New Acquisition of Antibiotic-Resistant Organisms in Skilled Nursing Facilities

The epidemiology of new acquisition of antibiotic-resistant organisms (AROs) in community-based skilled nursing facilities (SNFs) is not well studied. To define the incidence, persistence of, and time to new colonization with methicillin-resistant Staph-ylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and ceftazidime-resistant (CAZr) and ciprofloxacin-resistant (CIPr) Gram-negative bacteria (GNB) in SNFs, SNF residents were enrolled and specimens from the nares, oropharynx, groin, perianal area, and wounds were prospectively cultured monthly. Standard microbiological tests were used to identify MRSA, VRE, and CAZr and CIPr GNB. Residents with at least 3 months of follow-up were included in the analysis. Colonized residents were categorized as having either preexisting or new acquisition. The time to colonization for new acquisition of AROs was cal-culated. Eighty-two residents met the eligibility criteria. New acquisition of AROs was common. For example, of the 59 residents colonized with CIPr GNB, 28 (47%) were colonized with CIPr GNB at the start of the study (96 % persistent and 4 % intermittent), and 31 (53%) acquired CIPr GNB at the facility (61 % persistent). The time to new acquisition was shortest for CIPr GNB, at a mean of 75.5 days; the time to new acquisition for MRSA was 126.6 days (P 0.007 versus CIPr GNB), that for CAZr was 176.0 days (P 0.0001 versus CIPr GNB), and that for VRE was 186.0 days (P 0.0004 versus CIPr GNB). Functional status was signif-icantly associated with new acquisition of AROs (odds ratio [OR], 1.24; P 0.01). New acquisition of AROs, in particular CIPr GNB andMRSA, is common in SNFs. CIPr GNB are acquired rapidly. Additional longitudinal studies to investigate risk factors for ARO acquisition are required