Randomized Multicenter Trial for the Validation of an Easy-to-Administer Algorithm to Define Penicillin Allergy Status in Sexually Transmitted Infection Clinic Outpatients

Background: Approximately 15% of patients in sexually transmitted infection (STI) clinics report penicillin allergies, complicating treatment for syphilis and gonorrhea. Nonetheless, >90% do not have a penicillin allergy when evaluated. We developed and validated an algorithm to define which patients reporting penicillin allergy can be safely treated at STI clinics with these drugs.

Methods: Randomized controlled trial to assess feasibility and safety of penicillin allergy evaluations in STI clinics. Participants with reported penicillin allergy answered an expert-developed questionnaire to stratify risk. Low-risk participants underwent penicillin skin testing (PST) followed by amoxicillin 250 mg challenge or a graded oral challenge (GOC)-amoxicillin 25 mg followed by 250 mg. Reactions were recorded, and participant/provider surveys were conducted.

Results: Of 284 participants, 72 (25.3%) were deemed high risk and were excluded. Of 206 low-risk participants, 102 (49.5%) underwent PST without reactions and 3 (3%) had mild reactions during the oral challenge. Of 104 (50.5%) participants in the GOC, 95 (91.3%) completed challenges without reaction, 4 (4.2%) had mild symptoms after 25 mg, and 4 (4.2%) after 250-mg doses. Overall, 195 participants (94.7%) successfully completed the study and 11 (5.3%) experienced mild symptoms. Of 14 providers, 12 (85.7%) completed surveys and 11 (93%) agreed on the safety/effectiveness of penicillin allergy assessment in STI clinics.

Conclusions: An easy-to-administer risk-assessment questionnaire can safely identify patients for penicillin allergy evaluation in STI clinics by PST or GOC, with GOC showing operational feasibility. Using this approach, 67% of participants with reported penicillin allergy could safely receive first-line treatments for gonorrhea or syphilis. Clinical Trials Registration. Clinicaltrials.gov (NCT04620746).