Propensity-matched analysis of the impact of extended-spectrum β-lactamase production on adults with community-onset Escherichia coli, Klebsiella species, and Proteus mirabilis bacteremia

Background: The presence of extended-spectrum β-lactamase (ESBL) in Escherichia coli, Klebsiella species, and Proteus mirabilis (EKP) is of great microbiological and clinical importance. The study dealing with the direct impact of ESBL producers on the outcome of patients with community-onset bacteremia is lacking. Methods: Adults with community-onset EKP bacteremia were recruited retrospectively during a 6-year period. ESBL producers were determined according to ESBL phenotype. ESBL patients were compared on a 1:2 basis with non-ESBL patients by using propensity-score matching (PSM) calculated based on independent predictors of 28-day mortality. Results: Of the 1141 eligible adult patients, 65 (5.7%) caused by ESBL producers. Significant differences between the two groups were discovered in the proportions of patients with critical illness (a Pitt bacteremia score ≥ 4) at bacteremia onset, inappropriate empirical antibiotic therapy, bacteremia because of urosepsis and pneumonia, and several comorbidities. In a PSM analysis after controlling for six independent predictors—critical illness at bacteremia onset, underlying fatal comorbidities (McCabe classification), inappropriate empirical antibiotic therapy, comorbidities with liver cirrhosis, bacteremia because of urosepsis and pneumonia—a appropriate matching between two groups (ESBL group, 60 patients; non-ESBL group, 120) were observed in age, causative microorganism, bacteremia severity, major comorbidities, comorbidity severity, and major bacteremia source. Consequently, a strong relationship between ESBL producers and poor prognosis was highlighted. Conclusions: The adverse influence of ESBL producers on clinical outcomes was presented with respect to adults with community-onset EKP bacteremia. Establishing a predictive scoring algorithm for identifying patients at risk of ESBL-producer infections is crucial.