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#118

Bacitracin

AntimicrobialBacitracin ZincBaciguent

A cyclic polypeptide antibiotic produced by Bacillus subtilis, widely used topically for prevention and treatment of minor skin infections and as a component of common first-aid ointments.

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Overview

Bacitracin is a mixture of cyclic polypeptide antibiotics produced by the bacterium Bacillus subtilis (originally isolated from a wound on a girl named Margaret Tracy in 1945, hence the name "baci-tracin"). It is one of the most widely used topical antibiotics worldwide, found in first-aid ointments either alone or in combination with other antibiotics such as neomycin and polymyxin B (as in Neosporin and Polysporin).

The mechanism of action involves inhibition of bacterial cell wall synthesis. Bacitracin specifically interferes with the dephosphorylation of C55-isoprenyl pyrophosphate (also called bactoprenol), a lipid carrier molecule essential for transporting cell wall building blocks (peptidoglycan precursors) across the bacterial cell membrane. By blocking this recycling step, bacitracin prevents the synthesis of new cell wall material, ultimately leading to bacterial cell death.

Bacitracin is primarily effective against Gram-positive bacteria, including Staphylococcus, Streptococcus, and Clostridium species. It has limited activity against Gram-negative organisms. Topical use is strongly preferred because systemic administration carries a significant risk of nephrotoxicity. The peptide is poorly absorbed through intact skin, which limits systemic exposure when applied topically and contributes to its favorable safety profile for over-the-counter use.

Beyond its primary role in topical first-aid, bacitracin has some specialized medical applications. It is used in ophthalmic ointments for eye infections, as an irrigating solution during surgery to prevent wound infections, and in laboratory settings as a reagent for identifying Group A Streptococcus (which is sensitive to bacitracin). Allergic contact dermatitis to bacitracin has been increasingly recognized and is now one of the more common causes of antibiotic-related contact allergy.

Research Uses & Applications

  • Topical prevention and treatment of minor skin infections (cuts, scrapes, burns)
  • Component of first-aid ointments (Neosporin, Polysporin) for wound care
  • Ophthalmic ointment for superficial bacterial eye infections
  • Surgical wound irrigation to prevent post-operative infections
  • Laboratory identification tool for Group A Streptococcus (bacitracin sensitivity test)
  • Intramuscular injection for infant pneumonia caused by susceptible staphylococci (rare, historical use)

Key Research Findings

  • Clinical studies support the efficacy of topical bacitracin in reducing infection rates in minor wounds when applied within the first few hours of injury.
  • Contact allergen surveillance data showed bacitracin is among the top 10 allergens in North American patch testing, with sensitization rates increasing over time.
  • In vitro studies confirmed potent activity against MRSA strains, though clinical relevance for topical treatment of MRSA skin infections remains debated.
  • Comparative studies showed triple antibiotic ointment (bacitracin/neomycin/polymyxin B) was not significantly superior to petroleum jelly alone for clean surgical wounds.
  • Research demonstrated that bacitracin resistance remains relatively uncommon among target Gram-positive pathogens despite decades of widespread use.

Risks & Side Effects

  • Allergic contact dermatitis is an increasingly recognized complication, sometimes severe.
  • Systemic use (injectable) carries significant nephrotoxicity risk and is rarely employed.
  • Rare cases of anaphylaxis have been reported with topical application, particularly to large open wounds.
  • Overuse may contribute to the selection of resistant organisms in the community setting.
  • Not effective against Gram-negative bacteria when used alone.

Administration

Applied topically to clean wounds 1-3 times daily as an ointment (typically 500 units/gram). Available as a single-agent ointment or in combination with neomycin and/or polymyxin B. Ophthalmic ointment applied to the lower conjunctival sac 1-3 times daily. Surgical irrigation uses solutions of 50-100 units/mL. Treatment duration for minor wounds is typically 7 days or until healed.

Legal Status

Available over-the-counter for topical use in the United States and many other countries. Prescription required for ophthalmic preparations. FDA-approved for topical wound care. Included on the WHO Model List of Essential Medicines.

Frequently Asked Questions

What is Bacitracin?

A cyclic polypeptide antibiotic produced by Bacillus subtilis, widely used topically for prevention and treatment of minor skin infections and as a component of common first-aid ointments.

What are the main uses of Bacitracin?

The primary research applications of Bacitracin include: Topical prevention and treatment of minor skin infections (cuts, scrapes, burns); Component of first-aid ointments (Neosporin, Polysporin) for wound care; Ophthalmic ointment for superficial bacterial eye infections; Surgical wound irrigation to prevent post-operative infections; Laboratory identification tool for Group A Streptococcus (bacitracin sensitivity test); Intramuscular injection for infant pneumonia caused by susceptible staphylococci (rare, historical use).

What are the risks and side effects of Bacitracin?

Documented risks and side effects include: Allergic contact dermatitis is an increasingly recognized complication, sometimes severe.; Systemic use (injectable) carries significant nephrotoxicity risk and is rarely employed.; Rare cases of anaphylaxis have been reported with topical application, particularly to large open wounds.; Overuse may contribute to the selection of resistant organisms in the community setting.; Not effective against Gram-negative bacteria when used alone.. Always consult a healthcare professional before considering any peptide.

Is Bacitracin legal?

Available over-the-counter for topical use in the United States and many other countries. Prescription required for ophthalmic preparations. FDA-approved for topical wound care. Included on the WHO Model List of Essential Medicines.

How is Bacitracin administered?

Applied topically to clean wounds 1-3 times daily as an ointment (typically 500 units/gram). Available as a single-agent ointment or in combination with neomycin and/or polymyxin B. Ophthalmic ointment applied to the lower conjunctival sac 1-3 times daily. Surgical irrigation uses solutions of 50-100 units/mL. Treatment duration for minor wounds is typically 7 days or until healed.

Related Peptides

#116

Nisin

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#117

Polymyxin B

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#119

Gramicidin

Antimicrobial

#120

Daptomycin

Antimicrobial

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The information on this page is for educational and informational purposes only. It is not intended as medical advice. Always consult a qualified healthcare professional before considering any peptide or supplement. 50 Best Limited does not endorse, recommend, or promote the use of any peptide for self-administration. Read our full disclaimer.

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