This is one of several articles sponsored by the American Society for Clinical Pharmacology and Therapeutics. The goals are as follows: (1) maximally effective drug therapy, (2) reduction of the incidence of serious adverse drug reactions, and (3) maximum effectiveness and safety at the lowest cost for the patient.
To accomplish the goals set forth with antimicrobial agents, it is necesssary that the physician have a basic understanding of the constantly changing relationships between microbes, the human host, and antimicrobial agents.1
Both microbes and humans are in a constant state of change. The growth rates of microbes and their degrees of susceptibility to antimicrobial agents may change via a number of different mechanisms. For instance, during a single course of therapy a microbe may become resistant to the antimicrobial agent by (1) emergence of genotypic drug resistance or (2) transfer of resistant factor (R) or (3) alterations in microbe