Gramicidin is a polypeptide antibiotic mixture of gramicidin A , gramicidin B, and gramicidin C originally isolated from B. brevis.1 It is also a component of the antibiotic tyrothricin .2 Gramicidin is active against the Gram-positive bacterium S. aureus but not Gram-negative E. coli.3 It also protects mice from Pneumococcus infection in vivo when administered at a dose of 0.002 mg/animal. Gramicidin inhibits growth of bacteria by forming pores and channels in the cell wall, which increases its permeability to monovalent cations.1 Formulations containing gramicidin have been used as topical agents in the treatment of bacterial skin infections.
1.Wallace, B.A.Gramicidin channels and poresAnnu. Rev. Biophys. Biophys. Chem.19127-157(1990) 2.Brewer, G.A.GramicidinAnalytical profiles of drug substances8179-218(1979) 3.Dubos, R.J., and Hotchkiss, R.D.The production of bactericidal substances by aerobic sporulating bacilliJ. Exp. Med.73(5)629-640(1941)