USE OF MULTIVARIATE-ANALYSIS TO COMPARE ANTIMICROBIAL AGENTS ON THE BASIS OF IN-VITRO ACTIVITY DATA

Multivariate techniques such as principal component analysis or simila r factor analysis help in analyses of the simultaneous interrelationsh ips among several variables. A comparative multivariate analysis on th e in vitro activities of eight antimicrobial agents, including the nov el molecule daptomycin, is presented. Multivariate analysis detects co mponents or factors and establishes connections among antimicrobial ag ents on the basis of their different levels of participation in each f actor. The first principal component was dominated by vancomycin, teic oplanin, and rifampin (0.94344, 0.92792, and 0.72127, respectively). T he second principal component showed strong effects from imipenem, gen tamicin, and cephalothin (0.87992, 0.86126, and 0.68870, respectively) . Daptomycin stood out alone in the third principal component (0.83983 ). The first three components defined 81.5% of the total variance and could easily be represented graphically in a three-dimensional scatter plot. In this graphic representation, the eight antimicrobial agents clustered in three different spatial regions; daptomycin occupied a se parate spatial position. The use of multivariate analysis offers a dif ferent approach to determination of the in vitro activities of new ant imicrobial agents and adds some new data on the relationships among di fferent classes. Notwithstanding its limitations, the application of t hese methods in microbiology and drug development could be an addition al tool for use in processing information.