Community-onset extended-spectrum β-lactamase (ESBL) producing Escherichia coli: Importance of international travel
Introduction
Extended-spectrum β-lactamase (ESBL) producing Escherichia coli is an emerging major pathogen worldwide.1 Unlike most other anti-microbial-resistant pathogens that are associated with admission to hospitals, ESBL-producing E. coli are predominantly community-onset pathogens.1, 2, 3, 4, 5, 6, 7, 8 Hospital-based studies have associated ESBL acquisition in Enterobactericeae with a number of factors including intensive care unit admission, prolonged hospitalization, use of anti-microbials, older age, and use of medical devices.9, 10, 11, 12, 13, 14, 15, 16 Investigations of community-onset infections have similarly reported that recent hospitalization, prior antibiotic treatment, older age, diabetes, and male gender are associated with ESBL production.16, 17, 18, 19, 20, 21 However, previous studies have focused on assessment of risk factors associated with prior medical care and hospitalization and have not differentiated between those patients who have healthcare associated as compared to community-acquired infections.22 Furthermore, by studying selected sub-populations such as those presenting to major acute care centers,16, 17, 19, 20, 21 a potentially large segment of patients with community-acquired ESBL-producing E. coli infections have not been included in previous risk factor evaluations.
In order to best define risk factors for acquiring an infectious disease, population-based studies where all incident cases occurring among a defined population at risk are included are optimal. No studies utilizing such a design have been previously reported, and the risk factors for developing community-acquired ESBL-producing E. coli infections have not been well defined. The objective of this study was to conduct active, prospective, population-based surveillance in order to define risk factors for developing community-onset ESBL-producing E. coli infections among residents of a large Canadian health region.
Section snippets
Study population
The Calgary Health Region (CHR) provides all publicly funded healthcare services to the 1.2 million residents of the cities of Calgary and Airdre and numerous adjacent surrounding communities covering an area of more than 37,000 km2 in the province of Alberta, Canada.23 Acute care is provided principally through one pediatric and three major adult hospitals that have approximately 2000 acute care beds and 100,000 discharges yearly. All CHR residents with incident community-onset ESBL-producing
Results
During the two years of prospective surveillance, a total of 247 incident community-onset ESBL-producing E. coli isolates were identified of which 177 (72%; 7.6 per 100,000/year) were further classified as community acquired, and 70 (28%; 3.0 per 100,000/year) as healthcare associated. Classification as healthcare associated was on the basis of receipt of intravenous therapy or specialized clinical care in the previous 30 days in 19 cases, hospitalization for two or more days in the preceding
Discussion
Our demonstration that international travel is a major risk factor associated with developing an ESBL-producing E. coli infection in our region is both an important and novel finding. While anecdotal reports and one cohort study have raised travel as a risk factor for acquisition of resistant E. coli, to our knowledge ours is the first to formally quantify the magnitude of specific country travel risk associated with acquisition ESBL-producing E. coli.35, 36, 37 Sannes and colleagues conducted
Acknowledgments
We thank Kaye Holt and Terry Ross for data entry and database management, Paula Yung and Sylvain DeRepentigny at Statistics Canada for providing travel data, and Jim Si and Dana Nelson for assistance with establishment and figurative display of social district assignments. This study was funded by The Dean's Starter Grant and the 2004 AMMI Canada/Bayer Healthcare Young Investigator's Award (KBL).
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