2 CASES OF TOXIC EPIDERMAL NECROLYSIS CAUSED BY DELAYED-HYPERSENSITIVITY TO BETA-LACTAM ANTIBIOTICS

The authors describe two cases of toxic epidermal necrolysis (TEN) cau sed by delayed hypersensitivity to semisynthetic penicillins. The firs t patient developed erythema of the lower limbs following an im. injec tion of ampicillin, which progressed to TEN as therapy was continued. Fever and eosinophilic leukocytosis were also present. In the second c ase, TEN developed following oral amoxicillin therapy, and was precede d by a diffuse, maculopapular eruption. In both cases, symptoms resolv ed with the prompt administration of steroids. Both patients underwent allergological testing: prick test and, if results were negative, int radermal tests with penicilloyl-polylysine (PPL), minor determinant mi xture (MDM), penicillin, amoxicillin and ampicillin. Patch testing wit h penicillin, ampicillin and amoxicillin was also performed. Both pati ents developed positive reactions to the intradermal tests after 6 h, and to patch tests after 48-72 h (for ampicillin, amoxicillin and peni cillin in the first case, and for ampicillin and amoxicillin in the se cond). The lymphocyte transformation test (LTT), performed only in the first case, was positive for ampicillin. As these cases demonstrate, delayed hypersensitivity should be suspected in cases of drug-related TEN Patch testing is a simple and useful allergological test for these types of cases.