Food anaphylaxis to bovine serum albumin

Abstract

Although rare, anaphylaxis has been reported after topical administration of bacitracin ointment.1-7 All reported patients, including ours, had applied the drug to a compromised skin barrier (i.e., leg ulcers, excoriated dermatitis, or burns). Thus ready access to the systemic circulation seems to be a prerequisite for the development of anaphylaxis from this externally applied agent. The severity of reported anaphylaxis to bacitracin is particularly noteworthy, with hypotension documented in six of eight cases.1-4, 6 Four of eight reported cases demonstrated the presence of IgE to bacitracin, two by direct skin testing1, 5 and two by PK testing.2, 4 Given his near-fatal reaction, our patient declined to be skin tested. Immunoassay results for IgE antibody and basophil histamine release test results were negative. However, without a positive control, these negative in vitro assays do not exclude the presence of IgE antibody to bacitracin. Bacitracin, a low molecular weight polypeptide, may have to act as a hapten, and a protein carrier is not present in these in vitro systems. Furthermore, bacitracin is labile in aqueous solution, which may also have led to the negative in vitro assay results. Therefore PK testing on a rhesus monkey was pursued. The passive transfer of immediate-type hypersensitivity between heterologous species has been described by using human serum in rhesus monkeys.8 Serum from our patient, as well as from one of the reported cases, caused positive PK test results in monkeys, thus confirming the presence of IgE antibody to bacitracin. We report this case of anaphylaxis after the topical administration of bacitracin so that physicians may be aware of this rare, but potentially life-threatening, reaction to a commonly used medication.