Contact sensitivity to topical antimicrobials

A predictive study comparing the sensitizing potentials of some topical antimicrobials, using a modified Beuhler's technique, showed that over‐the‐counter (OTC) antimicrobials were more sensitizing than prescribed topical antibiotics, Among OTC antimicrobials, proflavine was the most potent sensitizer (4/10 guinea pigs); parachlorometaxylenol, benzalkonium chloride and propamidine isethionate moderate sensitizers (2/10 guinea pigs); iodine a weak sensitizer (1/10 guinea pigs); and chlorhexidine and cetrimide very weak sensitizer (0/10) guinea pigs). Among prescribed topical antibiotics, ncomycin was a moderate sensitizer (2/10 guinea pigs); gentamycin and chloramphenicol weak sensitizers (1/10 guinea pigs); kanamycin, clioqunol, polymyxin B, bacitracin, tetracycline, sodium fusidate and fusidic acid very weak sensitizers (0/10 guinea pigs), There was good correlation between sensitizing potentials in animal studies and clinical experience of contact allergy to these topical antimicrobials.