Antibiotics: Microbial Resistance

Antibiotics are compounds that either inhibit or cease the growth of microbes by targeting cellular functions that are required for maintenance or replication. Resistance to antibiotics can arise by point mutations that alter the target such that the antibiotic no longer exerts an inhibitory effect. Microbes can also acquire a gene or genes that confer resistance to the antibiotic’s inhibitory effect. This acquisition is commonly mediated by horizontal transfer of the resistance gene(s) by a plethora of mechanisms. Microbial resistance to antibiotics can emerge as a result of exposure to antibiotics in the environment or when they are used therapeutically to prevent or cure diseases. This exposure exerts a selective pressure on the susceptible microbes and can result in the selective advantage of the resistant microbe, an up-regulation of the resistance protein, or an enhanced horizontal transfer of the resistance gene(s).