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 synergy level, the boosted antimicrobial potency provided by synergy allows the body to more rapidly clear infections, resulting in shorter courses of antibiotic therapy. Shorter courses of therapy in turn reduce the effects of dose-related toxicity, if applicable. Additionally, synergy aids in total bacterial eradication, more completely removing an infection than would be possible without synergy. At a higher level, synergistic effects are useful for combating resistant bacterial strains through increased potency and for stalling the spread of bacterial resistance through the total eradication of infections, preventing the evolutionary selection of resistant cells and strains. Current research on antibiotic synergy and