Direct oral amoxicillin challenge without preliminary skin testing in adult patients with allergy and at low risk with reported penicillin allergy

Introduction:

Ten percent of hospitalized patients report penicillin allergy; however, recent studies indicate that ∼98% of these patients are not acutely hypersensitive. Unconfirmed penicillin allergy poses public health risks, and an evaluation of penicillin allergy labels is recommended to improve antibiotic stewardship. Although the most widely accepted protocol is penicillin skin testing, followed by oral amoxicillin challenge, time constraints and resources may preclude this. Recent literature supports the safety and efficacy of direct oral amoxicillin challenge in individuals at low risk.

Methods:

We retrospectively evaluated direct oral challenge acceptance and outcomes in eligible adult outpatients with allergy and with a penicillin allergy label over a 6-month period. Direct oral amoxicillin challenge was recommended in patients with a history of benign rash, benign somatic symptoms, or unknown history associated with the last penicillin exposure >12 months ago. Those with severe reactions or reactions within 12 months of evaluation were not challenged. The patients were monitored for 60 minutes after challenge and were discharged with instructions to call in the event of a delayed reaction.

Results:

There were 50 of 355 adults (14%) with a penicillin allergy label seen by a single allergist; of these patients, 38 (76%) met our criteria for a direct oral challenge. The index penicillin associated reactions were mostly remote, and 44 subjects (88%) reported reactions >10 years earlier. Four patients (8%) were de-labeled based on history alone. Twenty subjects (40%) consented to challenge in the clinic, and none developed immediate, or to our knowledge, delayed hypersensitivity reactions. Three of 20 patients (15%) developed self-limited subjective symptoms that were not deemed to constitute true immunoglobulin E mediated hypersensitivity. A total of 24 patients (48%) had the penicillin allergy label removed from their medical record.

Conclusion:

This study added to the accumulating body of evidence that supports the safety and efficacy of direct provocative challenge without preliminary skin testing to exclude penicillin allergy in individuals at low risk. Larger prospective studies are necessary to confirm these observations.