The prevention of antibiotic resistance during treatment

Prevention of emergence of antibiotic resistance during treatment is an imp ortant goal when prescribing antimicrobials. Antibiotic resistant bacteria can emerge in three main ways - by acquisition of new genes via transposons or horizontal gene transfer, by selection of resistant variants and by sel ection of naturally resistant strains. In order to minimize emergence of an tibiotic resistance during therapy it is important to try and avoid antibio tics which encourage the transfer of resistance genes, to avoid selection o f resistant variants from susceptible pathogens and to avoid ablation of an tibiotic susceptible normal nora. However, implementing these objectives is not always easy. This paper discusses possible ways of limiting the emerge nce of resistant bacteria during treatment. It does not consider how to pre vent the spread of these strains from person to person. The prevalence of a ntibiotic-resistant bacteria depends upon the selection of antibiotic-resis tant strains and spread of these strains from person to person. Prevention therefore consists of two parts the prevention of acquisition of resistance /selection of antibiotic-resistant variants and interrupting the mechanisms by which person-to-person spread can occur. This paper considers only the first of these two influences on prevalence of resistance.