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

Preoperative gut microbiota showed similar alpha-diversity indices and community structures between infected and non-infected heart transplant patients.

• Twenty patients undergoing allogeneic heart transplantation were enrolled.
• Gut microbiota profiles were analyzed via 16S rRNA gene sequencing at 5-9 days preoperatively.
• Alpha and beta diversity metrics did not significantly differ between Pre-NI and Pre-I groups preoperatively.
• Community structure similarity was observed across preoperative groups prior to surgical intervention.

Preoperative non-infected (Pre-NI) gut microbiota were dominated by Bacteroides, while preoperative infected (Pre-I) samples were enriched with Enterococcus casseliflavus, Limosilactobacillus, and Weissella cibaria.

• Bacteroides was the dominant genus in Pre-NI patients.
• Pre-I patients showed enrichment of Enterococcus casseliflavus, Limosilactobacillus, and Weissella cibaria.
• These compositional differences were identified through 16S rRNA gene sequencing and MaAsLin analysis.
• The Bacteroides-Enterococcus-Limosilactobacillus axis showed dynamic preoperative shifts associated with infection status.

Postoperative non-infected (Post-NI) patients showed higher microbial diversity and Blautia enrichment compared to postoperative infected (Post-I) patients.

• Post-NI patients demonstrated higher Shannon and Simpson diversity indices at 30 days postoperatively.
• Blautia, a butyrate-producing genus, was enriched in Post-NI patients.
• Post-I patients formed a distinct cluster with Enterococcus faecium dominance.
• Metabolic analysis highlighted Blautia-associated pathways, including L-1,2-propanediol degradation.

Postoperative infected patients were characterized by Enterococcus faecium dominance and formed a distinct microbial community cluster.

• Beta diversity analysis revealed that Post-I patients clustered separately from Post-NI patients at 30 days postoperatively.
• Enterococcus faecium was the dominant taxon in Post-I patients.
• This pattern was associated with antibiotic exposure and immunosuppressant use following transplantation.
• Postoperative shifts toward Blautia-Enterococcus dominance were linked to infection status.

Metabolic pathway prediction identified Blautia-associated pathways, particularly L-1,2-propanediol degradation, as differentially represented between postoperative groups.

• Functional analysis was performed using PICRUSt2 for metabolic pathway prediction.
• L-1,2-propanediol degradation was among the highlighted Blautia-associated metabolic pathways.
• These metabolic differences corresponded to enrichment of butyrate-producing microbiota in non-infected postoperative patients.
• The findings support a functional role for Blautia in the metabolic environment of non-infected transplant patients.

Dual-target intervention emphasizing restoration of butyrate-producing microbiota and monitoring of Enterococcus dynamics is recommended for personalized infection control in transplant patients.

• The recommendation is based on observed associations between Blautia (butyrate-producer) enrichment and non-infected status postoperatively.
• Enterococcus dynamics were identified as a key indicator of infection risk both pre- and postoperatively.
• The study cohort consisted of 20 allogeneic heart transplant patients analyzed at two time points.
• Antibiotic and immunosuppressant exposure were identified as factors impacting the Bacteroides-Enterococcus-Limosilactobacillus and Blautia-Enterococcus axes.