Routine Penicillin Skin Testing in Hospitalized Patients with a History of Penicillin Allergy

Background: In selected inpatient settings, penicillin skin testing has been shown to affect antibiotic use. Routine penicillin skin testing has not been studied in hospitalized patients with a history of penicillin allergy.

Objectives: To determine whether routine penicillin skin testing at a large regional hospital affected antibiotic use and/or antibiotic side effects in hospitalized persons with a history of penicillin allergy.

Methods: A convenience sample of patients was penicillin skin tested from among those who had a history of penicillin allergy during any hospitalization from September 2002 through February 2003. Discharge coding was used to identify two age- and sex-matched control patients who had a history of penicillin allergy but who did not receive skin testing while hospitalized. All inpatient and outpatient antibiotic use, positive results of bacteriology culture obtained at any time from August 2002 through March 2003, and coded adverse reactions to medications were identified.

Results: Of the 13,172 patients admitted to the hospital during the study period, 1627 (12.35%) had a history of penicillin allergy; of these 1627 patients, 141 (8.7%) received skin testing. Use of antibiotic agents was common: 79.4% of all study subjects received at least one antibiotic agent. Penicillins were used in substantially more cases than controls. Cephalosporins were the most widely used class of antibiotic agents, accounting for 26.8% of all antibiotic courses used. Of the six antibiotic-associated adverse drug reactions in five (1.2%) of the study subjects, one adverse reaction was associated with a penicillin, and one was associated with a cephalosporin.

Conclusions: Routine penicillin skin testing in hospitalized patients is safe and allows more appropriate antibiotic use. To ensure that accurate information is available to support clinical care, hospitals should maintain a single centralized system for collecting data on drug allergy and testing.