Cross reactivity of cephalosporins with penicillin.

Cross antigenicity of cephalosporins with penicillin has been studied experimentally and also by using serum from penicillin sensitive individuals. Definite hypersensitivity reaction was observed in all the animals sensitised with cephalosporins and challenged with penicillin except in rats. Cephalosporins could elicit reaction in tissues sensitised passively with serum obtained from penicillin sensitive individuals.