Bacitracin is polypeptide product of bacillus subtilis that inhibits the formations of bacteria cell-wall peptidoglycan by complexing directly with the pyrophosphate carrier & inhibiting the dephosphoylation reaction required for its regeneration.

It is bactericidal to gram +ve bacteria but has little activity against gram – veorganisms.

The main antibacterial activity of his antibiotic is due to the bacitracin Acomponent.

The speed of bactericidal action being directly proportional to its concentration & therefore, to its dose