Optimal Use of Antimicrobial Agents

The word “optimal” can have a number of different meanings. It clearly would indicate the best, but to define the best use of antimicrobial drugs is far from simple. What is optimal today may be passe tomorrow. That which is optimal for the moment may be shown to be toxic at some future date. To understand the optimal use of antimicrobial agents, it is necessary to review the indications for which antimicrobial drugs are used (1). Basically there are three forms of antimicrobial drug use. The first is in defined infections in which the pathogenic microorganism has been established by culture or other means of identification such as an unequivocal Gram stain. These infections actually are infrequent. In most situations, antimicrobial use is empiric; that is, the best possible diagnosis of the etiologic pathogens has been made on the basis of clinical and laboratory information available to the physician.