Predominant patterns of ß-lactam hypersensitivity in a single German Allergy Center: exanthem induced by aminopenicillins, anaphylaxis by cephalosporins.

BACKGROUND: Penicillins and other ß-lactam antibiotics are the most common elicitors of allergic drug reaction. However, data on the pattern of clinical reaction types elicited by specific ß-lactams are scarce and inconsistent. We aimed to determine patterns of ß-latam allergy, i.e. the association of a clinical reaction type with a specific ß-lactam antibiotic. METHODS: We retrospectively evaluated data from 800 consecutive patients with suspected ß-lactam hypersensitivity over a period of 11 years in a single German Allergy Center. RESULTS: ß-lactam hypersensitivity was definitely excluded in 595 patients, immediate-type (presumably IgE-mediated) hypersensitivity was diagnosed in 70 and delayed-type hypersensitivity in 135 cases. Most (59 out of 70, 84.3%) immediate-type anaphylactic reactions were induced by a limited number of cephalosporins. Delayed reactions were regularly caused by an aminopenicillin (127 out of 135, 94.1%) and usually manifested as a measles-like exanthem (117 out of 135, 86.7%). Intradermal testing proved to be the most useful method for diagnosing ß-lactam allergy, but prick testing was already positive in 24 out of 70 patients with immediate-type hypersensitivity (34.3%). Patch testing in addition to intradermal testing did not provide additional information for the diagnosis of delayed-type hypersensitivity. Almost all ß-lactam allergic patients tolerated at least one, usually several alternative substances out of the ß-lactam group. CONCLUSIONS: We identified two patterns of ß-lactam hypersensitivity: aminopenicillin-induced exanthem and anaphylaxis triggered by certain cephalosporins. Intradermal skin testing was the most useful method to detect both IgE-mediated and delayed-type ß-lactam hypersensitivity.