title: Prevalence of and risk factors for multidrug-resistant Acinetobacter baumannii colonization among high-risk nursing home residents.
abstract: OBJECTIVE
  To characterize the epidemiology of multidrug-resistant (MDR) Acinetobacter baumannii colonization in high-risk nursing home (NH) residents.
  
  
  METHODS
  Nested case-control study within a multicenter prospective intervention trial.
  
  
  METHODS
  Four NHs in Southeast Michigan. PARTICIPANTS Case 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 MDR A. baumannii.
  
  
  METHODS
  For 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. baumannii strains and their susceptibilities were identified using standard microbiologic methods.
  
  
  RESULTS
  Of 168 NH residents, 25 (15%) were colonized with MDR A. 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 with Proteus 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.
  
  
  CONCLUSIONS
  Functional disability, P. mirabilis colonization, and diabetes mellitus are important risk factors for colonization with MDR A. baumannii in high-risk NH residents. A. baumannii exhibits widespread antibiotic resistance and a preference to colonize with other antibiotic-resistant organisms, meriting enhanced attention and improved infection control practices in these residents.
authors.affiliation: 1Division of Geriatric and Palliative Care Medicine,University of Michigan Medical School,Ann Arbor,Michigan.
authors.forename: Lona
authors.initials: L
authors.lastname: Mody
authors.affiliation: 1Division of Geriatric and Palliative Care Medicine,University of Michigan Medical School,Ann Arbor,Michigan.
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Gibson
authors.affiliation: 3Department of Epidemiology,School of Public Health,University of Michigan,Ann Arbor,Michigan.
authors.forename: Amanda
authors.initials: A
authors.lastname: Horcher
authors.affiliation: 4Veterans Affairs Center for Clinical Management Research,Ann Arbor,Michigan.
authors.forename: Katherine
authors.initials: K
authors.lastname: Prenovost
authors.affiliation: 1Division of Geriatric and Palliative Care Medicine,University of Michigan Medical School,Ann Arbor,Michigan.
authors.forename: Sara E
authors.initials: SE
authors.lastname: McNamara
authors.affiliation: 3Department of Epidemiology,School of Public Health,University of Michigan,Ann Arbor,Michigan.
authors.forename: Betsy
authors.initials: B
authors.lastname: Foxman
authors.affiliation: 5Division of Infectious Diseases,Detroit Medical Center and Wayne State University,Detroit,Michigan.
authors.forename: Keith S
authors.initials: KS
authors.lastname: Kaye
authors.affiliation: 6Infectious Diseases Section,Veterans Affairs Ann Arbor Healthcare System and the University of Michigan Medical School,Ann Arbor,Michigan.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Bradley
mesh_terms: D000151:Acinetobacter Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D040981:Acinetobacter baumannii / Q000302:isolation & purification; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006707:Homes for the Aged; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009735:Nursing Homes; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors