Solenksy R, Earl HS, Gruchalla RS. Arch Intern Med. 2002;162:822–826
Purpose of the Study.
To determine the rate of penicillin (PCN) resensitization in adults with a history of PCN allergy after exposure to multiple courses of PCN.
Fifty-three adults with a clinical history consistent with an acute, immunoglobulin E (IgE)-mediated reaction to PCN.
Adults >18 years of age who had a history consistent with an acute, IgE-mediated reaction to PCN were recruited for the study. Participants underwent PCN skin testing and those with negative skin tests received 250 mg of PCN orally. Study participants were then provided with a 10-day course of PCN to continue at home. After completion of the 10-day course of PCN, the participants returned for repeat skin testing and if the test continued to be negative, they repeated a 10-day course of PCN. This process continued until three 10-day courses of PCN had been completed and the participants had undergone a total of 4 sets of PCN skin tests.
Fifty-eight participants met entry criteria for the study and underwent PCN skin testing. Five (9%) participants had positive PCN skin tests and were excluded from further participation. Of the 53 who continued in the study, 25 (47%) gave a prior history of urticaria or angioedema after taking penicillin, 9 (17%) reported anaphylaxis, and 19 (36%) reported a pruritic rash. The mean length of time since the most recent PCN reaction was 25 years. Forty-six participants completed the protocol and all tolerated the 3 courses of PCN and maintained negative skin test results. This resensitization rate of 0% had an upper limit of the 95% confidence interval (CI) of 2.1%. Of the 7 participants who withdrew from the study, 2 relocated, 1 decided not to continue, 1 had a vaginal yeast infection, 1 was lost to follow-up, and 2 had adverse reactions that ultimately proved not to be IgE-mediated as evidenced by subsequent negative PCN skin tests in both.
This study is the first to report that adults with a history of PCN allergy, who subsequently have negative PCN skin tests, are not at increased risk of PCN resensitization after multiple courses of the antibiotic.
Studies performed in children have been mixed, but this study offers data to support repeat administration of PCN to this group of adults. However, the criteria for PCN allergy in this study are based solely on participant history and this suboptimal case definition may result in a study population that includes those whose prior reactions were not IgE-mediated. Should that be the case, the number of participants who became resensitized could be falsely low. Ultimately, the risk of PCN resensitization should be studied in those for whom there is documentation of both a clinical reaction and IgE to PCN.