Prevalence of and Risk Factors for Multidrug-ResistantAcinetobacter baumanniiColonization Among High-Risk Nursing Home Residents

Abstract

OBJECTIVETo characterize the epidemiology of multidrug-resistant (MDR)Acinetobacter baumanniicolonization in high-risk nursing home (NH) residents.DESIGNNested case-control study within a multicenter prospective intervention trial.SETTINGFour NHs in Southeast Michigan.PARTICIPANTSCase patients and control subjects were NH residents with an indwelling device (urinary catheter and/or feeding tube) selected from the control arm of the Targeted Infection Prevention study. Cases were residents colonized with MDR (resistant to ≥3 classes of antibiotics)A. baumannii; controls were never colonized with MDRA. baumannii.METHODSFor active surveillance cultures, specimens from the nares, oropharynx, groin, perianal area, wounds, and device insertion site(s) were collected upon study enrollment, day 14, and monthly thereafter.A. baumanniistrains and their susceptibilities were identified using standard microbiologic methods.RESULTSOf 168 NH residents, 25 (15%) were colonized with MDRA. baumannii. Compared with the 143 controls, cases were more functionally disabled (Physical Self-Maintenance Score >24; odds ratio, 5.1 [95% CI, 1.8–14.9];P<.004), colonized withProteus mirabilis(5.8 [1.9–17.9];P<.003), and diabetic (3.4 [1.2–9.9];P<.03). Most cases (22 [88%]) were colonized with multiple antibiotic-resistant organisms and 16 (64%) exhibited co-colonization with at least one other resistant gram-negative bacteria.CONCLUSIONFunctional disability,P. mirabiliscolonization, and diabetes mellitus are important risk factors for colonization with MDRA. baumanniiin high-risk NH residents.A. baumanniiexhibits widespread antibiotic resistance and a preference to colonize with other antibiotic-resistant organisms, meriting enhanced attention and improved infection control practices in these residents.Infect Control Hosp Epidemiol 2015;36(10):1155–1162