Bacitracin:
- It is complex polypeptide isolated from Bacillus subtilis
- Commercial bacitracin is actually a mixture of 5-10 separate components, out of which bacitracin A is most active and major components.
Mechanism of action:
- Bactoprenol is lipid membrane carrier in bacteria that transports building blocks across the cytoplasmic membrane. Phosphorylated bactoprenol is necessary to transport peptidoglycan components outside cell membrane.
Bacitracin interferes with dephosphorylation in cycling of bactoprenol
Bactoprenol cannot transport peptidoglycan subunits to growing cell wall
Inhibition of peptidoglycan synthesis
Inhibition of cell wall synthesis
Antimicrobial spectrum:
- It is narrow spectrum antibiotic
- It is effective against penicillinase producing Staphylococcus aureus.
- In general, it is effective against gram +ve and spirochetes
- Rate of bactericidal action is dose-dependent, and activity is not affected by blood or tissue debris.
Bacterial resistance:
- Bacterial resistance to bacitracin is rare.
Pharmacokinetics:
- It is not absorbed from G.I tract when administered orally
- It is not used parenterally because of high-systemic toxicity.
- Topical application doesnot cause significant systemic absorption.
Side effects/Adverse effects:
- Nephrotoxicity is manifested by albuminuria, cylinduria & azotemia.
- Parenteral administration also produce pain, indurations and petechiae at site of injection.
- Occasional hypersensitivity.
Clinical use:
- It is mostly used topically for skin, ear and eye infection
- Often used in combinations with neomycin/polymyxin B to enhance antibacterial effects in ointments, dusting powders & solutions applicable to infected wounds/ulcers.
- Zinc/magnesium bacitracin is used in swine and poultry ration to prevent and treat clostridial enteritis and promote growth.