In low prevalence countries such as Australia and New Zealand, community-onset cephalosporin-resistant Escherichia coli may be propelled by “export” from health care facilities and “import” after travel to high prevalence areas, according to data from a recent study.
Moreover, the Community Onset ESBL and AmpC E. coli, or COOEE, study established 6 months as a high-risk period of expanded-spectrum cephalosporin resistance after health care exposure.
In the multisite, prospective, case-control study, 91 patients with expanded-spectrum cephalosporin-resistant (ESC-R) E. coli and 91 control patients were identified for analysis.
Control patients had community onset ESC-susceptibleE. coli. The study participants were recruited from six tertiary centers in Australia and New Zealand.
Health care exposure was evaluated using Friedman criteria for health care-associated infection, as well as a continuous model of the chronological risk for ESC-R E. coli after health care exposure. Site of infection was ascertained by the researchers based on accessible information. Travel within the past year was analyzed by region, and multivariate logistic regression was used to determine risk factors for ESC-R among patients with E. coli.
The researchers found that the among thosepatients, the following factors were associated with increased risk ESC-R: birth on the Indian subcontinent (OR=11.13; 95% CI, 2.17-56.98); urinary tract infection within the previous year (OR per infection=1.43; 95% CI, 1.13-1.82); travel to Southeast Asia, China, Indian subcontinent, Africa and the Middle East (OR=3.089; 95% CI, 1.29-7.38); previous use of trimethoprim-sulfamethoxazole or an ESC (OR=3.665; 95% CI, 1.3-10.35); and health care exposure within the past 6 months (OR=3.16; 95% CI, 1.54-6.46).
The bla(CTX-M) extended-spectrum beta-lactamase gene was found to be prevalent (83%) in the ESC-R E. coli cases, and the pandemic clone ST131 was common (45%) in these cases.
Besides the other key findings, the researchers said this study was useful in identifying a risk period for ESC-R after health care exposure.
“We established that 6 months is a practical, evidence-based definition for the duration of increased risk of a community-onset E. coli isolate harboring ESC-R after health care exposure,” the researchers wrote. “Overall, the significant contribution of health care exposure (OR=3.15) as an ongoing ‘exporter’ of resistant infection in a low-prevalence setting highlights the importance of controlling expanded-spectrum cephalosporin resistance in the health care system.”
Disclosure: The researchers report no relevant financial disclosures.