Risk factors for bloodstream infections caused by extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae

ABSTRACT

The objective of this study was to identify risk factors for bacteremia by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. Retrospective case-control study performed in a 450-bed acute care academic tertiary hospital in Barcelona, Spain. Cases included 53 patients with ESBL-producing E. coli or K. pneumoniae bacteremia, and 159 controls with non-ESBL-producing E. coli or K. pneumoniae bacteremia. Controls were matched in a 3:1 ratio to case patients according to species of infecting organism, age, and severity of illness in the 24-48h before blood sample collection for culture calculated by the Simplified Acute Physiology Score (SAPS II) system. Previous antimicrobials were more frequently administered to cases than to controls (56.5 percent vs 17 percent, p < 0.001). Binary logistic regression showed that the number (> 2) of different families of antimicrobials received within 90 days before bloodstream infection was the only predictor of ESBL-producing E. coli or K. pneumoniae in blood culture (OR = 2.29, 95 percent CI 1.35-3.88, p = 0.002). Conclusion: Previous use of different families of antimicrobials (more than two) in patients with bloodstream infection caused by E. coli or K. pneumoniae increased the risk for ESBL-producing strains.