The efficacy of cefmetazole and flomoxef (CF) for the treatment of patients with extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) bacteremia (ESBL-CF group) was compared with that of carbapenem treatment for ESBL-EC patients (ESBL-carbapenem group) and with that of CF treatment in patients with non-ESBL-EC bacteremia (non-ESBL-CF group). Adult patients treated for E. coli bacteremia in four hospitals were retrospectively evaluated. The 30-day mortality rates in patients belonging to the ESBL-CF, ESBL-carbapenem, and non-ESBL-CF groups were compared as 2 (empirical and definitive therapy) cohorts. The adjusted hazard ratios (aHRs) for mortality were calculated using Cox regression models with weighting according to the inverse probability of propensity scores for receiving CF or carbapenem treatment. The empirical-therapy cohort included 104 patients (ESBL-CF, 26; ESBL-carbapenem, 45; non-ESBL-CF, 33), and the definitive-therapy cohort included 133 patients (ESBL-CF, 59; ESBL-carbapenem, 54; non-ESBL-CF, 20). The crude 30-day mortality rates for patients in the ESBL-CF, ESBL-carbapenem, and non-ESBL-CF groups were, respectively, 7.7%, 8.9%, and 3.0% in the empirical-therapy cohort and 5.1%, 9.3%, and 5.0% in the definitve-therapy cohort. In patients without hematological malignancy and neutropenia, CF treatment for ESBL-EC patients was not associated with mortality compared with carbapenem treatment (empirical-therapy cohort: aHR, 0.87; 95% confidence interval [CI], 0.11 to 6.52; definitive therapy cohort: aHR, 1.04; CI, 0.24 to 4.49). CF therapy may represent an effective alternative to carbapenem treatment for patients with ESBL-EC bacteremia for empirical and definitive therapy in adult patients who do not have hematological malignancy and neutropenia.
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