Insights into gastrointestinal manifestation of human immunodeficiency virus: A narrative review

Table 2 Common opportunistic pathogens in human immunodeficiency virus-associated diarrhea-location, presentation, diagnosis and treatment

Pathogen	Location	Clinical features	Diagnosis	Chemoprophylaxis	Treatment
Cytomegalovirus	Gastric, small bowel (ileum), and large bowel (colon)	Bloody diarrhea, fever, weight loss, fever, anorexia, abdominal pain	DNA PCR from stool sample	None recommended	IV ganciclovir for 21 to 42 days (can with to oral valganciclovir once the patient can tolerate)
Herpes simplex	Anorectal	Tenesmus, rectal pain, hematochezia, proctitis	DNA PCR for cutaneous lesion	None recommended	Acyclovir/Valacyclovir PO for 5 to 10 days
Cryptosporidium	Gastric, small bowel (ileum), and large bowel	Acute/Subacute onset watery diarrhea, nausea/vomiting, lower abdominal cramping	Microscopic identification of the oocysts in stool with acid-fast staining or direct immunofluorescence	None recommended	Nitazoxanide (500/1000 mg POD BID for 14 days) or paromomycin (500 mg PO QID for 14 to 21 days)
Microsporidia	Small and large bowel	Diarrhea with cramps and abdominal pain, wasting, malnutrition	Microscopic identification of the spores in stool with trichrome staining	None recommended	For Enterocytozoon bieneusi–nitazoxanide 500 mg BID for 14 days. For intestinal infection caused by microsporidia other than E. bieneusi–albendazole 400 mg BID for 14 days
Isospora belli	Gastric	Watery diarrhea, with abdominal pain, cramping, nausea/vomiting, low-grade fever, dehydration	Microscopic identification of the oocysts in stool with acid-fast staining or UV fluorescence microscopy	None recommended. Indirect evidence of a protective effect of TMP-SMX	TMP-SMX (160/800mg QID for 10 days)
Cyclospora	Small bowel	Watery diarrhea, weight loss, abdominal cramping, low-grade fever	Microscopic identification of the oocysts in stool with acid-fast staining	None recommended	TMP-SMX (160/800 mg PO BID for 14 days) or nitazoxanide (500 mg PO BID for 7 days)
Entamoeba histolytica	Colon	Diarrhea with blood and mucus, cramping lower abdomen pain, bloating, fever, chills	DNA PCR from stool sample, stool antigen test, microscopic identification of the cysts/trophozoites in stool	None recommended	Metronidazole 500-750 mg PO TID for 5-10 days or tinidazole 2 g PO once daily for 3 days, followed by a luminal agent
Histoplasmosis	Terminal ileum and colon	Intermittent bloody diarrhea, abdominal pain, fever, weight loss	EIA for urine or serum antigen. Histopathological examination using GMS stain	Itraconazole for patients with CD4 counts < 150/mm3	IV liposomal amphotericin B (3 mg/kg daily) for ≥ 2 weeks or clinical improvement with stepdown to oral itraconazole
Mycobacterium tuberculosis	Terminal ileum and cecum	Abdominal pain, diarrhea, fever, weight loss, night sweats, fatigue	Acid-fast staining	None recommended	Initial phase (2 months): Isoniazid 300 mg daily, rifampin 600 mg daily, pyrazinamide 25 mg/kg daily, and ethambutol 15 mg/kg daily. Continuation phase (4-7 months): Isoniazid 300 mg daily and rifampin 600 mg daily
Mycobacterium avium complex	Small bowel and large bowel	Fever, abdominal pain, weight loss, night sweats, fatigue	Acid-fast staining	Azithromycin for patients with CD4 count < 50/mm3	Clarithromycin (7.5 to 15 mg/kg PO BID for at least 12 months)

PCR: Polymerase chain reaction; PO: Per Os (by mouth/orally); BID: Bis in die (twice daily); QID: Quater in die (four times daily); TMP-SMX: Trimethoprim-Sulfamethoxazole; GMS: Grocott's methenamine Silver; EIA: Enzyme immunoassay.