The effect of inappropriate therapy on bacteremia by ESBL-producing bacteria

To describe the impact of empiric appropriate treatment and the risk factors associated with mortality in patients with bacteremia by E. coli, K. pneumoniae and P. mirabilis producing ESBL.

Data were reviewed in an 8-year retrospective study, and 128 bacteremias were found: 80 caused by E. coli (62.5%), 28 by K. pneumoniae (21.9%) and 20 by P. mirabilis (18.6%).

The initial antibiotic treatment, administered within 72 h after the first positive blood culture, was appropriate with carbapenems or other antimicrobial agents with documented in vitro sensitivity in 53.8 and 16% of patients, respectively. The overall mortality 21 days after diagnosis was 17.2%, and it was 14.9 and 35.2% for patients adequately and inadequately treated, respectively. At univariate analysis the p value for mortality with and without appropriate treatment was 0.05, and significant differences were found only for previous positive blood cultures (p = 0.004) and presence of septic shock at diagnosis (p = 0.006).

In this case series there was a high rate of initial appropriate empiric treatment, and only a marginal impact on mortality was found with regard to appropriate and inappropriate treatment. This report shows that the knowledge of ESBL-producing characteristics varies widely among the different case series for reasons that still have to be clarified.