CONSEQUENCES OF INCREASING RESISTANCE TO ANTIMICROBIAL AGENTS

The correlation between in vitro bacterial susceptibility results and clinical outcome has been debated for many years. Bacterial resistance traits are more significantly correlated with failure of therapy than is an organism's susceptibility to an antimicrobial agent. We review the situations that have supported the clinical relevance of in vitro bacterial resistance. Those situations include: emergence, during ther apy, of a new resistance marker not known before; selection of a resis tant mutant or acquisition of a resistance gene during therapy; failur e to recognize or take into account a new resistance mechanism; and su perinfection with resistant bacteria. More information should be obtai ned in the future by performing studies oriented toward bacteriologica lly documented clinical failures and by better communication between m icrobiologists and physicians to correlate the in vitro data with host status, the pharmacokinetics of the antimicrobial agent, and the bact eriologic and clinical outcome.