Antibiotic resistome in a large-scale healthy human gut microbiota deciphered by metagenomic and network analyses

The human gut microbiota is an important reservoir of antibiotic resistance genes (ARGs). A metagenomic approach and network analysis were used to establish a comprehensive antibiotic resistome catalog and to obtain co-occurrence patterns between ARGs and microbial taxa in fecal samples from 180 healthy individuals from 11 different countries. In total, 507 ARG subtypes belonging to 20 ARG types were detected with abundances ranging from 7.12 x 10(-7) to 2.72 x 10(-1) copy of ARG/copy of 16S-rRNA gene. Tetracycline, multidrug, macrolide-lincosamide-streptogramin, bacitracin, vancomycin, beta-lactam and aminoglycoside resistance genes were the top seven most abundant ARG types. The multidrug ABC transporter, aadE, bacA, acrB, tetM, tetW, vanR and vanS were shared by all 180 individuals, suggesting their common occurrence in the human gut. Compared to populations from the other 10 countries, the Chinese population harboured the most abundant ARGs. Moreover, LEfSe analysis suggested that the MLS resistance type and its subtype 'ermF' were representative ARGs of the Chinese population. Antibiotic inactivation, antibiotic target alteration and antibiotic efflux were the dominant resistance mechanism categories in all populations. Procrustes analysis revealed that microbial phylogeny structured the antibiotic resistome. Co-occurrence patterns obtained via network analysis implied that 12 species might be potential hosts of 58 ARG subtypes.