Acquisition of Multidrug-resistant Organisms in the Absence of Antimicrobials.

A nested case-control study among 137 nursing home residents who did not receive antimicrobials, of whom 44 acquired a multidrug-resistant organism, was performed. Risk factors for acquisition included gastrointestinal medications that affect the gut microbiome, number of visits from healthcare workers, pressure ulcers, and not residing in a dementia unit.