Figure 2.

Lung infection initiated via the intravenous (i.v.) route progressed more slowly than when initiated via the airborne route. Mice were infected with approximately 10² colony-forming units (CFU) of wild-type (WT) H37Rv via the airborne route, 10⁵ CFU of SR H37Rv via the i.v. route, or 10² WT H37Rv via the airborne plus 10⁵ SR H37RV via the i.v. route. (a) CFU as determined by plating lung homogenates on standard nutrient agar show that lung infection progressed more slowly in mice infected via the i.v. route. (b) CFU as determined by plating lung homogenates of streptomycin-containing agar show that infection caused by SR H37Rv that reached the lungs after i.v. infection progressed more slowly and was controlled earlier at a lower level in the presence or absence of WT H37Rv delivered via the airborne route. Means ± SD of four mice per group.