Statistical significance analysis (GraphPad Prism 6.0h) was performed using one-way or two-way analysis of variance (ANOVA) with the Bonferroni posttest unless otherwise indicated in the figure legends. Bacteriolysis assay data were log transformed prior to statistical analysis (*, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001).