An HIV-positive man with a CD4 count of 60 cells/mm3 has six months of profuse watery diarrhoea unresponsive to antibiotics. Stool modified acid-fast staining shows small round oocysts measuring 4 to 6 micrometres. The drug of choice for this infection is:
- A Metronidazole
- B Nitazoxanide ✓
- C Albendazole
- D Ivermectin
Correct answer: B. Nitazoxanide
Explanation
Cryptosporidium parvum oocysts stain pink-red on modified acid-fast staining and measure 4 to 6 micrometres, smaller than Cyclospora oocysts which measure 8 to 10 micrometres. Nitazoxanide is the drug of choice, though response in advanced immunosuppression is poor and antiretroviral therapy remains central to recovery. Metronidazole treats amoebiasis and giardiasis, albendazole targets helminths and microsporidia, and ivermectin is an antinematodal agent with no activity against coccidian protozoa.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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