Case Presentation: A 46-year-old female with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) on antiretroviral therapy, as well as stage IV diffuse large B-cell lymphoma with central nervous system involvement presented to clinic two weeks after her last chemotherapy session where she was found to have a fever to 101 degrees Fahrenheit and an absolute neutrophil count (ANC) of 900, but was otherwise asymptomatic. She was admitted to the hospital for neutropenic fever and started on broad-spectrum antibiotics. Her initial infectious workup remained negative. On hospital day (HD) 3, the patient developed diarrhea and was found to have Clostridium difficile colitis. CT imaging of her abdomen and pelvis was also notable for typhlitis and a perianal abscess. These infections slowly resolved with appropriate antimicrobial treatment, confirmed by repeat CT imaging and repeat stool C. difficile polymerase chain reaction (PCR). Nevertheless, the patient continued to have fever and copious diarrhea requiring continuous IV fluid replacement. On HD 18, the patient underwent colonoscopy, with biopsy revealing colitis secondary to both Cytomegalovirus (CMV) and Cryptosporidium co-infection. The patient was started on IV ganciclovir and oral paromomycin with rapid resolution of symptoms.
Discussion: This is a case of severe diarrhea secondary to co-infection with C. difficile colitis, CMV colitis, and cryptosporidiosis in an immunocompromised patient. This may be the first reported case of diarrhea secondary to triple infection with these three specific organisms. This case highlights the importance of considering a broad differential diagnosis for diarrhea in immunocompromised patients, which should include both infectious and noninfectious etiologies. Data regarding rates for diarrheal co-infection are sparse; however, the rate was estimated at 22% among adult immunocompromised inpatients in one 1988 article. It is not fully understood why patients with AIDS are susceptible to diarrheal co-infections; however, experts postulate that HIV-induced architectural changes to the GI tract, profound immunosuppression, and the presence of latent infections with pathogens that are prone to reactivation (such as CMV) are all likely contributing factors.
Conclusions: Diarrheal illness in the immunosuppressed patient represents a diagnostic quandary as there are multiple possible causes, both infectious and non-infectious. Diagnostic work up should begin with C. difficile PCR, stool cultures and ova and parasite exams. For severe persistent symptoms despite appropriate treatment for known causes, clinicians should consider the possibility of co-infection with multiple organisms. In these cases, more invasive diagnostic modalities, such as colonoscopy with biopsy, may be indicated.