Prevalence of multidrug-resistant organisms and risk factors for carriage in long-term care facilities: a nested case-control study.
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.
Centre for Medicine Use and Safety, Monash University, Melbourne, Victoria, Australia.
Ching Jou
CJ
Lim
Department of Infectious Diseases, Alfred Health, Melbourne, Victoria, Australia Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia.
Allen C
AC
Cheng
Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia.
Jacqueline
J
Kennon
Department of Infectious Diseases, Alfred Health, Melbourne, Victoria, Australia Infection Prevention and Healthcare Epidemiology Unit, Alfred Health, Melbourne, Victoria, Australia Microbiology Department, Alfred Health, Melbourne, Victoria, Australia.
Denis
D
Spelman
Microbiology Department, Alfred Health, Melbourne, Victoria, Australia.
Dayna
D
Hale
Nursing Service, Caulfield Hospital, Alfred Health, Melbourne, Victoria, Australia.
Gabrielle
G
Melican
University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
Hanna E
HE
Sidjabat
University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
David L
DL
Paterson
Centre for Medicine Use and Safety, Monash University, Melbourne, Victoria, Australia.
David C M
DC
Kong
Department of Infectious Diseases, Alfred Health, Melbourne, Victoria, Australia Department of Microbiology, Monash University, Melbourne, Victoria, Australia anton.peleg@monash.edu.
Anton Y
AY
Peleg
D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D016022:Case-Control Studies; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006090:Gram-Negative Bacteria / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D009297:Nasal Mucosa / Q000382:microbiology; D015995:Prevalence; D012007:Rectum / Q000382:microbiology; D018570:Risk Assessment
Acinetobacter baumannii; Gram-negative bacteria; MRSA; VRE; antibiotic resistance