Gut microbiota and metabolic pathway profiles in infected and non-infected heart transplant patients before and after surgery

The composition and metabolic characteristics of gut microbiota in heart transplant patients with and without preoperative and postoperative infection were investigated to elucidate the impact of antibiotics and immunosuppressants. Twenty patients undergoing allogeneic heart transplantation were enrolled. Gut microbiota profiles were analyzed via 16 S rRNA gene sequencing and metabolic pathway prediction (PICRUSt2) at 5-9 days preoperatively and 30 days postoperatively. Patients were categorized into preoperative non-infected (Pre-NI), preoperative infected (Pre-I), postoperative non-infected (Post-NI) and postoperative infected (Post-I) groups for comparative analysis. Alpha/beta diversity, Maaslin and functional analyses were performed. Preoperative microbiota had similar α-diversity indices and community structures among groups. Pre-NI microbiota were dominated by Bacteroides and Pre-I samples were enriched with Enterococcus casseliflavus、Limosilactobacillus and Weissella cibaria. Post-NI patients showed higher microbial diversity (Shannon/Simpson indices) and Blautia (butyrate-producer) whereas Post-I patients formed a distinct cluster with Enterococcus faecium dominance. Metabolic analysis highlighted Blautia-associated pathways, e.g., L-1,2-propanediol degradation. Dynamic preoperative shifts in the Bacteroides-Enterococcus-Limosilactobacillus axis and postoperative shifts toward Blautia-Enterococcus dominance were found in heart transplant patients and were associated with infection status and antibiotic exposure. Dual-target intervention with an emphasis on restoring butyrate-producing microbiota and monitoring Enterococcus dynamics is recommended to optimize personalized infection control systems in transplant patients.