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 potential therapies is moving in three primary directions. Some research is devoted to finding combinations of extant antibiotics which when combined exhibit synergy. A classic example of this effect is the interaction between β-lactams, which damage the bacteria cell membrane, and aminoglycosides, which inhibit protein synthesis. The damage dealt to the cell wall by β-lactams allows more aminoglycoside molecules to be taken up into the cell than would otherwise be possible, enhancing cell damage. In some cases, antibacterial combinations restore potency to ineffective drugs. Other research has been devoted to finding antibiotic resistance breakers (ARB's) which enhance an antibiotic's potency.