Fecal microbiota transplantation as a therapeutic modality for recurrent Clostridioides difficile infection: reviewing efficacy, safety, mechanisms of action, and outcomes.

Recurrent Clostridioides difficile infection (rCDI) remains a significant global health challenge, characterized by high morbidity, substantial healthcare costs, and an increased risk of severe complications. C. difficile, a gram-positive, spore-forming bacterium, is the primary cause of healthcare-associated diarrhea. The pathogenesis of rCDI is closely tied to gut microbiota disruptions, often triggered by antibiotic use, immunosuppression, and prolonged hospital stays. While effective for initial episodes, standard antibiotic therapies paradoxically exacerbate microbiota dysbiosis, increasing the risk of recurrence. Approximately 20%-30% of patients experience a recurrence after the initial episode, with rates rising to 45%-65% in those with multiple episodes. Fecal microbiota transplantation (FMT) has arrived as a transformative therapy for rCDI, leveraging donor microbiota to restore gut homeostasis and suppress C. difficile colonization. Clinical trials consistently report success rates exceeding 80%, markedly surpassing outcomes with antibiotics. Innovations in delivery methods, including oral capsules, have enhanced FMT's accessibility and patient acceptability. However, concerns surrounding safety and standardization persist. Adverse events, such as gastrointestinal discomfort and rare cases of multidrug-resistant organism transmission, underscore the need for stringent donor screening protocols. Emerging evidence reveals complex mechanisms underpinning FMT's efficacy, including restoring microbial diversity, bile acid metabolism, and short-chain fatty acid production. Long-term benefits, such as sustained microbiota stability, and potential applications in other conditions, including inflammatory bowel disease and metabolic disorders, are promising but require further validation. Addressing challenges in donor selection, regulatory oversight, and personalized approaches will be critical to optimizing FMT as a safe and effective therapeutic strategy for rCDI.