FIG. 4.

Colonization of key sites of infection. Groups of five BALB/c mice were infected i.n. with DD503 (4 × 10⁴ CFU), JW270 (3 × 10⁶ CFU), or E264 (2 × 10⁶ CFU). At 24 and 48 h postinoculation, groups of five mice were euthanized, and a third set of animals was euthanized on a case-by-case basis at the onset of terminal or late-stage disease symptoms (Term). BAL fluid (A) was collected using 1 ml of tissue lysis buffer, and blood (C) was collected by cardiac puncture. Lungs (B), spleens (D), and livers (E) were homogenized in tissue lysis buffer, and all body fluids or tissue homogenates were lysed with 1% Triton X-100 prior to serial dilution and enumeration of bacteria by plate counting. Statistically significant differences in bacterial colonization compared to DD503 colonization at the same time point are indicated by asterisks (*, P < 0.05; **, P < 0.01; ***, P < 0.001).