evolution of ciprofloxacin resistance in commensals and derived mutation population dynamics in natural populations.

Commensal are members of a healthy human oropharyngeal microbiome; however, they also serve as a reservoir of antimicrobial resistance for their pathogenic relatives. Despite their known importance as sources of novel genetic variation for pathogens, we still do not understand the full suite of resistance mutations commensal species can harbor. Here, we use selection to assess the mutations that emerge in response to ciprofloxacin selection in commensal by passaging 4 replicates of 4 different species in the presence of a selective antibiotic gradient for 20 days; then categorized derived mutations with whole genome sequencing.