Evaluation of Gentamicin Exposure Effects on Human gut Microbiota using the Simulator of Human Intestinal Microbial Ecosystem (SHIME)

Background: Antibiotics are emerging toxic contaminant that have potential public health risk worldwide. They may cause the human intestinal microbial disorder, as well as the spreading of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Most of the intestinal bacteria are not cultivable for the moment, tracking the special gene-labeled plasmid from the exogenous bacteria would help obtain the direct evidence of the horizontal transfer of ARGs in the intestinal flora. However, to date, there are only a few research reports applying the exogenous labeled bacteria to study the transfer of ARGs among intestinal bacteria. Therefore, for the first time, this study evaluated the in vitro ability of gentamicin on colonization of exogenous bacteria and plasmid in the simulated human gut. Results: This study indicated that exposure to gentamicin may be conducive to the colonization of exogenous bacteria and plasmid, as well as the conjugation of plasmid to gut microbiota. Gentamicin exposure was also confirmed to reduce the gene numbers of human disease-related pathways and promote the drug resistance in the gut microbiota. The effects on the genetic level might attribute to microbiota shift, as co-occurrence patterns suggested that Bacteroides attributed to the ARGs enrichment and Klebsiella played a crucial role in human disease-related pathways reduction after gentamicin treatment. Conclusion: These results may open up new perspectives for assessing the direct effects of antibiotics on the intestinal microbiota. These suggested side-effects should be considered for antibiotics prescription.