Use of Penicillin Skin Testing as an Antimicrobial Stewardship Initiative: Clinical and Economic Evaluation at a Community Health System

BACKGROUND: Commonly reported penicillin allergies result in limited treatment options, increased healthcare costs, and increasing resistance with the use of broad-spectrum agents. By providing penicillin skin testing (PST) to patients with a penicillin allergy, there is potential to reduce the use of carbapenems, aztreonam, vancomycin, and other broad-spectrum agents, resulting in cost savings and unnecessary overuse. This study examined clinical and economic outcomes of antimicrobials prescribed before and after PST. METHODS: This nonrandomized, observational chart review examined adult patients admitted over an open enrollment period of 100 patients who completed PST for a self-reported penicillin allergy. The study included all patients who met inclusion criteria and completed the test per protocol. Administration of the test utilized a stewardship pharmacist-driven, nursing administered, protocol that has three phases: puncture, intradermal, and oral challenge (optional phase). The primary outcome assessed was change made to antimicrobial regimen directly related to PST. A secondary outcome assessed was cost savings associated with PST. RESULTS: Over 13 months, 116 patients were consulted for PST with 100 patients completing PST per protocol. Self-reported allergies consisted of IgE-mediated and unknown in 52% and 30% of patients respectively. Seventy-one of 98 patients who tested negative (73%) had changes directly made to their antimicrobial regimens related to PST after intervention from the stewardship pharmacist. Thirty-four patients who had received carbapenems were changed directly to a penicillin or cephalosporin. A previous evaluation at our institution showed an average total antimicrobial acquisition cost savings per patient to be $314.75, which would result in $22,347.25 in direct savings for all patients evaluated. CONCLUSION: PST led to immediate antimicrobial de-escalation in the majority of patients who tested negative. Most of these patients were transitioned to optimal therapy or de-escalated from carbapenem therapy. A total direct cost savings for the institution over the course of 13 months exceeded $20,000. Our study confirmed the overall utility of PST as a cost effective antimicrobial stewardship tool, especially as a carbapenem-sparing strategy. DISCLOSURES: B. Jones, ALK: Consultant, Grant Investigator and Scientific Advisor, Consulting fee, Grant recipient and Speaker honorarium; C. Bland, ALK: Grant Investigator and Scientific Advisor, Grant recipient and Speaker honorarium