ESBL-producing Escherichia coli bacteraemic urinary tract infections: Clinical and economic burden and antimicrobial stewardship opportunities in a retrospective cohort study

BACKGROUND: The study aimed to assess the clinical and economic impact of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli bacteraemic UTIs (Ec-BUTI) and to evaluate the possibility of developing antimicrobial stewardship interventions. METHODS: Retrospective single-centre cohort study included all consecutive episodes of Ec-BUTI requiring hospitalisation from September 2020 to February 2023. PRIMARY OUTCOME: clinical failure. SECONDARY OUTCOME: hospital resource consumption, length of stay, 30-d recurrence and mortality and 90-d readmissions. Antimicrobial stewardship interventions were evaluated. A propensity score matching analysis was performed. RESULTS: Three hundred ten E. coli-BUTI episodes were included; 86 caused by ESBL-producing strains. The ESBL group had greater comorbidity burden than the non-ESBL group (median Charlson index 4 [IQR 2-6] vs. 2 [IQR 1-4]; P < 0.001) and more frequent inappropriate empirical therapy (40.7% vs. 3.6%; P < 0.001). Overall, an intravenous-to-oral switch was made within the first week in 172 (55.5%) episodes. In the ESBL group, an oral switch was made in 17 patients (19.7%), while no oral option was available in 48 (55.8%) based on susceptibility results. After adjustment, ESBL was not significantly associated with clinical failure (aOR 1.85, 95% CI 0.33-10.48), recurrence (aOR 1.98, 95% CI 0.70-5.62) or mortality (aHR 2.12, 95% CI 0.43-10.38). However, ESBL-producing Ec-BUTI was associated with longer stays (P = 0.014), higher pharmacy costs (P < 0.001) and independently increased overall hospitalisation costs by a median of €1493 (P = 0.022). CONCLUSIONS: ESBL-producing Ec-BUTI was associated with greater healthcare resource consumption and costs, though not with worse clinical outcomes. These findings highlight the economic impact of antimicrobial resistance and support antimicrobial stewardship.