Positive drug provocation with beta-lactam antibiotics in children: A single test may not be enough.

Background: Drug provocation tests (DPTs) are considered the gold standard for diagnosing beta-lactam allergy. However, positive results tend to be mild and difficult to interpret. This study aimed to describe pediatric patients with a presumedly positive or inconclusive DPT, assess the decision to repeat the DPT, and describe its outcome.

Methods: Retrospective review of all presumedly positive or inconclusive DPTs performed in six pediatric allergy clinics from 2017 to 2019. We describe the interpretation of results, focusing on the decision to repeat the DPT and its outcome.

Results: Of 439 children challenged with a beta-lactam, 26 (5.9%) with a presumedly positive or inconclusive result were included in this study. Most were girls (n = 16, 61.5%), and the median age was 5 years (range 1-13). The initial DPT used amoxicillin (n = 13, 50.0%), amoxicillin-clavulanic acid (n = 12, 46.2%), or cefadroxil (n = 1, 3.8%). Reactions were early (n = 11, 42.3 %), delayed (n = 14, 53.8 %), or not registered (n = 1, 3.8 %), but mild in all cases. A second confirmatory DPT was proposed in 19 patients (73.1%) and performed in 17 patients (65.4%). Nine DPTs were performed from 1 day to 4 months after the first DPT, and the remaining eight took place 6 months to 2 years later. Fifteen children tolerated the drug in the second DPT: 88.2% of those reevaluated and 57.5% of the whole study group.

Conclusion: The positive predictive value of DPT may be lower than expected. Given the mildness of observed reactions, a second confirmatory DPT is warranted within a few weeks or months.