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Physicians Must Recognize CMV in Patients With HIV/AIDS
Q: What Colonic Infections Are Associated With AIDS?
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A: Given the high-risk of infectious diarrhea in patients with human immunodeficiency virus, any patient with more than 1 week of diarrhea deserves appropriate workup. Diarrhea is defined as more than three bowel movements and more than 200 g of stool output per day. Especially in patients with abdominal pain, large volume diarrhea, hematochezia, or fevers and chills, an infectious process has to be strongly considered. Stool samples should be sent for fecal leukocytes, stool culture, fecal ova and parasites (x 3), Clostridium difficile (especially in patients currently or recently on antibiotics, those with recent hospitalizations, or in those living in institutional settings), and acid-fast stains. Patients who appear systemically ill should be hospitalized and blood cultures should be performed.
For AIDS patients with infectious diarrhea, a number of unusual culprit organisms need to be considered. Organisms like Mycobacterium avium, Cryptosporidium parvum, and microspiridiae species are unique pathogens seen in the immunocompromised (Figure 1). However, more common organisms like Clostridium difficile and Entamoeba histolytica also deserve strong consideration. Bloody diarrhea should raise concerns for Salmonella, Shigella, and Enterohemorrhagic E. Coli (EHEC). Stool cultures and studies, to include assays for microsporidium and acid-fast organisms, can be essential in defining the etiology.
Of the various infectious diseases that can infect the colon in the setting of AIDS, one important consideration is cytomegalovirus (CMV). CMV is still an uncommon disorder, but is important to recognize because of the potential for morbidity and mortality if not diagnosed early. Historically, CMV infection of the gastrointestinal tract was thought to occur in up to about 5% of patients with AIDS, but the incidence of this infection has decreased as the rate of AIDS among patients with HIV has diminished through HAART (highly active antiretroviral therapy). As the degree of viremia increases and the CD4 count decreases, the risk of CMV increases — as does the risk of other opportunistic infections of the intestinal tract. In addition to viremia and immunosuppression, the presence of CMV in the serum is the most important risk factor for gastrointestinal involvement. CMV colitis typically manifests with malaise, anorexia, weight loss, low-grade fevers, abdominal pain, and diarrhea. Diarrhea can be episodic, but can also be quite severe and associated with life-threatening hemorrhage. Rarely, patients present with colonic perforation, which is the most devastating complication. Diagnosis is typically based on clinical suspicion, but can also be made through demonstration of CMV viremia or through CMV antigen assays. It should be noted, however, that AIDS patients can be viremic in the absence of colonic involvement, and CMV viremia may not be detectable in the setting of active CMV colitis. During endoscopic evaluation, the colon can range in appearance from normal to frank necrotizing colitis. Biopsies of the mucosa typically show inflammation, vascular endothelial infiltration, and tissue necrosis, but examination with hematoxylin and eosin staining should reveal large cells with eosinophilic and basophilic intracytoplasmic inclusion bodies called cytomegalic cells. Initiation of HAART therapy helps avoid the dreaded complications of hemorrhage and perforation. Before HAART therapy, infection of the colon with CMV carried a grim prognosis with nearly half of the patients dying within 4 months of diagnosis. Finally, it is important to recognize that patients infected with CMV colitis can often have concomitant CMV retinitis, so they should undergo ophthalmological assessment to address this possibility.
Image: Mulhall B
Excerpted from:
Cash BD, Farraye FA, eds. Curbside Consultation of the Colon: 49 Clinical Questions, Second Edition (pp 51-53) ©2009 SLACK Incorporated.
- References:
- Cheung TW, Teich SA. Mt Sinai J Med. 1999; 66(2):113-124.
- Johanson JF. Can J Gastroenterol. 1996;10(7):461-468.
- Mönkemüller KE, Wilcox CM. Gastrointest Endosc Clin N Am. 1998;8(4):889-911.
- Thom K, Forrest G. Curr Opin Gastroenterol. 2006;22(1):18-23.
- For more information on the Curbside Consultation in Gastroenterology Series:
- See Healio.com/Books/Gastroenterology.