indication

For the treatment of infants with pneumonia and empyema caused by staphylococci shown to be susceptible to the drug. Also used in ointment form for topical treatment of a variety of localized skin and eye infections, as well as for the prevention of wound infections. Used against gram positive bacteria. Bacitracin is also used as an inhibitor of proteases and other enzymes. However, specific activity of bactracin's inhibition of protein disulfide isomerase has been called into question.

pharmacology

Bacitracin is a mixture of related cyclic polypeptides produced by organisms of the licheniformis group of Bacillus subtilis var Tracy. As a polypeptide, toxic, and difficult to use chemical, bacitracin doesn't work well orally, however is very effective topically. Bacitracin exerts pronounced antibacterial action in vitro against a variety of gram-positive and a few gram-negative organisms. However, among systemic diseases, only staphylococcal infections qualify for consideration of bacitracin therapy.

mechanism of action

Bacitracin intereferes with the dephosphorylation of the 55-carbon, biphosphate lipid transport molecule C55-isoprenyl pyrophosphate (undecaprenyl pyrophosphate), which carries the building blocks of the peptidoglycan bacterial cell wall outside the inner membrane for construction. Bacitracin binds divalent transition metal ions (Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) which binds and oxidatively cleave DNA.

toxicity

Oral, mouse: LD₅₀ = >3750 mg/kg.

absorption

Absorption of bacitracin following intramuscular injection is rapid and complete. Absorption from the gastrointestinal tract following oral administration is not appreciable. Absorption following topical application is negligible.

route of elimination

The drug is excreted slowly by glomerular filtration.