A 46-year-old woman with newly diagnosed and untreated HIV infection was admitted to the ICU last night with possible pneumocystis pneumonia. Her CD4 count is 42 cells/µL. She is currently intubated and sedated. Since arrival she has had five episodes of bloody loose stools. PCR for C. difficile is negative and stool studies for bacteria and parasites are pending. Colonoscopy performed at bedside reveals areas of friable, erythematous mucosa with submucosal hemorrhage and large, deep ulcerations. Biopsies are sent for definitive diagnosis.
What empiric antimicrobial should you start while awaiting results?
A. CiprofloxacinCorrect Answer: C
Although increasingly rare with improvements in antiretroviral therapy, cytomegalovirus colitis is still a concern in HIV-positive patients with CD4 counts <100 cells/µL (usually <50 cells/µL). As the colitis progresses through the full thickness of the bowel, there is a risk for perforation, a life-threatening surgical emergency. Other complications include hemorrhage, infection, and toxic megacolon. Thinning of the bowel wall can lead to bacteremia. Patients with suspected CMV colitis with severe symptoms such as this one should be started on empiric antiviral therapy while awaiting definitive pathologic diagnosis. Endoscopic and biopsy findings confirm the diagnosis. Endoscopy findings are variable and can include diffuse or localized areas of friable, erythematous mucosa with submucosal hemorrhage and mucosal ulcerations. Biopsy shows characteristic intranuclear (“owl’s eye”) and cytoplasmic inclusion bodies. Recommended treatment is either ganciclovir or foscarnet for 3 to 6 weeks. Relapse is common and maintenance therapy is often required for those with poorly controlled HIV. Prophylaxis with valganciclovir is indicated until the CD4 count is >100 cells/µL for 6 months, and there is no evidence of active CMV disease. PCR for toxigenic genes is highly specific and sensitive for diagnosis of C. difficile colitis. So, a negative PCR rules out CDI.
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