Impact of Pre-Operative Occult Bacteremia on Post-Operative Infectious Complications in Patients Undergoing Esophagectomy for Esophageal Cancer

<b><i>Purpose:</i></b> Occult bacteremia (OB), defined as blood stream micro-organisms confirmed by reverse transcriptase-quantitative polymerase chain reaction that target 16S or 23S ribosomal RNA, has been shown to increase the incidence of post-operative infections during pancreaticoduodenectomy. However, its impact on other surgical procedures remains unclear. This study aimed to evaluate the effect of pre-operative OB on post-operative surgical site infection (SSI) during esophageal cancer surgery. <b><i>Methods:</i></b> In this prospective observational study, 56 patients scheduled for esophagectomy were included. Pre-operative blood samples were tested for OB, and fecal samples were analyzed for microbiota. <b><i>Results:</i></b> Ten patients (18%) exhibited pre-operative OB. These patients had more frequent SSIs than did those without OB (40% vs. 10.9%, p = 0.044). Other complications or clinical factors did not substantially differ between the OB-positive and OB-negative groups. Fecal samples from OB-positive patients presented a greater prevalence of <i>Atopobium</i> clusters. In addition, the same bacterial species were detected in both the blood and feces of five OB-positive patients, with <i>Collinsella aerofaciens</i> being the most commonly shared species among <i>Atopobium</i> clusters. <b><i>Conclusions:</i></b> Pre-operative OB increased the risk of SSI following esophagectomy. These findings emphasize the potential role of the gut microbiota, particularly <i>Collinsella aerofaciens</i>, in OB and subsequent infections.