1939

Rene Dubos discovers soil-based tyrothricin and then he & Rollin Hotchkiss isolate gramicidin as one of two active agents. It was a powerful gram-positive antibacterial (strep, staph, pneumococcus) in test tube and peritoneal cavity of infected mouse but like tyrothricin proved extremely poisonous unlike penicillin, with its similar antibacterial spectrum F. Ryan, 151-161).