Brief antibiotic use drives human gut bacteria towards low-cost resistance

A study involving 60 human participants exposed to ciprofloxacin found that brief exposure drives the evolution of antimicrobial resistance in gut commensals. The study found that gyrase mutations arose de novo within the participants and exhibited no measurable fitness cost. The findings highlight the human gut’s capacity to promote resistance evolution and identify key genomic and ecological factors that shape bacterial adaptation in vivo. This research underscores the importance of understanding the relationship between antibiotic use and antimicrobial resistance.