Document resource
Background The profound impact of the microbiota on health and diseases such as cancer, is increasingly apparent, with emerging evidence highlighting a distinct tumor microbiome in extra-intestinal sites. The presence of certain intratumoral bacteria seem to have a functional role in tumor progression of various cancers. However, the origin of these tumor-colonizing microbes remains a key question.Methods This study demonstrates that gut commensal bacteria inherently translocate systemically to populate multiple sites such as tumors and systemic organs. Using culture-based approaches and in vivo bacterial translocation studies, we show that orally administered E. coli or L. reuteri rapidly translocate to systemic sites, including tumors.Results Bacterial translocation is independent of host genetic background, sex of the host, or existing gut microbiota composition. Moreover, varying compositions of fecal microbial transplants differentially impacted the tissue and tumor microbiome at gut-distal sites.Conclusions These findings reveal that inherent commensal translocation shapes extra-intestinal tumor and tissue microbiomes, offering potential avenues for targeted gut-distal microbiome modulation.