Population-Based Incidence of New Ampicillin, Cephalexin, Cefaclor, and Sulfonamide Antibiotic Allergies in Exposed Individuals with and without Preexisting Ampicillin, Cephalexin, or Cefaclor Allergies

BACKGROUND: There is a theoretical concern, unconfirmed by population-based challenge data, that clinically significant, immunologically mediated hypersensitivity occurs among b-lactams sharing side chains. OBJECTIVE: To determine the population-based allergy incidence associated with the use of b-lactams sharing exact R1 side chains (ampicillin, cephalexin, and cefaclor [ACC]), with or without a current ACC allergy or a sulfonamide antibiotic allergy for comparison. METHODS: All courses of ACC and trimethoprimsulfamethoxazole used by any Kaiser Permanente California members in 2017 and 2018, with follow-up through January

Automated summary

This study aimed to investigate the association between the use of b-lactams sharing exact R1 side chains and allergic reactions. The research tracked all courses of ACC and trimethoprimsulfamethoxazole used by Kaiser Permanente California members in 2017 and 2018, comparing with sulfonamide antibiotic allergy.