Phenotypic consequences of the most common rpoB mutants. Phenotypic consequences of the most common rpoB mutants. (a) In vitro fitness of the most frequent Rifr mutations. The growth rate for each bacterial strain was measured at least in triplicate from independent cultures. Each biological replicate is represented by individual data points, and the variability for the doubling time measure for the different strains is depicted with Tukey whisker boxplots. The bottom and top hinges correspond to the first and third quartiles (the 25th and 75th percentiles). RpoB mutants with a median doubling time that differed significantly (P < 0.05 by two-tailed Wilcoxon rank sum test) from doubling time for the wild-type strain are indicated with an asterisk. (b) Vancomycin MIC measured by macro Etest and HI broth microdilution. (c) Daptomycin MIC measured by macro Etest. (d) Vancomycin population analysis profile (PAP). Bars represent the measured area under the curve (AUC) ratio of each mutant versus the reference hVISA strain Mu3 (ATCC 700698). Etest and broth microdilution MIC values were measured by two independent experiments (biological replicates) and the plates were read in a blind manner (researchers reading the plates did not know which strains were being read). The histograms represent average MIC values. For PAP, single cultures were diluted and plated two times at 10−3 and 10−6 (technical replicates). The average CFU on BHI plate with vancomycin at 0, 0.5, 1, 1.5, 2, 2.5, 3, and 4 μg per ml were used to calculate AUC. All measured values are reported in Table S4 in the supplemental material. Romain Guérillot et al. mSphere 2018; doi:10.1128/mSphere.00550-17