Fecal Microbiota Transplantation for Intractable Diarrhea due to Severe Dysbiosis and Cytomegalovirus Enteritis: A Case Report

Background: Cytomegalovirus (CMV) enteritis can lead to intractable diarrhea, especially when complicated by severe gut dysbiosis, posing a significant therapeutic challenge. Methods: We present a case of a 40-year-old woman with a history of traumatic brain injury and prolonged broad-spectrum antibiotic use, who developed persistent bloody, mucus-containing diarrhea (up to 40 episodes daily). Colonoscopy with biopsy confirmed CMV enteritis, and 16S rRNA sequencing revealed severe intestinal dysbiosis. Treatment consisted of intravenous ganciclovir combined with multiple sessions of fecal microbiota transplantation (FMT) delivered via jejunal tube, alongside tailored nutritional support. Results: Despite initial persistence of symptoms, the combined antiviral and FMT regimen led to resolution of diarrhea, normalization of inflammatory markers, and restoration of enteral tolerance. Follow-up colonoscopy showed mucosal healing and negative CMV staining. Microbiota analysis demonstrated restoration of diversity and a shift toward donor-like taxonomic profiles. Conclusions: This case highlights CMV as an emerging cause of severe enteritis in non-immunosuppressed surgical patients and supports the efficacy of combined antiviral therapy and FMT for refractory diarrhea associated with dysbiosis and CMV infection.