What is the approach to diarrhea in HIV infected patients?
It is important to consider patient exposures. A history of new medications or an alteration in a current regimen, such as antiretrovirals or antibacterials, is important because many protease inhibitors are associated with diarrhea and antibacterials are associated with Clostridium difficile colitis. In febrile patients, blood cultures should be obtained for common bacteria such as are mandatory. If stool and blood culture studies are negative, the next step is endoscopic evaluation with biopsy. In the presence of colitis symptoms, flexible sigmoidoscopy or colonoscopy is recommended.
The below table summarizes the studies and laboratory tests used in the evaluation of diarrhea in AIDS.
Studies and Laboratory Tests Used in the Evaluation of Diarrhea in AIDS
|Stool||Cultures (Salmonella, Shigella, Campylobacter spp.)|
Toxin ( Clostridium difficile )
Ova and parasites ( Giardia lamblia, Entamoeba histolytica, Cryptosporidium spp.)
Modified Kinyoun acid-fast ( Cryptosporidium spp., Isospora belli )
Concentrated stool (zinc sulfate, Sheather sucrose flotation) (microsporidia)
|Blood||Cultures ( Mycobacterium avium complex, Salmonella, Campylobacter spp.)|
Antibodies ( Entamoeba histolytica, CMV)
|Gastrointestinal fluids||Duodenal aspirate ( Giardia lamblia, microsporidia)|
Electron microscopy ( Cryptosporidium spp., adenovirus)
Gyms or methenamine silver (fungi)
Methylene blue–azure II–basic fuchsin (microsporidia)
|Immunohistochemical stains (CMV), immunologic methods||In situ hybridization (CMV)|
DNA amplification (CMV)
Culture of tissue
Herpes simplex virus
AIDS, Acquired immune deficiency syndrome; CMV, cytomegalovirus.
lists the most common infectious causes of diarrhea in AIDS.
The below table lists common associations between exposures and infections.
Infectious Causes of Diarrhea in AIDS
Small round virus
Mycobacterium avium complex
Pseudomonas spp. (?)
Encephalitozoon intestinalis (formerly Septata )
Blastocystis hominis (?)
AIDS, Acquired immune deficiency syndrome; HIV, human immunodeficiency virus.
Sources of Infectious Diarrhea
|Clostridium difficile||Recent antibiotics, nursing home or hospital exposures|
|Recent visit to a farm, contact with farm animals, use of a public swimming pool|
|Giardia||Camping, stream water|
|Mycobacterium avium||CD4 count less than 50|
|Cyclospora cayetanensis||Common cause of diarrhea in South America|
|Microsporidiosis||Uncommon in the southern United States|
|Rotavirus||Common cause of diarrhea in Australia|