Dietary intake of enrofloxacin promotes the spread of antibiotic resistance from food to simulated human gut

Antibiotic residues are commonly found in food. The effect of dietary exposure to veterinary antibiotics on the transmission of antibiotic-resistant bacteria and antibiotic resistance genes (ARGs) from food to humans is unknown. We found that dietary exposure to enrofloxacin reduced microbial diversity, interactions, and the immune responses; weakened the colonization resistance of the resident microbiota; and promoted the colonization of exogenous Escherichia coli K-12 MG1655 in the simulated human intestine both in vitro and in vivo experiments in mice. In addition to the growth advantages for potential most likely bacterial hosts of ARGs under enrofloxacin exposure, the dietary exposure to enrofloxacin promoted horizontal transfer of resistance plasmids and altered the simulated human gut antibiotic resistome in a time-dependent manner. Collectively, these findings demonstrated that dietary intake of enrofloxacin promoted the colonization of E. coli K-12 MG1655 in the simulated human intestine and the horizontal transfer of ARGs, highlighting the risk of antibiotic resistance transmission from food to humans mediated by dietary exposure to veterinary antibiotics.