Growth rate of mycobacteria in mice as an unreliable indicator of mycobacterial virulence.

The CDC1551 strain of Mycobacterium tuberculosis was compared with the H37Rv strain of M. tuberculosis and the Ravenel strain of Mycobacterium bovis for virulence in mice. Although all three strains gave rise to the same level of stationary infection in major organs, mice infected with the Ravenel strain died much earlier from lung disease.