D3.34 - Cephalosporine drug provocation in a population of children with confirmed serum sickness-like reaction to amoxicillin

Non-immediate drug reactions are frequently observed with the use of β-lactams in children. Recent guidelines recommend that primary physicians challenge these patients if no severe symptoms are reported with the rash. However, serum sickness-like reaction (SSLR), characterized by the presence of a non-immediate rash associated with articular symptoms, is not targeted by these recommendations. Even though few studies have explored the risk of allergy due to prolonged amoxicillin re-exposure, estimated between 10-25%, the risk of allergic cross-reaction to cephalosporins in this population is unknown.

This was a retrospective study using patient records of those who underwent a prolonged amoxicillin drug provocation test (DPT) in the context of a previous SSLR during a β-lactam exposure. Data were collected using an Excel file, and descriptive analysis was conducted using medians and percentages.

Between October 2021 and November 2024, 42 children underwent prolonged amoxicillin DPT in the context of a previous SSLR. Fifty-two percent were male, and the average age was 2 years. The delay between the reaction and the DPT was an average of ten months. Forty-two children underwent prolonged amoxicillin DPT, which was positive in sixteen cases (38%). Of these, a non-immediate rash was reported for all children and articular symptoms in six cases (38%). Cefprozil prolonged DPT was then performed in twelve children (75%) with positive amoxicillin DPT results. Two children (17%) had positive DPT results. Both had non-immediate rash, and one had articular symptoms. No anaphylactic reaction or DPT complications were reported in these patients.

This study shows that prolonged amoxicillin and cefprozil DPT seem safe and useful to avoid falsely labeling patients with β-lactam allergy.