Deciphering the Post-Operative Dynamics of Opportunistic Gut Microbiota in Colorectal Cancer Patients

Recent studies indicate that opportunistic gut bacteria contribute to the recurrence and chemoresistance in colorectal cancer (CRC); however, their fate after surgical resection remains poorly understood. This study investigated the longitudinal changes in these bacteria and assessed their potential persistence following CRC surgery. Forty fecal samples were collected from ten CRC patients at four timepoints: (1) pre-surgery (S); (2) one week (S1); (3) one month (S2); and (4) three months (S3) post-surgery. Fifteen other fecal samples were collected from healthy individuals as our study controls. Microbial profiling was performed using 16S rRNA gene sequencing, and quantitative PCR was applied to assess the changes in three opportunistic bacteria associated with CRC-associated. Our study revealed that Escherichia coli was significantly enriched in pre-surgical samples (S), while Enterococcus faecalis was predominant in the samples collected one-week after surgery (S1). All the assessed species showed a gradual post-surgical decline in relative abundance, suggesting they do not persist after resection. Additionally, there was a significant increase in relative abundance of beneficial bacterial signatures, including Akkermansia muciniphila, Bacteroides uniformis, Parabacteroides merdae, and Phascolarctobacterium faecium post-surgery, which implies a potential dysbiosis restoration. Our findings suggest that surgical resection gradually reduces the burden of opportunistic gut microbiota, thus gradually lowering the risk of recurrence and chemoresistance. Additionally, it may facilitate the restoration of beneficial taxa. Future studies should include extended follow-up periods to validate our findings and their correlation with clinical outcomes.