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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 (SCFAs) 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 the 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.

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.