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.
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.
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.
Allergic reactions to polymyxin B are not rare, and this antibiotic warrants inclusion in the standard patch testing series.
From the Division of Dermatology, McGill University Health Centre, Montreal, Quebec, Canada.
Address reprint requests to Denis Sasseville, MD, FRCPC, McGill University Health Centre, Montreal General Hospital, Room L8.201, 1650 Cedar Ave, Montreal, Quebec, Canada H3G 1A4. E-mail: firstname.lastname@example.org.
Denis Sasseville receives royalties from UpToDate (Wolters Kluwer Health).
The other authors have no funding or conflicts of interest to declare.