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INTRODUCTION TO ANTIMICROBIAL DRUGS
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The emergence of microbial resistance poses a constant challenge to the use of antimicrobial drugs. Mechanisms underlying microbial resistance include the production of antibiotic-inactivating enzymes, changes in the structure of target receptors, increased efflux via drug transporters, and decreases in the permeability of microbes’ cellular membranes to antibiotics. Strategies designed to combat microbial resistance include the use of adjunctive agents that can protect against antibiotic inactivation, the use of antibiotic combinations, the introduction of new (and often expensive) chemical derivatives of established antibiotics, and efforts to avoid misuse of antibiotics.