The Impact of Hospital Antimicrobial Stewardship Programs on Antibiotic Resistance and Prescribing

Mackenzie Fuller | 2018

Advisor: Gary M. Goldbaum

Research Area(s): Clinical Epidemiology, Public Health Practice



The spread of antibiotic resistance has spurred the development of hospital antimicrobial stewardship programs (ASPs). In this observational study, the effects of hospital ASPs on antibiotic isolate susceptibility and antibiotic days of therapy (DOT) were assessed amongst inpatients at two hospitals in Seattle, WA: one children’s hospital and one general acute care hospital.


A retrospective analysis was conducted of hospital laboratory and pharmacy databases containing antibiotic susceptibility testing records of clinical isolates and antibiotic prescribing records. Using linear regression, a changepoint analysis was performed to test for slope changes in the percentage of antibiotic nonsusceptible isolates and change points and slope changes in antibiotic DOT per 10,000 patient days at each hospital.


A 0.45 (95% CI: -0.80, -0.10) decrease per quarter in the percent change in Pseudomonas aeruginosa isolates that were multidrug resistant was observed after ASP implementation compared to pre-ASP implementation at the children’s hospital. At the general acute care hospital, a 0.54 (95% CI: -1.02, -0.07) decrease per quarter in the percent change in Staphylococcus aureus isolates that were methicillin-resistant (MRSA) was observed after ASP implementation compared to pre-ASP implementation. ASP implementation was associated with significant decreases in glycopeptide DOT and monobactam DOT at both hospitals, decreases in β-lactam/β-lactamase inhibitor combination, fluoroquinolone, macrolide, and oxazolidinone DOT at the general acute care hospital, and decreases in carbapenem and rifampin DOT at the children’s hospital. ASP implementation was associated with an increase in overall cephalosporin DOT at the children’s hospital, but not the general acute care hospital.


ASPs may decrease antibiotic prescribing, MDR P. aeruginosa within children’s hospitals, and MRSA within general acute care hospitals. However, the limited linkage between prescribing and susceptibility outcomes suggests that other factors may be influencing susceptibility, and the generally limited impact overall suggests that additional strategies may be needed.