Infections caused by extended-spectrum beta-lactamase (ESBL)-producing bacteria are associated with worse outcomes and have limited treatment options. Carbapenems remain the drug of choice for these infections due to evidence of a mortality benefit and the mixed clinical efficacy associated with piperacillin/tazobactam (PTZ). Though definitive treatment for ESBL infections is well defined, evidence for appropriate empiric therapy remains inconclusive, and the role of rapid molecular assays that identify ESBL has not been evaluated. This multicenter retrospective study at nine Baylor Scott & White Health sites included patients who had positive blood cultures with ESBL-producing bacteria identified by rapid molecular assay and were empirically prescribed PTZ or carbapenems. A total of 117 patients were included in the study; 66 received empiric PTZ and 51 received carbapenems. Results showed no difference in hospital mortality (3% vs 7.8%, P ¼ 0.4), hospital length of stay (6.1% vs 5.9%, P ¼ 0.88), intensive care unit length of stay (4.7% vs 3.3%, P ¼ 0.39), or recurrent ESBL bacteremia (7.6% vs 7.8%, P ¼ 0.99) between the PTZ and carbapenem empiric treatment groups, respectively. In the era of rapid molecular assays, these results suggest that empiric PTZ use and avoidance of empiric carbapenem therapy in the first 24 hours of infection can be considered until a microbiological diagnosis is confirmed.

BackgroundInfections due to extended spectrum β-lactamase (ESBL) producing bacteria are problematic due to the association with worse outcomes and limited treatment options. Carbapenems (CBPs) remain the drugs of choice for these infections due to evidence of a mortality benefit and the mixed clinical efficacy associated with piperacillin/tazobactam (PTZ) despite often reported in vitro activity. While definitive treatment for these infections has been well-defined, evidence for appropriate empiric therapy remains inconclusive. Rapid molecular assays capable of identifying ESBL markers may aid in switching to appropriate definitive therapy sooner and spare empiric carbapenem use.MethodsThis multicenter retrospective study at 9 sites at Baylor Scott & White Health included patients with a positive blood culture with ESBL-producing bacteria identified by rapid molecular assay from January 1, 2014 to September 22, 2017 and were empirically prescribed either PTZ or a CBP. Patients were excluded if they continued PTZ for more than 24H after identification or did not receive a CBP for definitive therapy. Categorical data were analyzed using the Fisher’s exact test and continuous data were evaluated using the t-test and Wilcoxon rank-sum test.Results117 patients met inclusion criteria of which 66 and 51 received empiric PTZ or CBPs, respectively. Baseline characteristics were similar between the groups, including suspected source of bacteremia, prior hospital stay, prior antibiotic therapy, history of positive non-blood ESBL culture, ICU admission, and time to ESBL identification. There was no difference in hospital mortality (3 vs. 7.8%, P = 0.4), hospital length of stay (6.1 vs. 5.9%, P = 0.88), ICU length of stay (4.7 vs. 3.3%, P = 0.39) or recurrent ESBL bacteremia (7.6 vs. 7.8%, P = 0.99) between those that received PTZ or a CBP for initial treatment, respectively.ConclusionThis study in patients with ESBL bacteremia showed similar outcomes when treated empirically with PTZ or a CBP. In the era of rapid molecular assays, these results suggest that empiric PTZ use and avoidance of empiric CBP therapy in the first 24H of infection can be considered until a microbiological diagnosis is confirmed.Disclosures All authors: No reported disclosures.