A pilot study of penicillin skin testing in patients with a history of penicillin allergy admitted to a medical ICU.

BACKGROUND

Penicillin skin testing is an accurate method to determine whether a person with a history of penicillin allergy is at risk of having an immediate reaction to penicillin. A patient with a negative reaction to a skin test may be able to use a penicillin compound safely, which could reduce the use of broad-spectrum antibiotics in this patient population.

METHODS

We prospectively studied all patients with histories of penicillin allergy who were admitted to a medical ICU during a 3-month period and who received antibiotics. Skin testing was performed with benzylpenicilloyl polylysine and penicillin G. We determined the incidence of true allergy, the percentage of patients in whom antibiotic coverage was modified, and the safety of the test.

RESULTS

Two hundred fifty-seven patients were admitted to the medical ICU of The Cleveland Clinic Foundation during the study period. Twenty-four patients (9%), labeled as penicillin allergic and receiving antibiotics, were enrolled. Three patients (13%, 3 of 21) gave histories of type I reaction to penicillin and were not skin tested. Twenty patients (95%, 20 of 21) had negative skin test reactions to penicillin and positive skin test reactions to histamine control. One patient (4%, 1 of 21) with negative skin test reactions to both penicillin and histamine control had a test dose challenge with piperacillin that was well tolerated. There were no adverse events. Antibiotic coverage was changed in 10 patients (48%) as a result of skin testing.

CONCLUSION

Most patients with histories of allergy to penicillin have negative reactions to skin tests and may receive penicillin safely. Penicillin skin testing can be utilized as a safe and effective strategy to reduce the use of broad-spectrum antibiotics.