Role of empirical and targeted therapy in hospitalized patients with bloodstream infections caused by ESBL-producing Enterobacteriaceae.

BACKGROUND: Bloodstream infection (BSI) due to extended-spectrum β-lactamase (ESBL) producing Enterobacteriaceae are a major cause of in-hospital mortality. The effect on survival of empirical and targeted antibiotic therapy in these patients remains controversial. METHODS: A prospective cohort study was conducted analyzing data from 94 patients (age 59 ± 21 years) with BSI due to ESBL producing strains (Sixty-one E. coli, 26 K. pneumoniae, 4 Proteus spp and 3 Enterobacter spp). RESULTS: Risk factors associated with 21-day mortality at univariate analysis were: recent administration of antibiotic therapy (p=0.049), higher SOFA score (p=0.05), ICU stay (p <0.01), hypotension at presentation (p =0.001) or septic shock (p <0.001) and bacteremia from source other than urinary tract (p=0.03). Regardless of antibiotic class used, no differences in survival were noted between patients receiving or not adequate initial antimicrobial treatment (37.1% vs 23.7% p=0.23); on the other hand, compared with the administration of other in vitro active antibiotics, the use of carbapenem as definitive therapy was associated with a significantly lower 21-day mortality (54.3% vs 28.5% p=0.02). CONCLUSIONS: These findings suggest that the administration of an adequate initial therapy is not associated with mortality in hospitalized patients with BSI due to Enterobacteriaceae. The severity of clinical conditions at presentation and the administration of carbapenems as definitive therapy seems to be really important in affecting the outcome of patients with BSI due to ESBL producing strains.