Bacitracin: A unique topical antibiotic sensitizer

Topical bacitracin appears to be unique for the following reasons: (1) It is becoming a frequent sensitizer, particularly when used after surgery. (2) It may cause not only a delayed, eczematous contact dermatitis but an immediate urticarial reaction and, rarely, anaphylactic shock. (3) Positive patch test reactions to bacitracin often do not appear at the usual 48-hour test reading but may be positive when read at 96 hours. (4) Zinc bacitracin and “plain” bacitracin are two forms of topical bacitracin available, with possibly different degrees of sensitizing potential. (5) Bacitracin injected intradermally has been reported to be a histamine-releasing agent. (6) Bacitracin often coreacts but does not cross-react with neomycin. In this presentation we document the clinical and patch test findings of nine patients seen in the past year with allergic contact dermatitis to bacitracin ointment.