Prevalence of multidrug-resistant organisms and risk factors for carriage in long-term care facilities: a nested case-control study

J Antimicrob Chemother. 2014 Jul;69(7):1972-80. doi: 10.1093/jac/dku077. Epub 2014 Apr 7.

Abstract

Background: Long-term care facilities (LTCFs) are a potentially important reservoir of multidrug-resistant (MDR) organisms; however, limited data exist.

Methods: A point-prevalence study was conducted in four co-located LTCFs in Australia. Nasal and rectal swabs were cultured for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and MDR Gram-negative bacilli (GNB). Molecular typing and resistance detection were performed. Risk factors for colonization with an MDR organism were determined using a nested case-control study.

Results: Consent was obtained from 115 (85%) of 136 eligible participants. Forty-one (36%) residents carried at least one type of MDR organism. The prevalence was 16% MRSA (n = 18), 6% VRE (n = 7) and 21% MDR GNB [n = 24; including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (n = 12) and Acinetobacter baumannii (n = 6)]. The majority of ESBL-producing E. coli and A. baumannii were clonal. Current wound management [adjusted OR (AOR) 8.81 (95% CI 2.78-27.94), P < 0.001], medical device in situ [AOR 5.58 (95% CI 1.34-23.32), P = 0.018] and pressure ulcer [AOR 3.69 (95% CI 1.06-12.86), P = 0.04] were independent risk factors for MDR organism colonization. Advanced dementia [AOR 3.54 (95% CI 1.23-10.23), P = 0.02] and prolonged antibiotic use [AOR 2.95 (95% CI 1.01-8.60), P = 0.047] were independently associated with MRSA colonization, whilst current wound management [AOR 15.59 (95% CI 4.85-50.10), P < 0.001] and fluoroquinolone use [AOR 4.27 (95% CI 1.20-15.25), P = 0.025] were risk factors for MDR GNB colonization.

Conclusions: LTCFs are an important reservoir of MDR organisms, with person-to-person transmissions being a potential issue. We have identified several predictors of colonization with MDR organisms, allowing a more targeted management of high-risk residents.

Keywords: Acinetobacter baumannii; Gram-negative bacteria; MRSA; VRE; antibiotic resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Australia / epidemiology
  • Bacterial Infections / epidemiology*
  • Bacterial Infections / microbiology
  • Carrier State / epidemiology*
  • Carrier State / microbiology
  • Case-Control Studies
  • Drug Resistance, Multiple, Bacterial*
  • Female
  • Gram-Negative Bacteria / classification
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / genetics
  • Gram-Negative Bacteria / isolation & purification
  • Gram-Positive Bacteria / classification
  • Gram-Positive Bacteria / drug effects
  • Gram-Positive Bacteria / genetics
  • Gram-Positive Bacteria / isolation & purification
  • Humans
  • Long-Term Care*
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Molecular Typing
  • Nasal Mucosa / microbiology
  • Prevalence
  • Rectum / microbiology
  • Risk Assessment