JAC Advance Access originally published online on June 23, 2009
Journal of Antimicrobial Chemotherapy 2009 64(3):635-641; doi:10.1093/jac/dkp220
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Original research |
Nursing homes as a reservoir of extended-spectrum β-lactamase (ESBL)-producing ciprofloxacin-resistant Escherichia coli
1 Department of Microbiology, Belfast City Hospital, Belfast BT9 7AD, UK 2 Eastern Health and Social Services Board, 12 Linenhall Street, Belfast, BT2 8BS, UK 3 Communicable Disease Surveillance Centre (Northern Ireland), Belfast City Hospital, Belfast BT9 7AD, UK 4 Northern Ireland Clinical Research Support Centre, Royal Hospitals, Grosvenor Road, Belfast BT12 6BA, UK 5 Department of Medicine, University of Cape Town, South Africa 6 Antibiotic Resistance Monitoring and Reference Laboratory, Centre for Infections, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
Received 10 March 2009; returned 28 April 2009; revised 28 May 2009; accepted 29 May 2009
* Corresponding author. Tel: +44-2890263661; Fax: +44-2890263991; E-mail: paul.rooney{at}belfasttrust.hscni.net
Background: To assess the prevalence and risk factors for faecal carriage of fluoroquinolone-resistant, extended-spectrum β-lactamase (ESBL)-producing, Escherichia coli (MDR E. coli) among residents in nursing homes in Northern Ireland.
Methods: Between January 2004 and May 2006, retrospective histories of hospital admissions, antimicrobial treatment and co-morbidities were collected. Faecal samples were cultured for MDR E. coli. These isolates and their ESBL genes were typed by a reference laboratory.
Results: Of the 294 patients included in the study, faecal samples from 119 (40.5%) grew MDR E. coli. The proportion of carriers in the different homes ranged from 0% to 75%. Epidemic strain A belonging to the ST131, O25:H4 lineage with the CTX-M-15 enzyme accounted for 58 (49%) of all isolates; its proportion varied from 0% to 100% among homes. Fifty-one percent of carriers had no history of recent hospital admission and only 13.5% had a known history of ESBL E. coli colonization or infection. In a multivariate logistic regression model, days of fluoroquinolone use [odds ratio (OR) = 1.33, 95% confidence interval (CI) 1.04–1.69, P = 0.02] and a history of urinary tract infection (OR = 2.56, 95% CI 1.37–4.78, P = 0.003) were the only variables independently associated with the risk of carrying MDR E. coli.
Conclusions: The high level of faecal carriage of MDR E. coli in nursing home residents demonstrates their importance as a reservoir population. Public health measures to combat spread of these organisms should address the needs of this group.
Keywords: colonization pressure , CTX-M-15 , faecal carriage , ST131 E. coli