Project description:The diverse bacterial communities that colonize the gastrointestinal tract play an essential role in maintaining immune homeostasis through the production of critical metabolites such as short chain fatty acids (SCFA), and this can be disrupted by antibiotic use. However, few studies have addressed the effects of specific antibiotics longitudinally on the microbiome and immunity. We evaluated the effects of four specific antibiotics; enrofloxacin, cephalexin, paromomycin, and clindamycin; in healthy female rhesus macaques. All antibiotics disrupted the microbiome, including reduced abundances of fermentative bacteria and increased abundances of potentially pathogenic bacteria, including Enterobacteriaceae in stool, and decreased Helicobacteraceae in the colon. This was associated with decreased SCFAs, indicating altered bacterial metabolism. Importantly, antibiotic use also substantially altered local immune responses, including increased neutrophils and Th17 cells in the colon. Furthermore, we observed increased soluble-CD14 in plasma, indicating microbial translocation. These data provide a longitudinal evaluation of antibiotic-induced changes to the composition and function of colonic bacterial communities, associated with specific alterations in mucosal and systemic immunity.
Project description:Fluoroquinolone antibiotics, a common antibiotic for the treatment of Pseudomonas aeruginosa infection, are facing challenges due to the rapid evolution of bacterial resistance. Through designed evolutionary experiments in vitro, we find that there are significant differences in evolutionary trajectories and outcomes of resistant bacteria obtained in different induction modes, among which fitness benefit of resistant strains obtained in high-dose induction mode under high level of antibiotic is significantly higher than that of wild-type strain, and collateral sensitivity to aminoglycosides and some other antibiotics will be obtained. Resistance strains obtained in the low-dose induction mode exhibit higher heterogeneity, which is accompanied by multiple drug resistance (MDR). Through second generation resequencing and proteomic techniques, overexpression of MexCD-OprJ efflux pump induced by mutations in the nfxB gene significantly improved the fitness benefit of Pseudomonas aeruginosa PAO1 under high level of fluoroquinolones. This is the precondition of the further evolution of the fleroxacin-resistant strains in the high dose induction mode, the addition of the efflux pump inhibitor phenylalanyl arginyl β-naphthylamide (PAβN) could effectively repress the evolution of bacterial resistance in the high dose induction mode. Fleroxacin use followed by gentamicin helped drive infectious P.aeruginosa to extinction, causing nfxB mutation to cause collateral sensitivity to gentamicin.