Bacitracin - Drug Monograph

Introduction

Bacitracin is a polypeptide antibiotic derived from Bacillus subtilis that has been in clinical use since the 1940s. It is primarily used topically due to its nephrotoxic potential when administered systemically. Bacitracin demonstrates bactericidal activity against a wide spectrum of Gram-positive organisms and some Gram-negative bacteria, making it a valuable agent in dermatologic and ophthalmic preparations.

Mechanism of Action

Bacitracin exerts its bactericidal effect by interfering with bacterial cell wall synthesis. Specifically, it inhibits the dephosphorylation of the lipid carrier (undecaprenyl pyrophosphate) that transports peptidoglycan precursors across the cytoplasmic membrane. This disruption prevents the regeneration of the lipid carrier molecule, effectively halting the incorporation of new units into the peptidoglycan cell wall. The resulting structural weakness leads to osmotic instability and eventual bacterial cell death.

Indications

• Topical treatment of superficial skin infections caused by susceptible organisms
• Prophylaxis of minor skin abrasions, cuts, and burns
• Ophthalmic infections (in combination with other antibiotics)

• Nasal decolonization of Staphylococcus aureus (often in combination with mupirocin)
• Treatment of superficial ocular infections
• Component of triple antibiotic ointments (with neomycin and polymyxin B)

Dosage and Administration

• Apply a thin layer to affected area 1-3 times daily
• Cover with sterile bandage if desired
• Duration: Typically 7-10 days or until healing occurs

• Instill ½ inch ribbon into conjunctival sac every 3-4 hours
• For severe infections: May be used every 2 hours

• Renal impairment: Use with caution systemically (not recommended); no dosage adjustment needed for topical use
• Hepatic impairment: No dosage adjustment required
• Pediatrics: Safe for use in children; apply sparingly
• Geriatrics: No specific dosage adjustments

Pharmacokinetics

Contraindications

• Hypersensitivity to bacitracin or any component of the formulation
• History of anaphylactic reactions to bacitracin
• Use in extensive burns or large open wounds (due to increased systemic absorption risk)

Warnings and Precautions

• Nephrotoxicity: Systemic administration may cause severe renal damage
• Allergic reactions: Contact dermatitis may occur with prolonged use
• Superinfection: Prolonged use may result in fungal or bacterial resistance
• Ophthalmic use: May delay corneal healing; not for use in deep ocular infections or corneal ulcers
• Pregnancy: Category C - Use only if potential benefit justifies potential risk
• Lactation: Exercise caution; unknown if excreted in human milk

Drug Interactions

• Neuromuscular blocking agents: Bacitracin may enhance neuromuscular blockade
• Other nephrotoxic drugs: Increased risk of renal toxicity when used systemically (aminoglycosides, amphotericin B, cisplatin)
• Topical corticosteroids: May mask signs of infection or allergic reaction

Adverse Effects

• Local irritation
• Contact dermatitis
• Pruritus
• Skin rash

• Anaphylaxis (rare)
• Nephrotoxicity (with systemic use or extensive topical application)
• Severe allergic reactions including angioedema
• Ocular toxicity (with ophthalmic use)

Monitoring Parameters

• Topical use: Monitor for signs of hypersensitivity, superinfection, and healing progress
• Systemic use (if applicable): Renal function tests (BUN, creatinine), urine output
• Ophthalmic use: Corneal integrity, visual acuity, signs of irritation
• Long-term use: Signs of bacterial resistance or fungal overgrowth

Patient Education

• Use only as directed by healthcare provider
• Clean affected area before application
• Apply thin layer; excessive use does not improve efficacy
• Discontinue use and contact healthcare provider if:

- Condition worsens or doesn't improve within 7 days - Signs of allergic reaction appear (rash, itching, swelling) - Signs of infection increase (redness, pus, pain) - For ophthalmic use: vision changes or eye pain occurs

• Do not use on deep wounds, puncture wounds, animal bites, or serious burns without medical supervision
• Keep out of reach of children
• Store at room temperature away from moisture

References

1. Lexicomp Online. Bacitracin: Drug Information. Wolters Kluwer Clinical Drug Information, Inc. 2023. 2. Micromedex Solutions. Bacitracin Detailed Drug Information. IBM Watson Health. 2023. 3. Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman's: The Pharmacological Basis of Therapeutics. 13th ed. McGraw-Hill Education; 2017. 4. FDA Prescribing Information: Bacitracin Ointment. Accessed October 2023. 5. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):147-159. 6. American Academy of Ophthalmology. Preferred Practice Pattern: Bacterial Keratitis. 2018. 7. Zeller VA, Letertre MP, Dingeon B, et al. Evaluation of bacitracin and neomycin as possible markers of exposure to antibiotics in animals for the monitoring of meat and milk. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2018;35(5):887-899.