Refractory Clostridium difficile Infection and Simultaneous Cytomegalovirus Activation in a Post-Kidney Transplant Patient: Diagnostic Challenge and Utility of Fecal Microbiota Transplantation

Introduction: Infections are major complications in post-kidney transplant patients due to intense immunosuppression, with C. difficile infection (CDI) and Cytomegalovirus (CMV) posing diagnostic challenges due to overlapping symptoms. Fecal Microbiota Transplantation (FMT) is effective for refractory CDI, with limited data on its use for CMV. Few cases of co-infection with CMV and C. difficile have been reported previously. Case Description: A 58-year-old male, who received a related living donor kidney transplant in 2023, presented to the ER with refractory diarrhea, fever, and abdominal pain. He was considered at intermediate risk for CMV (both recipient and donor were CMV IgG positive) and had received basiliximab induction therapy followed by maintenance Mycophenolic acid and Tacrolimus, with documented adequate therapeutic serum levels. Initial colonoscopy biopsy was CMV-negative by PCR/IHC, but stool was CDI-positive based on the detection of both GDH and A/B toxins. Despite oral vancomycin and IV metronidazole, symptoms persisted. Repeat colonoscopy showed CMV colitis by IHC (PCR negative) and IV ganciclovir was initiated. By day 9 of hospitalization, the patient showed partial improvement with the established management; however, he persisted with 4-5 diarrheal stools a day, accompanied by intermittent abdominal pain. Due to this, it was decided to perform a FMT, for both refractory CDI and CMV colitis, which was carried out successfully with adequate response. Discussion: This case highlights the complex management of opportunistic infections in post-renal transplant patients, even with therapeutic range immunosuppressant levels and no graft rejection. Co-infection of CDI and CMV is rare but there are a few cases reported in literature, with CDI potentially predisposing to CMV reactivation, in our opinion, our case is compatible with the latter. Recent evidence suggests FMT utility in CMV colitis, mainly in pediatric IBD. Our case demonstrates successful FMT for refractory CDI and concurrent CMV colitis in a kidney transplant recipient, adding to the scarce evidence in this population.