The role of the microbiology laboratory in guiding formulary decisions.

Typically, P & T Committee antibiotic selection criteria have included such factors as cost, pharmacokinetics, side effects profile, spectrum of activity, and relative activity against specific pathogens. The microbiology laboratory can provide the P & T Committee with other useful information to help guide them in making even more appropriate and cost-effective formulary decisions. This information includes specific susceptibility data (including prevalence of pathogens, source of infection [community or nosocomial], anatomical site of isolates, specific unit or service where isolated, type of culture specimen, total number of pathogens in the hospital), resistance trends data, an evaluation of microbiologic data presented in published studies, further data regarding an antimicrobial's spectrum of activity and activity against specific pathogens, and the relevance and limitations of in vitro data. With this information in hand, P & T Committee should be in a much better position to optimize formulary decision-making.