NONIMMEDIATE REACTIONS TO BETA-LACTAMS - PREVALENCE AND ROLE OF THE DIFFERENT PENICILLINS

In patients treated with penicillins, adverse cutaneous reactions can occur within minutes or may take several days to develop. IgE antibody -mediated reactions are well documented, but other mechanisms may also be involved. In particular, nonimmediate reactions have not been stud ied extensively, and the purpose of the present work was to establish the incidence of such reactions among a large group of patients and to study the penicillins involved. A total of 380 subjects with a histor y of a cutaneous reaction following administration of a penicillin ant ibiotic was included in the study. Skin tests and specific IgE measure ments (RAST) were carried out using various penicillins and penicillin -related reagents, and patients were also challenged with various peni cillins. In some patients with delayed skin test responses, skin biops ies were carried out. The tests confirmed that 74 subjects (19.4% of t otal investigated) had suffered a cutaneous reaction to a penicillin d erivative, and 29 of these subjects (7.6% of total or 39% of confirmed ) showed evidence of having suffered a nonimmediate reaction. The latt er group were identified by giving a positive delayed direct challenge , and in 65% of the cases a delayed skin test response was detected. I n most cases, these responses were to amino penicillins. Skin biopsies showed a lymphomonocytic cell infiltrate. Nonimmediate reactions to p enicillins are a reproducible phenomenon, suggesting that a specific m echanism is responsible. By direct challenge, 93% of responders were p ositive to amino penicillins (10.3% ampicillin, 82.7% amoxicillin), in dicating a major role for these penicillins in nonimmediate reactions. The high percentage (65%) of subjects in this group who showed delaye d skin test responses, taken together with the biopsy results, suggest s that a lymphocyte-mediated reaction occurred. However, the possibili ty that other mechanisms may also have been involved cannot be ruled o ut.