SKIN-TESTS IN THE DIAGNOSIS OF ERUPTIONS CAUSED BY BETA-LACTAMS

The aetiologic evaluation of adverse cutaneous reactions to penicillin s is still not an easy problem to solve. Skin testing is usually carri ed out intradermally with benzylpenicilloyl polylysine (BPO-PPL) and m inor determinant mixture (MDM), but these are often unsuitable for the detection of sensitivity to betalactam antibiotics. 101 selected subj ects, with different cutaneous reactions to betalactams and with a cli nical history of positive challenge, were skin tested (patch test, pri ck test, intradermal test) with a standard betalactam series (amoxycil lin, sodium penicillin G, ampicillin, bacampicillin, aztreonam, ceftri azone, BPO-PPL, MDM). 1 or more positive reactions to skin tests, main ly to intradermal tests, were observed in 47.5% of the subjects studie d, especially in those with maculopapular eruptions, urticaria/angioed ema and drug reactions caused by ampicillin and amoxycillin. Cross-sen sitivity was demonstrated in 22.8% of cases and was due almost solely to the semisynthetic penicillins. Finally, to increase the yield in de tecting positive patients, it is necessary that ampicillin and amoxyci llin be tested in addition to major and minor determinants. (C) Munksg aard, 1997.