Allergy and Clinical Immunology

Background: Ten percent (10%) of hospitalized patients report Penicillin Allergy (PA); however, studies indicate that ~98% patients are not truly allergic. Unconfirmed PA labels pose substantial public health risks and PA evaluation is recommended as part of effective antibiotic stewardship. While the most widely accepted protocol is Skin Testing (ST) followed by oral

amoxicillin challenge, time constraints and other limited resources may be a barrier to ST application. An accumulating body of evidence supports the safety and efficacy of using direct oral amoxicillin challenges in low-risk individuals with a history of PA.

Objectives: To evaluate the safety of direct oral graded challenges to amoxicillin.

Methodology: This is a retrospective review of adult patients treated at the outpatient allergy clinic at Emory University. For PA, we currently recommend direct oral amoxicillin challenge in patients with history of benign rash, benign somatic symptoms or unknown history associated with last penicillin exposure >12 months ago. If the index reaction occurred within the past 12 months, or with a history of anaphylaxis, we perform ST first and proceed to oral challenge only if the ST is negative. We do not evaluate PA further if there is a history of a penicillin-associated blistering rash, hemolytic anemia or organ involvement. Any delayed reactions after the oral challenge are reported by the patient.

Results: We describe outcomes of direct oral challenges in patients with PA labels. No acute positive reactions or delayed reactions were noted for the course of the study period. While subjective reactions were reported, these did not constitute a clinically significant challenge reaction.

Conclusion: Direct oral challenge without preceding ST is safe and sufficient to rule out PA in low risk patients. While a history of anaphylaxis or severe drug reactions warrants extreme caution, a simpler and more streamlined protocol might do for lower risk patients.