[Statistical methods for description of phenotypic susceptibility data].

This paper summarizes statistical methods to describe susceptibility data. A frequent data basis in resistance studies are minimum inhibitory concentrations (MICs), measured for different antimicrobial agents. In the statistical context these (semi) quantitative MIC values are ordinal scaled. Therefore, they should be analysed with statistical tools appropriate for ordinal data. The resistance situation for each antimicrobial agent is often described using frequency distributions of MIC values. Resistance patterns can be described by frequencies of resistance profiles. More detailed insights into appearance and changes of simultaneous resistance against different agents are provided by a systematic analysis of dependency structure in susceptibility data. Furthermore, the calculation of differences between resistance profiles using appropriate distance measures enables the application of common methods of multivariate statistic for description and more complex analysis of susceptibility data. To improve the comparability of study results, it is desirable to present as much information as possible in a uniform way.