Risk factors for bloodstream infection caused by extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae: A focus on antimicrobials including cefepime

Background Extended-spectrum β-lactamase (ESBL)-producing pathogens represent increasing challenges to physicians because of rising prevalence, high mortality, and challenging treatment. Identifying high risks and early appropriate therapy is critical to favorable outcomes. Methods This is a 5-year retrospective case-case-control study performed at the Detroit Medical Center on adult patients with bloodstream infection (BSI) caused by ESBL-producing and non-ESBL-producing Escherichia coli or Klebsiella pneumoniae, each compared with uninfected controls. Data were collected from December 2004-August 2009. Multivariate analysis was performed using logistic regression. Results Participants included 103 patients with BSI caused by ESBL-producing pathogens and 79 patients with BSI caused by pathogens that did not produce ESBLs. The mean age of patients in the ESBL group was 67 years; of the patients, 51% were men, 77% were black, and 38% (n = 39) died in hospital. The mean age of patients in the non-ESBL group was 58 years; of the patients, 51% were men, 92% were black, and 22% (n = 17) died in hospital. On multivariate analysis, predictors of BSI caused by ESBL-producing pathogens included central venous catheter (odds ratio [OR], 29.4; 95% confidence interval [CI], 3.0-288.3), prior β-lactam-/β-lactamase-inhibitor therapy (OR, 28.1; 95% CI, 1.99-396.5), and prior cefepime therapy (OR, 22.7; 95% CI, 2.7-192.4). The only risk factor for BSI caused by non-ESBL-producing pathogens was urinary catheter insertion (OR, 18.2; 95% CI, 3.3-100.3). Conclusion Prior antimicrobial therapy, particularly with β-lactam, was the strongest unique risk factor for BSI caused by ESBL-producing E coli or K pneumoniae.