bacitracin a

from The Collaborative International Dictionary of English v.0.48
bacitracin \bacitracin\ n. (1940) [Bacillus + Margaret Tracy, (a
   child whose tissues contained {Bacillus subtilis}) + -in.
   --RHUD.]
   a polypeptide antibacterial antibiotic of known chemical
   structure effective against several types of Gram-positive
   organisms, and usually used topically for superficial local
   infection.

   Note: It is produced by {Bacillus subtilis} and {Bacillus
         licheniformis}, and as produced commercially is
         composed of several closely related substances. The
         predominant component, {Bacitracin A}, has a formula
         {C60H103N17O16S}, and contains D-ornithine,
         D-phenylalanine and D-glutamine residues as well as the
         L-isomers of leucine, isoleucine, histidine, asparagine
         and aspartic acid. --[MI11]
         [WordNet 1.5]