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any of a variety of substances, usually obtained from microorganisms, that inhibit the growth of or destroy certain other microorganisms. Types of Antibiotics
..... Click the link for more information. obtained from the bacterial species Bacillus brevis, which is found in soil. Gramicidin is particularly effective against gram-positive bacteria (see Gram's stainGram's stain,
laboratory staining technique that distinguishes between two groups of bacteria by the identification of differences in the structure of their cell walls. The Gram stain, named after its developer, Danish bacteriologist Christian Gram, has become an important tool
..... Click the link for more information. ). Because the drug is highly toxic, it cannot be administered internally and so is used only on the skin as a lotion or ointment. It is used primarily in the treatment of infected surface wounds, and in eye, nose, and throat infections. In 1939 the American microbiologist René Dubos isolated the substance tyrothricin and later showed that it was composed of two substances, gramicidin and tyrocidine. These were the first antibiotics to be manufactured commercially.
a medicinal preparation of the antibiotic group, bacteriostatic and bactericidal against streptococci and staphylococci, the causative microorganisms of anaerobic infections, and other microbes. Gramicidin is applied locally as a solution or paste in the treatment of suppurative and inflammatory diseases, ulcers, and bedsores, as well as in the form of a paste as a contraceptive.