抗生素的循环进化军备竞赛（英文PPT）Antibiotic.ppt

An “evolutionary arms race” is an evolutionary struggle between competing sets of co-evolving genes that develop adaptations and counter-adaptations against each other, resembling an arms race. The term has been used more and more for the battle between bacteria and antibiotics. An example of a co-evolving gene set is a parasite and its host. In recent years, many bacteria and diseases have been evolving faster than humans can create new antibiotics to treat them. What are antibiotics? When someone’s immune system can’t fight off a bacterial infection by itself, they may need more aggressive medical treatment Antibiotics and other antibacterial drugs are the major weapons against disease-causing bacteria, and they can kill bacteria or suppress their activity in various ways They can be natural, synthetic, or semi-synthetic organic chemical compounds which can kill or stop the growth of infections Penicillin is the most well-known antibiotic and has been used to fight many infectious diseases, including syphilis, gonorrhea, tetanus, and scarlet fever Antimicrobial ResistanceHistory Louis Pasteur: first observed antibiotic effect in 19th century, who discovered that certain saprophytic bacteria can kill anthrax bacilli Paul Ehrlich: developed salvarsan in 1909, a synthetic compound that remained the only effective treatment for syphilis until purification of penicillin in the 1940s Sir Alexander Fleming: 1928, accidentally discovered Penicillin World War II: renewal of research, Sir Howard Florey and Ernst Chain purified enough penicillin to show that it would protect mice from infection Soon after antibiotics were introduced into clinical circulation, cases arose where their ability to effectively stop infection was decreased As the use of antibiotics became more widespread, the prevalence of antibiotic resistant bacteria increased Different time frames apply to different bacteria because the number of mutations necessary to develop resistance depend on the strain