Antibiotic antibiotic therapy. The antibiotic treatment may select for bacterial strains with physiologically or genetically enhanced capacity to survive high doses of antibiotics. Under certain conditions, it may result in preferential growth of resistant bacteria, while growth of susceptible bacteria is inhibited by the drug. For example, antibacterial selection for strains having previously acquired antibacterial-resistance genes was demonstrated in 1943 by the Luria–Delbrück experiment. Antibiotics such as penicillin and erythromycin, which used to have a high efficacy against many bacterial species and strains, have become less effective, due to the increased resistance of many bacterial strains. Resistance may take the form
Antibiotic gastric juices and hydrogen peroxide). It also excluded synthetic antibacterial compounds such as the sulfonamides. In current usage, the term "antibiotic" is applied to any medication that kills bacteria or inhibits their growth, regardless of whether that medication is produced by a microorganism or not. The term "antibiotic" derives from "anti" + βιωτικός ("biōtikos"), "fit for life, lively", which comes from βίωσις ("biōsis"), "way of life", and that from βίος ("bios"), "life". The term "antibacterial" derives from Greek ἀντί ("anti"), "against" + βακτήριον ("baktērion"), diminutive of βακτηρία ("baktēria"), "staff, cane", because the first bacteria to be discovered were rod-shaped. The