We investigated 16 patients with macular or maculopapular rashes to aminope
nicillins using an identical test protocol. 5 of these 16 subjects presente
d delayed hypersensitivity to ampicillin and also to amoxycillin in skin te
sting (patch test, prick- and intradermal test with reading late reactions)
. In 3 cases challenge to penicillin G and V was possible and they were wel
l tolerated. Therefore we consider a side-chain-allergy specific to aminope
nicillins.