CROSS-REACTIONS BETWEEN TOPICALLY USED AM INOGLYCOSIDE ANTIBIOTICS

The frequency of cross reactions between the aminoglycoside antibiotic s neomycin, framycetin, gentamicin and kanamycin and the peptide antib iotic bacitracin is analyzed in patch test data of the ''Informationsv erbund Dermatologischer Kliniken'' (IVDK) from 1990 to 1993. Cross rea ctions between neomycin and framycetin were seen in about 70%. Therefo re, testing neomycin as an indicator for a contact allergy to framycet in would yield false negative results in about 30% of the cases. Simul taneous reactions to neomycin and gentamicin were observed in nearly 4 0% of the patients allergic to neomycin and nearly 50% of those allerg ic to gentamicin. Similar proportions were seen in Finland 20 years ag o, indicating a real cross sensitization to these different antibiotic s. About 80% of the patients allergic to kanamycin also reacted to neo mycin, however, vice versa this frequency was only 46%. About 47% of t hose allergic to gentamicin showed a reaction to kanamycin and about 6 2% of the patients allergic to kanamycin showed a reaction to gentamic in. Obviously, more patients become primarily sensitized to gentamicin than to kanamycin, which can be explained by the more frequent use of gentamicin in topical preparations in Germany. Concomitant in topical preparations in Germany. Concomitant sensitizations to neomycin and b acitracin were seen by far less frequently than in Finland in the 1960 s (ca. 15% vs. 77%).