Evaluate the difference in antibiotic prescribing between various levels of resident training or attending types.

Observational, retrospective study.

Tertiary-care, academic medical center in Madison, Wisconsin.

We measured antibiotic utilization from January 1, 2016, through December 31, 2018, in our general medicine (GM) and hospitalist services. The GM1 service is staffed by outpatient internal medicine physicians, the GM2 service is staffed by geriatricians and hospitalists, and the GM3 service is staffed by only hospitalists. The GMA service is led by junior resident physicians, and the GMB service is led by senior resident physicians. We measured utilization using days of therapy (DOT) per 1,000 patient days (PD). In a secondary analysis based on antibiotic spectrum, we used average DOT per 1,000 PD.

Teaching services prescribed more antibiotics than nonteaching services (671.6 vs 575.2 DOT per 1,000 PD; P < .0001). Junior resident–led services used more antibiotics than senior resident–led services (740.9 vs 510.0 DOT per 1,000 PD; P < .0001). Overall, antibiotic prescribing was numerically similar between various attending physician backgrounds. A secondary analysis showed that GM services prescribed more broad-spectrum, anti-MRSA, and anti-pseudomonal antibiotics than the hospitalist services. GM junior resident–led services prescribed more broad-spectrum, anti-MRSA, and antipseudomonal therapy compared to their senior counterparts.

Antibiotics were prescribed at a significantly higher rate in services associated with trainees than those without. Services led by a junior resident physician prescribed antibiotics at a significantly higher rate than services led by a senior resident. Interventions to reduce unnecessary antibiotic exposure should be targeted toward resident physicians, especially junior trainees.