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
Quinolone antibiotic 4-quinolones, are gemifloxacin (Factive) and trovafloxacin (Trovan) (removed from clinical use). In development. Quinolones have been widely used in animal husbandry, and several agents have veterinary-specific applications. Quinolone antibiotic A quinolone antibiotic is any member of a large group of broad-spectrum bactericides that share a bicyclic core structure related to the compound 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as well as in animal husbandry. Nearly all quinolone antibiotics in use are fluoroquinolones, which contain a fluorine atom in their chemical structure and are effective against both Gram-negative and Gram-positive bacteria. One example is