Antibiotics or antibacterials are a type of antimicrobial used in the treatment and prevention of bacterial infection. They may either kill or inhibit the growth of bacteria. Several antibiotics are also effective against fungi and protozoans, and some are toxic to humans and animals, even when given in therapeutic dosage. Antibiotics are not effective against viruses such as the common cold or influenza, and may be harmful when taken inappropriately.
(discovery) The era of antibacterial chemotherapy began with the discovery of arsphenamine, first synthesized by Alfred Bertheim and Paul Ehrlich in 1907, used to treat syphilis. The first systemically active antibiotic, prontosil was discovered in 1933 by Gerhard Domagk, for which he was awarded the 1939 Nobel Prize.