TB

Question 1

Quantiferon gold assay

Answer 1

Expose whole blood to TB antigens
• ESAT-6, CFP-10

• Sensitised lymphocytes release measurable
cytokines in response
• Also test response to mitogen and to nothing
• Does NOT differentiate Latent vs. Active TB
• Fewer false +ves caused by BCG, atypicals
• Potentially from M. marinum, M. kansasii & M. szulgai

Question 2

Significant risks of reactivation of latent TB include all
the following except:
• A. HIV infection
• B. Cancer chemotherapy
• C. Alcohol abuse
• D. Corticosteroid use
• E. Anti-TNF therapy
• F. Diabetes mellitus
• G. End stage renal failure
• H. Cigarette smoking

Answer 2

• C. Alcohol abuse

Question 3

Features of RIPE

Answer 3

• Rifampicin is a bacteriocidal anti TB drug that kills both multiplying and dormant bacteria hence it sterilizes the tissue.
• INH is effective against multiplying bacilli.
• Ethambutol in low dose is bacteriostatic and in high dosages, is bacteriocidal.
• Pirazinamide is a mild bacteriocidal drug but has a property of killing bacilli in acidic environment such as, in macrophages and areas of acute inflammation. It can cross blood brain barrier in good concentration