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 resistance in gonorrhea the "parC" gene which encodes for the topoisomerase IV. Topoisomerase IV acts similarly to DNA gyrase and is involved in unwinding DNA for replication. Ceftriaxone and cefixime are third generation cephalosporins and are often used as treatments for "N. gonorrhoeae infections". The cephalosporins are part of a larger beta-lactam family of antibiotics. The newly discovered H041 strain of "N. gonorrhoeae", originally isolated from a commercial sex worker in Japan, was shown to be resistant to this antibiotic. The possible mechanisms of resistance to this antibiotic are as follows: Tetracyclines are a class of antibiotics that inhibit protein synthesis by binding