| an antibiotic polypeptide derived by the hydrolytic action of Bacillus subtilis on protein, primarily used topically in the treatment of superficial infections caused by susceptible Gram-positive organisms. |

bacitracin bac·i·tra·cin (bās'ĭ-trā'sĭn)
n.
A polypeptide antibiotic obtained from a strain of the bacterium Bacillus subtilis and used as a topical treatment for certain bacterial infections, especially those caused by cocci.