Risk Factors for Bloodstream Infections due to Extended-spectrum β-lactamase-producing Escherichia coli

Background/PurposeThe risk factors for production of extended-spectrum β-lactamases (ESBLs) have rarely been studied for bloodstream infections of Escherichia coli alone. A case-control study was undertaken to identify the risk factors associated with bloodstream infections caused by ESBL producing E. coli.MethodsFrom January 1, 2005 to June 30, 2007, all patients with a confirmed diagnosis of bloodstream infection caused by ESBL-producing E. coli were reviewed. Each patient was matched with one control subject who experienced ESBL-negative E. coli bacteremia during the same study period.ResultsOf the 97 patients diagnosed with ESBL-producing E. coli bacteremia, six were excluded owing to incomplete follow-up and missing data. Comparisons were made between 91 patients and their controls. Multivariate analysis identified urinary catheterization [odds ratio (OR) = 6.21, 95% confidence interval (CI) = 1.91–20.25; p = 0.003], prior exposure to antibiotics (OR = 2.93, 95% CI = 1.18–7.30; p = 0.021) and previous treatment with oxyimino-cephalosporins (OR = 5.16, 95% CI = 1.03–25.79; p = 0.046) as independent predictors for bloodstream infection by ESBL-producing E. coli. Conversely, patients classified as having a community-acquired infection were less likely to acquire bacteremia caused by ESBL-producing E. coli than those caused by non-ESBL-producing E. coli (OR = 0.22, 95% CI = 0.09–0.57; p = 0.002).ConclusionMore judicious use of antimicrobial agents, especially oxyimino-cephalosporins, and avoidance of urinary catheterization may decrease the possibility of ESBL-producing E. coli bacteremia in hospitalized patients.