IDDF2018-ABS-0255 Impact of commensal human gut microbiota in the emergence of extensive drug-resistant pathogens

Abstract

Background Antimicrobial resistance (AMR) in human health associated bacterial pathogens is a serious concern across the globe. Human gastrointestinal tract (GIT) is populated with trillions of microbial species that contribute to nutrient assimilation, host and microbial cell signalling, pathogenesis and antimicrobial resistance (AMR). Indiscriminate usages of antimicrobial in healthcare, livestock, and agriculture provide an evolutionary advantage to the resistant variants. The ascendency of resistant variants threatens the efficacy of most, if not all, of the antimicrobial drugs commonly used to prevent or cure microbial infections. The aim of this current study was to understand the impact of commensal gut microbiota in the emergence of extensively drug-resistant (XDR) enteric pathogens. Methods Commensal anaerobic gut microbiota was isolated from the healthy Indians without a history of hospitalisation and antibiotic intake in last one year. AMR phenotypes were characterised in an anaerobic workstation using commercially avail Epsilometer test (E-test) strip. Genome of all the isolates was sequenced in GS-FLX +pyrosequencer. Genome assembly was done in GS de novo assembler. Genome annotation and analysis of resistance genes were done using Rapid Annotations using Subsystems Technology (RAST) platform. Results AMR traits in enteric bacteria, both in commensals and pathogens, are physically linked with mobile genetic elements (MGEs) and could rapidly disseminate to the bacterial species through horizontal gene transfer (HGT). Among commensal gut microbiota, the highest number of resistance phenotypes (n=12) and AMR encoding functions were detected in Faecalibacterium prausnitzii. Among pathogens, Vibrio cholerae and Klebsiella pneumoniae showed maximum resistance phenotypes (n=22). Genes encoding antibiotic resistance in commensal and pathogenic bacteria are physically linked with MGEs and could disseminate vertically to the progeny and laterally to the distantly related microbial species. Conclusions XDR pathogenic and commensal enteric bacteria are isolated from healthy Indian subjects without a significant history of hospitalisation or antibiotic consumption. Consequently, the transmissible AMR genes present in the genome of gut commensals could be a potential source of resistance functions for the enteric pathogens.