Bacitracin is a polypeptide antibiotic that is chemically unrelated to neomycin. It inhibits bacterial cell wall synthesis. It is produced by Bacillus subtilis (Gehrig & Warshaw, 2008). Bacitracin is also a commonly used topical antibiotic (Jacob & James, 2004). It is available in both prescription and over-the-counter creams, ointments, and liquid vehicles. Bacitracin can cause nephrotoxicity and this is why it is used in a topical formulation only (Jacob & James, 2004). Like neomycin, bacitracin fights infections of the skin, ear, and eyes. It is active against gram-positive bacteria and spirochetes. It can be used alone or in combination with neomycin, polymyxin, and corticosteroids. During patch testing, bacitracin is tested at 20% concentration in petrolatum (Marks et al., 2002).
The frequency of ACD due to bacitracin has increased since 1980 (Marks et al., 2002). The incidence of bacitracin sensitivities have ranged from 1.5%-9.1% in the past 20 years in patch test patients (Gehrig & Warshaw, 2008). Nursing is the occupation with the highest frequency of ACD (Jacob & James, 2004). In 2003, the American Contact Dermatitis Society named bacitracin the Allergen of the Year.
Similar to neomycin, the risk of ACD caused by bacitracin increases if chronically used on diseased skin (Marks et al., 2002). However, bacitracin was found to be more common than neomycin in patients with venous insufficiency and leg ulcers (Gehrig & Warshaw, 2008; Rietschel & Fowler, 2008).
Bacitracin can cause localized eczema-like reactions. However, it can also cause type I, IgE-mediated hypersensitivity reactions, including contact urticaria and anaphylaxis (Gehrig & Warshaw, 2008; Marks et al., 2002). In fact, bacitracin is the most common topical antibiotic known to cause anaphylaxis. There have been 14 cases of bacitracin anaphylaxis reported from 1967–2002 (Jacob & James, 2004). To diagnose these conditions, a patient must undergo prick or scratch testing (Gehrig & Warshaw, 2008). When a patient's history suggests a type I reaction to bacitracin, the patient should be observed for a minimum of 1 hour after application of patches, with resuscitation equipment available (Gehrig & Warshaw, 2008).
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Cite this: Allergic Contact Dermatitis and Topical Antibiotics - Medscape - Sep 01, 2010.