After 6 hours or 24 hours of bacterial instillation, the numbers of CFU in lungs, BAL and spleen were determined by serial dilution on TSB agar plates. Mice (5–6 mice/group) were anesthetized with 2.5% tribromoethanol. The trachea was cannulated, the lungs were lavaged twice using 1 ml saline, and the BAL samples collected. The left lung lobe was homogenized in 1 ml saline and placed on ice. Dilution of 100 μl of lung tissue homogenate or BAL was mixed with 900 μl PBS. Four serial 10-fold dilutions in saline were prepared and plated on TSB agar plates and incubated overnight at 37 °C, each dilution plated in triplicate, for counting.