<P> Florey credited Rene Dubos with pioneering the approach of deliberately and systematically searching for antibacterial compounds, which had led to the discovery of gramicidin and had revived Florey's research in penicillin . In 1939, coinciding with the start of World War II, Dubos had reported the discovery of the first naturally derived antibiotic, tyrothricin, a compound of 20% gramicidin and 80% tyrocidine, from B. brevis . It was one of the first commercially manufactured antibiotics and was very effective in treating wounds and ulcers during World War II . Gramicidin, however, could not be used systemically because of toxicity . Tyrocidine also proved too toxic for systemic usage . Research results obtained during that period were not shared between the Axis and the Allied powers during World War II and limited access during the Cold War . </P> <P> Synthetic antibiotic chemotherapy as a science and development of antibacterials began in Germany with Paul Ehrlich in the late 1880s . Ehrlich noted certain dyes would color human, animal, or bacterial cells, whereas others did not . He then proposed the idea that it might be possible to create chemicals that would act as a selective drug that would bind to and kill bacteria without harming the human host . After screening hundreds of dyes against various organisms, in 1907, he discovered a medicinally useful drug, the first synthetic antibacterial salvarsan now called arsphenamine . </P> <P> The era of antibacterial treatment began with the discoveries of arsenic - derived synthetic antibiotics by Alfred Bertheim and Ehrlich in 1907 . Ehrlich and Bertheim experimented with various chemicals derived from dyes to treat trypanosomiasis in mice and spirochaeta infection in rabbits . While their early compounds were too toxic, Ehrlich and Sahachiro Hata, a Japanese bacteriologist working with Erlich in the quest for a drug to treat syphilis, achieved success with the 606th compound in their series of experiments . In 1910 Ehrlich and Hata announced their discovery, which they called drug "606", at the Congress for Internal Medicine at Wiesbaden . The Hoechst company began to market the compound toward the end of 1910 under the name Salvarsan . This drug is now known as arsphenamine . The drug was used to treat syphilis in the first half of the 20th century . In 1908, Ehrlich received the Nobel Prize in Physiology or Medicine for his contributions to immunology . Hata was nominated for the Nobel Prize in Chemistry in 1911 and for the Nobel Prize in Physiology or Medicine in 1912 and 1913 . </P> <P> The first sulfonamide and the first systemically active antibacterial drug, Prontosil, was developed by a research team led by Gerhard Domagk in 1932 or 1933 at the Bayer Laboratories of the IG Farben conglomerate in Germany, for which Domagk received the 1939 Nobel Prize in Physiology or Medicine . Sulfanilamide, the active drug of Prontosil, was not patentable as it had already been in use in the dye industry for some years . Prontosil had a relatively broad effect against Gram - positive cocci, but not against enterobacteria . Research was stimulated apace by its success . The discovery and development of this sulfonamide drug opened the era of antibacterials . </P>

Research how the following classes of antibiotics affect and destroy bacteria