Question:medium
The drug of choice (DOC) for Isospora (Cystoisospora) infection is:
The drug of choice (DOC) for Isospora (Cystoisospora) infection is:
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An antifolate antibiotic, not a penicillin, clears this coccidian.
Updated On: Jun 23, 2026
- Penicillin G
- Benzathine penicillin
- Co-trimoxazole
- Albendazole
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The Correct Option is C
Solution and Explanation
Step 1: Identify the bug class - Cystoisospora belli is an intestinal coccidian protozoan, often seen in HIV-related chronic diarrhea.
Step 2: Coccidia respond to antifolate therapy, and the standard first-line agent is co-trimoxazole (trimethoprim plus sulfamethoxazole), known by brands such as Bactrim or Septra.
Step 3: A common course is $160/800\,mg$ orally twice daily for about 7 to 10 days, extended in immunosuppressed hosts.
Step 4: The penicillins target bacteria and albendazole targets worms, so they cannot clear a protozoal coccidian, leaving co-trimoxazole as the choice.
\[\boxed{\text{Co-trimoxazole}}\]
Step 2: Coccidia respond to antifolate therapy, and the standard first-line agent is co-trimoxazole (trimethoprim plus sulfamethoxazole), known by brands such as Bactrim or Septra.
Step 3: A common course is $160/800\,mg$ orally twice daily for about 7 to 10 days, extended in immunosuppressed hosts.
Step 4: The penicillins target bacteria and albendazole targets worms, so they cannot clear a protozoal coccidian, leaving co-trimoxazole as the choice.
\[\boxed{\text{Co-trimoxazole}}\]
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