Comparison of different <i>Y. pseudotuberculosis</i> strains for survival inside macrophages as determined by CFU assay.

BMDMs were infected with the indicated strains at an MOI of 10 for 20 min, followed by gentamicin treatment to eliminate extracellular bacteria. At 1 h and 23 h post infection, the infected BMDMs were lysed, and serial dilutions were plated to determine the survival of intracellular bacteria by CFU assay. Ratios of CFU at 23 h/1 h are shown, determined as [23 h post infection CFU/1 h post infection CFU]. Results shown are the means from three independent experiments with duplicate infection wells. Error bars show standard deviations. (A)***, P<0.001 compared to IP17; (B) *, P<0.05 and ***, P<0.001 compared to IP6, as determined by one-way ANOVA.