Question:
A 46-year-old woman with HIV has severe persistent diarrhoea. On histological investigation, which organism is most likely causing the diarrhoea?
A 46-year-old woman with HIV has severe persistent diarrhoea. On histological investigation, which organism is most likely causing the diarrhoea?
Show Hint
Chronic watery diarrhoea plus low CD4, look for the acid-fast protozoan hugging the enterocyte brush border.
Updated On: Jun 23, 2026
- Cryptosporidium
- Staphylococcus aureus
- Salmonella
- Clostridium botulinum
Show Solution
Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Answer: Cryptosporidium.
Step 1: Severe, persistent, watery diarrhoea in an HIV or AIDS patient, especially with a low CD4 count, points strongly to an opportunistic intestinal parasite.
Step 2: Cryptosporidium parvum is the classic offender. It is a coccidian protozoan whose oocysts are acid-fast on modified Ziehl-Neelsen stain, and on intestinal histology the organisms sit at the apical brush border of the enterocytes, a recognisable diagnostic clue.
Step 3: The distractors do not fit a chronic AIDS-related diarrhoea diagnosed on histology: Staphylococcus aureus gives acute toxin-mediated vomiting, Salmonella gives an acute self-limited or invasive enterocolitis, and Clostridium botulinum causes paralysis, not diarrhoea.
Ref: Standard parasitology and HIV-medicine texts.
Step 1: Severe, persistent, watery diarrhoea in an HIV or AIDS patient, especially with a low CD4 count, points strongly to an opportunistic intestinal parasite.
Step 2: Cryptosporidium parvum is the classic offender. It is a coccidian protozoan whose oocysts are acid-fast on modified Ziehl-Neelsen stain, and on intestinal histology the organisms sit at the apical brush border of the enterocytes, a recognisable diagnostic clue.
Step 3: The distractors do not fit a chronic AIDS-related diarrhoea diagnosed on histology: Staphylococcus aureus gives acute toxin-mediated vomiting, Salmonella gives an acute self-limited or invasive enterocolitis, and Clostridium botulinum causes paralysis, not diarrhoea.
Ref: Standard parasitology and HIV-medicine texts.
Was this answer helpful?
0
0
Top NEET PG Microbiology Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions
Top NEET PG Opportunistic infections in HIV Questions
Top NEET PG Questions
- A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- Which of the following statements is true about Trichomonas vaginalis?
- A lady from West Rajasthan presented with an ulcer surrounded by erythema on the right leg. Microscopy of the biopsy from the edge of the ulcer showed organisms with dark staining nuclei and kinetoplast. What is the most likely causative agent?
- A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- Infection with Clonorchis sinensis is associated with an increased risk of__?
View More Questions