Effects of four antibiotics on the diversity of the intestinal microbiota

Oral antibiotics remain the therapy of choice for severe bacterial infections; however, antibiotic use disrupts the intestinal microbiota, which increases the risk of colonization with intestinal pathogens. Currently, our understanding of antibiotic-mediated disturbances of the microbiota remains at the level of bacterial families or specific species, and little is known about the effect of antibiotics on potentially beneficial and potentially pathogenic bacteria under conditions of gut microbiota dysbiosis. Additionally, it is controversial whether the effects of antibiotics on the gut microbiota are temporary or permanent. In this study, we used 16S rRNA gene sequencing to evaluate the short-term and long-term effects of ampicillin, vancomycin, metronidazole, and neomycin on the murine intestinal microbiota by analyzing changes in the relative numbers of potentially beneficial and potentially pathogenic bacteria. We found that the changes in the intestinal microbiota reflected the antibiotics mechanisms of action and that dysbiosis of the intestinal microbiota led to competition between the different bacterial communities. Thus, destruction of bacteria with beneficial potential increased the abundance of bacteria with pathogenic potential. In addition, we found that these oral antibiotics had long-term negative effects on the intestinal microbiota and promoted the development of antibiotic-resistant bacterial strains. These results indicate that ampicillin, vancomycin, metronidazole, and neomycin have long-term negative effects and can cause irreversible changes in the diversity of the intestinal microbiota and the relative proportions of bacteria with beneficial potential and bacteria with pathogenic potential, thereby increasing the risk of host disease.