Background:

Bacitracin is widely used for the treatment and prevention of superficial skin infections. Although commonly used, anaphylaxis to topically applied bacitracin is rare, with only nine previously reported cases. Most reported reactions have occurred in middle-aged to elderly women with leg ulcers or chronic eczema. Although most reports include a challenge test to confirm the diagnosis, no recommended standardized method of skin testing for bacitracin anaphylaxis has been advocated to date.

Objective:

We report two patients who developed anaphylaxis to topically applied bacitracin ointment confirmed by skin prick testing. The subject of bacitracin anaphylaxis is reviewed, and a method for confirmatory skin testing is recommended.

Methods:

Literature was searched in the MEDLINE database using the key words anaphylaxis and bacitracin, and articles from the American Journal of Contact Dermatitis were also included. Relevant references from these reports were also reviewed. Percutaneous skin prick testing was performed on our 2 patients using the bacitracin powder dilution (10 U/mL and 1 U/mL). Normal control individuals were also tested.

Results:

Two patients with anaphylaxis to bacitracin are reported. One developed symptoms after a biopsy of chronic eczema was performed. The second patient had no prior history of chronic skin disease and developed symptoms after incurring an abrasion on his knee. The diagnosis was confirmed by a positive wheal and flare reaction after skin prick testing at 1 U/mL and 10 U/mL concentrations, respectively. Normal controls showed no wheal and flare reaction at 10 U/mL.

Conclusions:

Anaphylaxis to topical bacitracin is rare but potentially fatal. Based on our literature review and the results of our skin testing, we recommend initiating future bacitracin prick testing with 0.1 U/mL. If no reaction occurs at this dilution, subsequent prick testing should be serially performed with a 10-fold higher concentration. Each test should be separated by 15 minutes to a maximum concentration of 10 U/mL. Testing at higher concentrations or by the intradermal method may lead to a false-positive test. This is a US government work. There are no restrictions on its use.

Search results

A Composite Model for Multiple Assays of Skin Irritation

Anaphylaxis to Topically Applied Bacitracin