/bas'i tray"sin/ , n. Pharm.
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.
[ 1940-45; BACI(LLUS) + (Margaret) Trac ( y ) (b. 1936), American child whose tissues were found to contain Bacillus subtilis + -IN 2 ]