Bacitracin

Overview
Bacitracin is a mixture of related cyclic polypeptides produced by organisms of the licheniformis group of Bacillus subtilis var Tracy. Its unique name derives from the fact that the bacillus producing it was first isolated in 1943 from a knee scrape from a girl named Margaret Tracy. As a toxic and difficult-to-use antibiotic, bacitracin doesn't work well orally. However, it is very effective topically.

Bacitracin is synthesised via the so-called nonribosomal peptide synthetases (NRPSs), which means that ribosomes are not involved in its synthesis.

Mechanism of action
Bacitracin interferes with the dephosphorylation of the C55-isoprenyl pyrophosphate, a molecule which carries the building blocks of the peptidoglycan bacterial cell wall outside of the inner membrane.

Clinical use
Bacitracin is used in human medicine and is "approved by the FDA for use in chickens and turkeys."

As bacitracin zinc salt, and in combination with other topical antibiotics (usually polymyxin B and neomycin), it is 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. In the United States a popular brand name Neosporin contains Bacitracin as one of its antibiotic agents along with Neomycin and Polymyxin B. Bacitracin can also be bought in pure form for those with allergies.

It is also commonly used as an aftercare antibiotic on tattoos. It is preferred over Neosporin because of its fewer ingredients, which lowers chances of an allergic reaction.

In infants, it is sometimes administered intramuscularly for the treatment of pneumonias. This formulation is sold under the brand name Baciim®.