Antimicrobial treatment impacts resistance in off-target populations of a nosocomial bacterial pathogen: a case-control study.

The antimicrobial resistance crisis has persisted despite broad attempts at intervention. Detailed studies of the population dynamics that lead to resistance could identify additional intervention points. An important driver of resistance in the most concerning antibiotic resistant pathogens can be selection imposed on bacterial populations that are not the intended target of antimicrobial therapy. Here we focus on the important nosocomial pathogen Enterococcus faecium in a hospital system where resistance to daptomycin is evolving despite standard interventions.