When did antibiotics first appear?

The age of antibiotics is usually dated to 1928, when Alexander Fleming discovered that a mould produced a substance, penicillin, that killed bacteria. An even earlier antibacterial drug, Salvarsan, had been introduced in 1910 to treat syphilis, but it was penicillin that opened the modern era. Penicillin could not be produced in useful quantities until a team at Oxford developed methods to purify and mass-produce it in the early 1940s, just in time to treat wounded soldiers in the Second World War. The first widely used antibiotic effective against a broad range of bacteria, streptomycin, followed in 1943.