Indications

Bacitracin is a topical antibiotic ointment widely used by both medical professionals and the general public to treat minor skin injuries including cuts, scrapes, and burns.

Bacitracin was discovered in 1945 from a leg injury of a seven-year-old American girl named Margaret Tracey. The collected debris from her wound grew isolates of several related cyclic polypeptides produced by a member of the Bacillus subtilis group. This discovery gave rise to the unique name, bacitracin.[1] 

The United States Food and Drug Administration (FDA) approved the use of bacitracin in 1948 for the short-term prevention and treatment of both acute and chronic localized skin infections. Less frequently, bacitracin can also be given as a parental medication via intramuscular (IM) injection for the systemic treatment of infantile streptococcal pneumonia and empyema. To date, there are no record of any non-FDA approved uses of topical bacitracin.

Bacitracin can be used as a single agent ointment or in combination as a triple therapy ointment, with neomycin and polymyxin B. The latter can be found over the counter (OTC) at local pharmacies.[2] 

Mechanism of Action

Bacitracin is a mixture of several closely related cyclic polypeptide antibiotics that has both bacteriostatic and bactericidal properties depending on the concentration of the drug and the susceptibility of the microorganism. 

Many gram-positive bacteria including Staphylococcus spp., Streptococcus spp., Corynebacterium spp., Clostridium spp., and Actinomyces spp. are susceptible to bacitracin. Some gram-negative organisms, such as Neisseria spp. also exhibit susceptibility; however, most gram-negative organisms are resistant.[3]

Bacitracin readily absorbs through denuded, burned, or granulated skin and works to prevent the transfer of mucopeptides into the cell wall of various microorganisms. This subsequently inhibits bacterial cell wall synthesis and ultimately, bacterial replication. Bacitracin also acts as an inhibitor of proteases and other enzymes involved in altering bacterial cell membrane function. Bacitracin inhibits bacterial cell wall synthesis by preventing the dephosphorylation of P-P-phospholipid carrier that attaches the cell wall peptidoglycan precursor units to the cell membrane, and this leads to bacterial cell lysis.[4]

Administration

Bacitracin is available in three different routes of administration in the USA: topical, ophthalmic, parenteral via IM injection. 

Its most common use is as a topical agent that is administered directly onto the wound or infected area. It can also be administered as a topical ophthalmic ointment to treat superficial ocular infections involving the conjunctiva and cornea.[5] 

Before topical application, the skin should be cleansed gently with mild soap and water. Enough ointment should then be applied to cover the affected area(s), and a sterile dressing can be used to cover the wound. This helps to assist in wound healing and prevent further contamination of the wound site. 

Adverse Effects

When used topically as a single agent ointment or part of a triple therapy ointment, bacitracin, and its drug formulation components may cause allergic contact dermatitis which could lead to an anaphylactoid reaction or anaphylaxis.[6]

Common and mild side effects of the topical use of bacitracin include[2][7]

• Fever
• Hives
• Itching
• Swelling of lips and face
• Difficulty breathing
• Nausea
• Vomiting

Pregnancy[8]

• Bacitracin is a pregnancy risk category C.
• No large studies have been conducted with the use of topical bacitracin during pregnancy or lactation.
• To date, there is no evidence to suggest that there is an increased risk of adverse fetal development with the use of topical bacitracin. 

Breast-Feeding[9]

• Topical and ophthalmic forms of bacitracin typically result in minimal absorption through the skin and are considered a low risk to the feeding infant.
• Only water-soluble creams or gel products should be applied to the breast tissue to prevent infant exposure to mineral paraffin from licking.

Contraindications

Topical bacitracin is contraindicated in anyone with hypersensitivity to bacitracin and/or any of its drug formulation components. Patients with known hypersensitivity to neomycin may also be sensitive to bacitracin.

Bacitracin application on an infection or wound that is caused by a viral or fungal infection may increase the risk for the development of drug-resistant bacteria.  

Topical bacitracin use is recommended only for minor skin injuries and should not be used over larger areas of the body.

Physician consultation is recommended before using topical bacitracin for serious injuries such as burns, deep wounds, puncture wounds, or animal bites.[10][11]

Monitoring

Secondary infections may develop; therefore, topical bacitracin should not be used for more than seven days unless directed by a physician. The area of application should undergo monitoring for improvement. Bacitracin use should be stopped immediately if symptoms worsen and a physician should be contacted regarding further management.

Allergy patch testing may be warranted if an adverse reaction occurs after the use of bacitracin as a single agent ointment or part of a triple therapy ointment. There have been multiple reports of anaphylactoid reactions and anaphylaxis due to bacitracin use.[6][12][13]

Toxicity

There is no mention of toxicity with the topical use of bacitracin as a single agent ointment or part of a triple therapy ointment.

However, the IM route has been shown to cause nephrotoxicity and renal failure due to tubular and glomerular necrosis. Consequently, careful monitoring is in order with the IM use of bacitracin. Renal function should be determined before, during, and after IM administration. Patients' daily optimal fluid intake and urinary output should be followed closely to avoid kidney injury. 

Concurrent use of streptomycin, kanamycin, polymyxin E, and neomycin should be avoided as these drugs are also known to be nephrotoxic.[14][15]

Enhancing Healthcare Team Outcomes

Topical bacitracin has been easily accessible and considered a safe OTC topical antibiotic for the past seven decades. Despite its effectiveness, increases in use and adverse effects led to it earning, in 2003, the undesirable designation “contact allergen of the year” by the American Contact Dermatitis Society. In 2005-2006, it was also ranked the sixth most prevalent allergen in patch tests.[2][16][17][18]

As a result, all healthcare professionals should be aware of the potential risks of an anaphylactoid reaction or anaphylaxis secondary to bacitracin use. Anyone with confirmed contact dermatitis should avoid products containing bacitracin. Providers should encourage their patients to read the labels for bacitracin in ointments, creams, and other wound care products.

Providers should make a habit of inquiring about bacitracin use when encountering a patient with a possible contact allergy or unremitting dermatitis or non-healing wound as bacitracin allergy may present as cellulitis or simple wound infection. One clinical clue to decipher an allergic reaction from an infectious process is the presence of itching instead of worsening pain, respectively. (Level III)

Bacitracin should be used cautiously in patients with pre-existing renal impairment or renal failure. To ensure patient safety, physicians, nurses, and pharmacists, et al.. should work as a team to monitor patients' intake, urinary output, and renal function. Due to the significant risk of nephrotoxicity, pharmacists should provide alternative medication options when available. 

Bacitracin is also present in some veterinary products, and pet owners should also be highly cautious when applying topical bacitracin medications.