FIG. 3.
Recovery of B. pertussis CFU from infected mice. (A) Mean CFU/mouse (n = 5) in output recovered from lung and tracheal homogenates, represented as the fraction of the input CFU (∼2 × 106 total CFU of a 1:1 mixture of wild-type strain UT25Sm1 [filled symbols] and heme utilization mutant strain PM5 [open symbols]), as a function of time postinfection (days). Circles, infections without hemin coadministration; squares, infections with coadministration of 2 μM bovine hemin chloride. Standard deviations did not exceed 15% of any mean CFU value determined. (B) Competitive index values calculated from mean CFU/ml of coinfecting strains at various times postinfection. Squares, infections without hemin coadministration; circles, infections with coadministration of 2 μM bovine hemin chloride. The dashed line at a y value of 1.00 corresponds to the hypothesized CI if there were no difference in fitness between the strains in vivo.