Nursing homes as a reservoir of extended-spectrum -lactamase (ESBL)-producing ciprofloxacin-resistant Escherichia coli

Background To assess the prevalence and risk factors for faecal carriage of fluoroquinolone-resistant, extended-spectrum ß-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