Incidence of Antimicrobial Resistant Escherichia coli Urinary Tract Infections in the Australian Capital Territory

Abstract

<p>Introduction: The prevalence of antimicrobial resistance in urinary <em>Escherichia coli</em> <em>(E. coli)</em> is increasing in Australia but incidence and risk factors for resistance are not well described. We evaluated the incidence of antimicrobial resistant <em>E. coli</em> urinary tract infections (UTI) in a cohort of Australian Capital Territory (ACT) residents. The associations of age, gender and urine sample source with risk of resistant infections were also investigated.</p> <p>Methods: We utilised laboratory-based retrospective data from all ACT residents who submitted urine samples to ACT Pathology between January 2009 and December 2013.</p> <p>Results: A total of 146,915 urine samples from 57,837 ACT residents were identified over 5 years. The mean age of residents was 48 years (SD 26 years) with 64.4% female. The incidence of single drug resistant <em>E. coli</em> UTI was high for ampicillin, trimethoprim, and cefazolin (6.8%, 3.5%, and 1.9% respectively). No pandrug-resistant <em>E. coli</em> UTI was detected. Five year incidences of multi-drug and extensively drug-resistant <em>E.coli</em> UTI were 1.9% and 0.2% respectively. In multivariate logistic regressions, female age and sex over 38 years were significantly associated with single and multi-drug resistance. The risk of single-drug resistance was significantly higher in samples from after hours general practices compared to hospitals, office-hours general practices, community and specialist health services (adjusted odds ratio (OR) and 95% confidence intervals (CI) 2.6 (2.2-3.1)).</p> <p>Conclusions: In this study, incidence of multi-drug and extensively drug resistant <em>E.coli</em> UTI are low in comparison to international rates. Our findings have significant implications for antimicrobial prescribing.</p>