title: Contact Allergy to Polymyxin B Among Patients Referred for Patch Testing.
abstract: BACKGROUND
  Polymyxin B is not included in most standard contact allergen series. The aim of this study was to determine the prevalence of contact sensitization to polymyxin B in a population of patients referred for patch testing.
  
  
  METHODS
  A retrospective cohort study design was used to collect data on 795 patients referred to the contact dermatitis clinic of the McGill University Health Centre, as well as to the office of one of the authors (L.M.), between March 2014 and November 2015. Patients were patch tested to the North American Contact Dermatitis Group baseline series and polymyxin B sulfate 3% in petrolatum.
  
  
  RESULTS
  Out of 795 tested individuals, 18 were allergic to polymyxin B, for a prevalence of 2.3%. The eruptions affected almost all body parts, but mostly the face. The degree of reaction ranged from 1+ to 2+. Isolated reactions to polymyxin B occurred in 9 (50%) patients, whereas reactions to bacitracin and polymyxin B were seen in the other 9. Only 1 patient reacted to bacitracin, polymyxin B, and neomycin (11.1%). Most reactions (12/18) were from past exposure to polymyxin B.
  
  
  CONCLUSIONS
  Allergic reactions to polymyxin B are not rare, and this antibiotic warrants inclusion in the standard patch testing series.
authors.affiliation: From the Division of Dermatology, McGill University Health Centre, Montreal, Quebec, Canada.
authors.forename: Maisa
authors.initials: M
authors.lastname: Alfalah
authors.forename: Hanieh
authors.initials: H
authors.lastname: Zargham
authors.forename: Linda
authors.initials: L
authors.lastname: Moreau
authors.forename: Monica
authors.initials: M
authors.lastname: Stanciu
authors.forename: Denis
authors.initials: D
authors.lastname: Sasseville
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011112:Polymyxin B / Q000009:adverse effects*; D015995:Prevalence; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents; D011112:Polymyxin B