title: Comparative frequency of patch test reactions to topical antibiotics.
abstract: BACKGROUND
  Neomycin, clioquinol and fusidic acid are all topical antibiotics widely used in dermatological practice in the U.K., either as a single agent or in combination with topical corticosteroids. However, an adverse effect of topical antibiotics is contact sensitization.
  
  
  OBJECTIVE
  To examine the frequency of positive patch test reactions to fusidic acid, clioquinol and neomycin.
  
  
  METHODS
  To compare the frequency of allergic patch test reactions over 1 year, we patch tested all patients attending the St John's Institute of Dermatology contact dermatitis clinic for one calendar year with fusidic acid, neomycin and clioquinol.
  
  
  RESULTS
  We patch tested 1119 patients. Positive patch test reactions to neomycin were noted in 40 patients (3.6%), compared with eight patients (0.7%) to clioquinol and three patients (0.3%) to fusidic acid. The frequency of medicament allergy to neomycin was thus five times more common than to clioquinol and ten times more common than to fusidic acid. Although fusidic acid is not part of our extended standard series, it is in our medicaments series. Therefore, in the second part of our study, we reviewed all cases of positive patch test reactions to fusidic acid over the last 20 years. We found that the frequency of hypersensitivity has decreased since the early 1980s despite increasing usage; the current average frequency being 1.62 patch-tested patients per year (1.45%) of those patch tested to the medicaments series). The most common diagnosis in such patients was stasis dermatitis (54.2%).
  
  
  CONCLUSIONS
  The frequency of fusidic acid allergy in an eczema population is low and is comparable with published data from over 10 years ago.
authors.affiliation: St John's Institute of Dermatology, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, UK. drsm@doctorsnet.co.uk
authors.forename: S D
authors.initials: SD
authors.lastname: Morris
authors.forename: R J G
authors.initials: RJ
authors.lastname: Rycroft
authors.forename: I R
authors.initials: IR
authors.lastname: White
authors.forename: S H
authors.initials: SH
authors.lastname: Wakelin
authors.forename: J P
authors.initials: JP
authors.lastname: McFadden
mesh_terms: D000287:Administration, Topical; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D007464:Clioquinol / Q000008:administration & dosage / Q000009:adverse effects*; D003877:Dermatitis, Contact / Q000209:etiology*; D003875:Drug Eruptions / Q000209:etiology*; D005260:Female; D005672:Fusidic Acid / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D008875:Middle Aged; D009355:Neomycin / Q000008:administration & dosage / Q000009:adverse effects*; D010328:Patch Tests / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D005672:Fusidic Acid; D007464:Clioquinol; D009355:Neomycin