Program Schedule

Evaluation of Oxacillin Consumption Following Implementation of a Usage Restriction Protocol: A Drug Use Evaluation and Cost Savings Analysis

Session: Poster Abstract Session: Antibiotic Stewardship
Thursday, October 9, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC


Anti-staphylococcal β-lactams, such as oxacillin (OXA), are considered the drugs of choice for the treatment of methicillin-sensitive Staphylococcus aureus (MSSA) infections. Cefazolin (CEZ) has been shown to be equally efficacious to OXA for many MSSA infection types and is less costly than OXA.  Our Antimicrobial Stewardship Program (ASP) implemented a use restriction protocol in July 2013 to limit OXA usage to patients with a central nervous system infection or with Infectious Diseases physician approval.


The Centers for Disease Control and Prevention Antimicrobial Use and Resistance Module was utilized to quantify OXA and CEZ consumption institution-wide in two time periods: August 2012 to April 2013 (pre-restriction) and August 2013 to April 2014 (post-restriction). Days of therapy (DOTs) were normalized using 1000 patient location days (LDs) as a denominator.  Calendar months were compared directly pre- and post-restriction to minimize temporal differences in antimicrobial usage. OXA and CEZ total DOTs drug costs from each study period were tabulated using purchase data and then compared.  Patients receiving OXA were assessed retrospectively for adherence to the restriction protocol criteria.


Mean OXA usage has decreased significantly following implementation of the restriction protocol (1.82 v. 3.91 DOTs/1000 LDs; P=0.0013). The by month comparison showed a trend toward decreased OXA DOTs/1000 LDs across all months except one after implementation.  42 of 50 patients (84%) receiving OXA in the post-restriction study period met criteria for use.  CEZ usage increased significantly post-implementation (72.6 v. 67.0 DOTs/1000 LDs; P=0.006).  Reduction in OXA usage was associated with an overall cost savings of $52,309 during the study period. Projected annualized cost savings after OXA restriction are approximately $70,000.


Implementation of an OXA restriction by our ASP has been successful at our institution. Usage of OXA has decreased from the previous calendar year and this program resulted in notable drug cost savings. Similar restrictions may offer an opportunity for substantial cost savings among other antimicrobial stewardship programs.

Elise Gilbert, PharmD1,2, Nathaniel J. Rhodes, PharmD1,2, Marc Scheetz, PharmD, MSc1,2, Sarah Sutton, MD1,3, Teresa Zembower, MD, MPH1,3, Viktorija Barr, PharmD1,4 and John Esterly, PharmD1,5, (1)Northwestern Memorial Hospital, Chicago, IL, (2)Midwestern University Chicago College of Pharmacy, Downers Grove, IL, (3)Northwestern University Feinberg School of Medicine, Chicago, IL, (4)Rosalind Franklin University - College of Pharmacy, North Chicago, IL, (5)Chicago State University School of Pharmacy, Chicago, IL


E. Gilbert, None

N. J. Rhodes, None

M. Scheetz, None

S. Sutton, None

T. Zembower, None

V. Barr, None

J. Esterly, None

Findings in the abstracts are embargoed until 12:01 a.m. EDT, Oct. 8th with the exception of research findings presented at the IDWeek press conferences.

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