Incidence and clinical impact of extended-spectrum-beta-lactamase (ESBL) production and fluoroquinolone resistance in bloodstream infections caused by Escherichia coli in patients with hematological malignancies

OBJECTIVES: To identify risk factors for mortality in patients suffering from hematological malignancies with concurrent bacteremia caused by Escherichia coli. Particular attention was focused on defining the impact of extended-spectrum-beta-lactamase (ESBL) production and fluoroquinolone resistance by the bacterial isolates on mortality. MATERIALS AND METHODS: A retrospective eight-year cohort study design was employed. The outcome measured was death within 30 days of the first positive blood culture. Survivor and non-survivor subgroups were compared to identify predictors of mortality. RESULTS: A total of 62 episodes of bacteremia caused by E. coli were analyzed. The overall incidences of ESBL production and fluoroquinolone resistance were 41.9% and 62.9%, respectively. The overall 30-day mortality rate was 20.9% (13/62). In a multivariate analysis, significant predictors of mortality were inadequate initial antimicrobial therapy (OR=14.96, 95% CI 1.95-114.51; P=0.009), infection caused by ESBL-producing isolates (OR=8.84, 95% CI 1.48-52.91; P=0.01), and prolonged neutropenia (OR=8.10, 95% CI 1.29-50.57; P=0.02). CONCLUSIONS: Sound knowledge of the local distribution of pathogens and their susceptibility patterns and prompt initiation of effective antimicrobial treatment are essential in patients suffering from hematological malignancies with BSIs caused by E. coli.