Paper II — 2024 December (Supplementary) (2019 Scheme) — Q4
3 min read
Paper II
2024 December (Supplementary) (2019 Scheme) · 100 marks · 180 min
Question
Explain prophylactic use of antimicrobials giving suitable examples.
Q46 marksShort Essays
Answer
Prophylactic (chemoprophylactic) use of antimicrobials means giving a drug to prevent an infection before it establishes, rather than to treat one already present — rational only when a specific, predictable pathogen is anticipated and a specific, time-limited drug/duration is used, not indefinite broad-spectrum cover.
Examples with rationale:
Surgical prophylaxis — a single dose of an appropriate agent (e.g. Cefazolin), timed to peak at the time of incision, covering organisms likely to contaminate that surgical site; continued only briefly, since prolonged prophylaxis adds resistance/toxicity risk without added benefit.
Contact prophylaxis — Rifampicin or Ciprofloxacin for close contacts of meningococcal meningitis, targeting the specific organism the index case demonstrated.
Rheumatic fever recurrence prevention — Benzathine penicillin, monthly IM, continued for years, preventing recurrent streptococcal pharyngitis from triggering further rheumatic carditis.
Malaria chemoprophylaxis — Chloroquine/Doxycycline for travelers to endemic areas.
Isoniazid prophylaxis — in close contacts of active TB or latent TB infection.
Perinatal prophylaxis — antiretrovirals to prevent mother-to-child HIV transmission.
The unifying principle: a defined exposure or high-risk period, a specific anticipated organism, and a defined, limited duration — indefinite “just in case” antimicrobial use is not chemoprophylaxis.
