Impact of an Antimicroibal Stewardship Bundle of Rapid Identification of Methicillin Susceptibility and Active Intervention on Treatment of Staphylococcus aureus Bacteremia

Abstract

Background Staphylococcus aureusbacteremia (SAB) is a major source of morbidity and mortality. Studies show rapid initiation of appropriate antibiotic therapy is essential to treatment and optimal therapy depends upon antibiotic susceptibility.MethodsUsing a quasi-experimental pre-post intervention study we evaluated a bundled antimicrobial stewardship rapid identification and susceptibility testing protocol. The pre-intervention group included all patients treated for SAB at our hospital between April and Sept 2015; the post-intervention group was between April and Sept 2016. We implemented combined rapid identification by MALDI-TOF with a modified immunochromatographic assay for penicillin–binding protein 2a to differentiate MSSA and MRSA. Identification and susceptibility results were communicated to the primary team per usual protocol and to an antimicrobial stewardship pharmacist for intervention. The primary outcome was time to optimal antibiotic therapy calculated as the difference in time from the first dose of antibiotic therapy to the discontinuation time of the non-optimal antibiotic, for patients receiving combination therapy or first dose of optimal therapy, determined using a predefined protocol developed in collaboration with the Infectious Diseases (ID) consult service. Additional outcomes included time to pathogen identification, time to ID consult, time to source control, length of hospital stay (LOS), intensive care unit LOS, inpatient-days of therapy, and in-hospital mortality. Outcomes were compared using the χ2 test, or Student’s t-test for independent samples.Results74 pre-intervention and 55 post-intervention patients were included. Time in days to optimal therapy (1.7 ± 1.2 vs.. 2.5 ± 1.6, P = 0.003), total time to pathogen identification (1.5 ± 0.5 vs.. 2.7 ± 0.6, P < 0.001) and time to ID consult (1.6 ± 1.5 vs.. 2.8 ± 2.4, P = <0.001) were significantly shorter in the intervention group. All other outcomes were not statistically significantly different between groups.ConclusionWe demonstrate significant improvement in time to pathogen identification, optimal therapy, and ID consult utilizing rapid pathogen identification and susceptibility testing coupled with antimicrobial stewardship pharmacist intervention.Disclosures E. Ernst, Merck Sharp and Dohme: Consultant, Consulting fee.