Impact of Implementing an Antimicrobial Stewardship Program for Optimizing Antibiotic Treatment in Gram-negative Bacilli Bacteremia

Background: Antibiotic Stewardship Programs (ASP) have improved empirical and directed antibiotic treatment in Gram-negative Bacilli (GNB) bloodstream infections. A decrease in mortality, readmission, and length of hospitalization has been reported. Materials and Methods: A pre-post-quasi-experimental study was conducted between November and April 2015-2016 (pre-intervention period), 2016-2017, 2017-2018, and 2018-2019 (post-intervention periods), to analyse the impact of ASP on empirical, directed, and entire treatment optimization, as well as mortality, readmission, and length of hospitalization, in hospitalized patients with Gram-negative bacilli (GNB) bloodstream infections. Results: One hundred seventy-four patients were included (41 in the pre-intervention group, 38 in the first-year post-intervention group, 50 in the second-year post-intervention group, and 45 in the third-year post-intervention group). There was a significant improvement in directed treatment optimization (43.9% in the pre-intervention group, 68.4% in the first-year post-intervention group, 74% in the second-year post-intervention group, and 88.9% in the third-year post-intervention group, P <0.001), as well as in entire treatment optimization (19.5%, 34.2%, 40.0%, and 46.7%, respectively, P =0.013), with increased optimal directed (adjusted odds ratio [aOR], 3.71; 95% confidence interval [CI], 1.60-8.58) and entire treatment (aOR, 3.31; 95% CI, 1.27-8.58). Although a tendency toward improvement was observed in empirical treatment after ASP implementation, it did not reach statistical significance (41.5% vs. 57.9%, P =0.065). No changes in mortality, readmission, or length of hospitalization were detected. Conclusion: ASP implementation improved both directed and entire treatment optimization in patients with GNB bloodstream infections over time. Nevertheless, no improvement was found in clinical outcomes such as mortality, readmission, or length of hospitalization.