Positive patch test reactions to gentamicin show sensitization to aminoglycosides from topical therapies, bone cements, and from systemic medication

Background: A history of prolonged use of topical antimicrobials is common among patients with positive patch test reactions to gentamicin and to aminoglycosides. Objectives: The aim of this study was to show sources of gentamicin sensitization in patients with positive patch test reactions to gentamicin. Patients and methods: About 7814 patients were patch tested with a baseline patch test series and 620 of them were further tested with gentamicin. The clinical histories, concurrent contact sensitivities, and sources of sensitization are analysed among these patients. Results: Positive patch test reactions to gentamicin were seen in 29/620 patients, most of whom (18/29) also reacted to neomycin and to kanamycin (7/29). Mean age of the gentamicin‐positive patients was 62 years, but three young operating room nurses with hand dermatitis had a history of gentamicin exposure from bone cement. Among the 11/29 neomycin‐negative patients, a history of exposure to different aminoglycosides was apparent, and one patient had a history of systemic netilmicin‐medication‐associated exanthema. Conclusions: Positive patch test reactions to gentamicin reflect sensitization to different aminoglycosides for which gentamicin seems to represent a sensitive indicator. Gentamicin sensitization may result from occupational exposure to gentamicin containing bone cements or from systemic medication with aminoglycosides.