, M
+ pyridoxine
