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
A22 (antibiotic) A22 (antibiotic) A22, also known as "S"-(3,4-dichlorbenzyl)isothiourea, is a chemical compound with antibiotic activity. It is colorless, hygroscopic, and light-sensitive. A22 acts as a reversible inhibitor of the bacterial cell wall protein MreB, causing bacterial rod-shaped cells to form coccoid cells. The antibiotic activity of A22 has been studied primarily in "Pseudomonas aeruginosa." However, A22 does not seem to be useful as an antibiotic in humans due to its cytotoxic and genotoxic effects on human peripheral blood mononuclear cells (PBMCs). Despite its cytotoxic effects in human cells, A22 has been used as a research tool to investigate the bacterial cytoskeleton.