Localized pustulosis induced by betalactams

Localized forms of pustular drug eruptions related to antibiotics are uncom mon and their mechanism is still unknown. We describe herein a patient who developed numerous pinhead pustules without erythema in the peribuccal area after ingestion of ceftibuten and amoxicillin. The relationship with these drugs was confirmed by single-blind oral challenges. The following tests w ere performed: prick and intradermal tests with benzylpenicilloyl polylysin e, minor determinant mixture. benzylpenicillin and amoxicillin: patch tests were also carried out with benzylpenicillin, amoxicillin, cloxacillin, cef uroxime, ceftriaxone, cefazolin, ceftibuten and cefaclor. All cutaneous tes ts were negative. Controlled single-blind challenge tests were performed wi th amoxicillin, cefadroxil, ceftibuten, cefuroxime, cefaclor, erythromycin and ciprofloxacin. All betalactam antibiotics tested gave a positive reacti on, with good tolerance of other antibiotics, this would appear to indicate a specific mechanism of hypersensitivity and not an unspecific reaction to wide spectrum antibiotics.