Pulmonary Tuberculosis

Question 1

Who should be screened for TB disease and infection?

Answer 1

• 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)

Question 2

Difference between TB disease and TB infection?

Answer 2

TB infection: latent TB, infected but not contagious and no sx
TB disease: infected, contagious, have sx

Question 3

What are the lab tests to diagnose TB infection in adults?

Answer 3

• Interferon-gamma release assays
• alternative: tuberculin skin tests (cut-off is 10mm; 5mm for immunocompromised)

Question 4

What are the lab tests to diagnose TB infection in children?

Answer 4

• ≥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)

Question 5

What baseline tests should be performed before starting TB infection treatment?

Answer 5

• rule out TB disease with symptom screen & chest X-ray
• AST & ALT (LFT) [also monitoring]

Question 6

What are the preferred regimens for TB infection treatment?

Answer 6

• Rifampicin (<10y: 15mg/kg; if not 10mg/kg) daily for 4m OR
• Isoniazid (<10y: 10mg/kg, if not 5mg/kg) daily for 6/9m

Question 7

What are the alternative regimen for TB infection treatment in adults?

Answer 7

• Rifampicin & isoniazid daily for 3m

Question 8

What is recommended to be taken if pt is on isoniazid-containing regimen and why?

Answer 8

Pyridoxine supplementation (10-25mg), reduce risk of isoniazid-induced peripheral neuropathy

Question 9

Why prefer to use isoniazid daily 6/9m regimen for HIV pts?

Answer 9

Due to rifampicin DDI with antiviral therapy

Question 10

If drug therapy is interrupted due to hepatotoxicity, is it okay to restart therapy?

Answer 10

Can once liver function has normalised (infection) or liver enzymes return to <2x ULT (disease)

Question 11

When to follow-up on TB infection treatment?

Answer 11

4-6 weeks

Question 12

What tests should be done to diagnose TB disease?

Answer 12

• Hx taking & examination
• Chest x-ray
• Acid-fast bacilli smear microscopy
• Nucleic acid amplification test (NAAT)
• Mycobacterial culture

Question 13

What clinical sample should be collected for testing? How many?

Answer 13

Sputum (at least 2, one should be an early morning sample and both should be on the same day)

Question 14

What is the preferred regimen for treatment of TB disease in adults?

Answer 14

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

Question 15

What is the preferred regimen for treatment of TB disease in children?

Answer 15

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

Question 16

When to follow up for TB disease?

Answer 16

2-4 weeks during intensive phase, 4-6 weeks during continuation phase

Question 17

What to follow up at baseline and subsequent monitoring for TB disease?

Answer 17

• chest x-ray, acid-fast bacilli (baseline, after intensive, after continuation)
• visual assessments for ethambutol (baseline, subsequent visits)
• LFT, renal function, FBC (baseline)

Question 18

What are the 4 main drugs used for TB?

Answer 18

Rifampicin, isoniazid, pyrazinamide, ethambutol

Question 19

Which TB drugs cause GI SE and what kind?

Answer 19

Rifampicin, isoniazid, pyrazinamide
anorexia, nausea, abd pain -> take after meal

Question 20

Which drug is a drug inducer and what drugs does it interact with?

Answer 20

Rifampicin: warfarin, corticosteroids, COC, HIV protease inhibitors

Question 21

SE of rifampicin? (5)

Answer 21

• 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)

Question 22

Which drugs do not require renal impairment dose adjustment?

Answer 22

Rifampicin, isoniazid -> hepatically cleared

Question 23

Which drugs should be spaced apart from antacids by 2h and why?

Answer 23

• Isoniazid -> antacids delay absorption by increasing gastric pH
• Ethambutol -> antacids reduce max serum conc

Question 24

Which drug is a drug inhibitor?

Answer 24

Isoniazid (CYP450)

Question 25

SE of isoniazid? (2)

Answer 25

• peripheral neuropathy
• hepatitis

Question 26

Which drugs are prodrugs?

Answer 26

Isoniazid, pyrazinamide

Question 27

Rank the TB drugs based on hepatotoxicity? (least to most)

Answer 27

Ethambutol < rifampicin < isoniazid < pyrazinamide

Question 28

SE of pyrazinamide?

Answer 28

• GI (N/V)
• photosensitivity
• hepatotoxicity
• hyperuricaemia & arthralgia (inhibit uric acid excretion)
• widespread rashes & pruritus

Question 29

SE of ethambutol?

Answer 29

• visual toxicity
• hyperuricaemia/gout -> reduced uric acid excretion

Question 30

Alternative treatment for TB disease in adults?

Answer 30

• 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