Respiratory TB

Question 1

Which antibiotics should TB be treated with for the first two months?

Answer 1

First two months:

• rifampicin
• isoniazid
• pyrazinamide
• ethambutol

Question 2

Which antibiotics should TB be treated with for months 2-6?

Answer 2

Months 2-6:

• rifampicin
• isoniazid

Question 3

side effects of Rifampicin?

Answer 3

• colours urine and all body fluids orange
• is a potent inducer of cytochrome enzymes (so rapid breakdown of all steroid hormones including hormonal contraception, similar breakdown of opiate analgesics and other drugs)

Question 4

side effects of ethambutol?

Answer 4

-can cause optic neuritis (inflammation of the optic nerve)

Question 5

Single agent drug resistance in TB

Answer 5

commonly to isoniazid

Question 6

multi-drug resistance in TB

Answer 6

resistance to rifampicin and isoniazid

Question 7

Extensive drug resistance in TB

Answer 7

multi-drug resistance (rifampicin and isoniazid) and also quinolones and injectable (a type of contraception?)

Question 8

Name 2 tests which test for previous exposure to TB

Answer 8

• interferon gamma release assay (a blood test)

- mantoux (tuberculin) test (a skin test)

Question 9

Mantoux AKA tuberculin skin test

Answer 9

• requires 2 visits (patient has to return to see if there has been a delayed hypersensitivity reaction at site of injection)
• intradermal injection
• detects previous exposure to either TB or BCG - so can give false positives
• cannot distinguish between latent TB, cured TB, active TB, and BCG
• reaction may be diminished in IC patients

Question 10

interferon gamma release assay (IGRA)

Answer 10

This assay looks for interferon gamma specific to antigens found only in mycobacteria tuberculosis. It doesn’t react with BCG.

• only requires 1 visit
• high sensitivity

Question 11

Anti-TNF therapy is used for patients with Crohn’s, rheumatoid, psoriasis, ankylosing spondylitis. Why should you look for latent TB before prescribing anti-TNF therapy?

Answer 11

Anti-TNF therapy can cause re-activation of latent TB - usually within the first 12 weeks
If patient has latent TB: they should be given 6 months of isoniazid or 3 months of isoniazid and rifampicin also.

Question 12

BCG vaccine

Answer 12

• it’s an attenuated strain of mycobacterium bovis
• intradermal injection
• most effective in neonates of high risk families
• also provides some protection against leprosy

Question 13

What other infection should all TB patients be tested for?

Answer 13

HIV

Also: all HIV cases should be offered a chest x-ray to check for TB

Question 14

steroids and immunosuppressive drugs can reactivate latent TB. True/ False?

Answer 14

True