A history of beta-lactam (BL) hypersensitivity is one of the most encountered problems in clinical practice and limits its further use. Determining whether patients with BL allergy could safely receive beta-lactams can be a difficult task. We summarize data from patients with a presumed allergic history to BL who underwent drug allergy verification and report the actual allergic rate.
Patients with a history of an immediate reaction or undetermined allergic onset to beta-lactams, who underwent BL hypersensitivity evaluation at King Chulalongkorn Memorial Hospital, Bangkok between 2012 and 2015, were retrospectively reviewed. The verification process was conducted according to the updated parameter on drug allergy included skin testing with both major and minor determinants of penicillin, amoxicillin, clavulanate, and/or the culprit BL. Intradermal test (IDT) was performed after negative skin prick test (SPT), and oral challenge test (OCT) was then carried out in patients who gave informed consent. Serum penicilloyl- and amoxycilloyl- specific IgE levels have also been evaluated.
A total of 86 patients (mean age 40.7 years) were included. Forty-eight patients (56%) were female and 42 patients (48.8%) had underlying medical illnesses. Most patients have allergic history to penicillin (45.4%) or amoxicillin (29.1%). Sixty percent of patients developed symptoms within 2 hours. The majority experienced skin symptoms; urticarial rash (24.3%), angioedema (21.4%), and maculopapular rash (20%), while 3 patients reported anaphylaxis. BL allergy was confirmed in 7 patients (8.1%); identified by positive skin tests in 2 patients, positive specific Ig-E levels in 3 patients, and positive OCT in 4 patients. For those with positive skin tests; one had positive SPT but negative Ig-E levels and another one had positive results for both IDT and specific Ig-E levels. Sixty patients (71.4%) were underwent OCT and 54 patients (90%) demonstrated negative challenge. Serum specific IgE levels were determined in 46 patients and 44 of them (95.7%) showed negative results. Mild non-immediate reactions developed in 4 patients upon OCT after negative skin tests.
The reliability of self-reported BL allergy is low and questionable. Skin tests and specific IgE determination are safe to diagnose patients with an immediate reaction to beta-lactams. Drug allergy de-labeling is needed to distinguish true allergic patients from non-allergic cases, particularly in certain circumstances when alternative antibiotics are not available nor appropriate.