Screening for L. monocytogenes transposon mutants with intracellular survival defects in macrophages. (A) L. monocytogenes mutants carrying bacteriolysis reporter pBHE573 that can neither access the host cytosol nor avoid bacteriolysis in the host cytosol induce low levels of luciferase production in the host. However, L. monocytogenes mutants with survival defects transfer pBHE573 to the host cytosol and induce high levels of luciferase production. (B) Approximately 6,500 random transposon mutants were tested for increased bacteriolysis within macrophages. Data are normalized to wild-type levels of bacteriolysis. Download FIG S1, EPS file, 0.5 MB.