ECV Determination for Tildipirosin Against PM

The resistance bacteria were excluded, and the wild-type PM should be defined for microorganisms which did not have any acquired resistance mechanisms to the tildipirosin. Additionally, the ECV calculated as the peak MIC for wild-type PM comprised over 95% in the MIC distributions according to the guidelines of CLSI and the previously described reports (Turnidge and Paterson, 2007; Pfaller et al., 2010, 2011; Lei et al., 2018a). The wild-type MIC distributions were checked and amended on the basis of standard distribution at the lower end of the MIC range for attaining the suitable distribution of MICs, which was executed with Sigma-Stat software (version 3.5, Systat Software Inc., United States). The mean and standard deviation of the normal distribution for the optimum non-linear least squares regression fitting MICs were assessed based on the software of GraphPad Prism (Version 7, GraphPad Software Inc., United States). The final ECV was calculated as the MIC value that captured over 95% of the optimum MIC distributions using the NORMINV and NORDIST functions in Microsoft Excel software was based on the preceding mean and standard deviation values. In other words, the ECV could be obtained using a summarized Excel form based on the above method.