Abstract The invasiveness of 2 grud sensitive and 8 holy-resistant M. tuberculosis clinical isolated was
evaluated in experiments on BALB/c mice. Mycobacterial suspension was injected into the caudal vein of
experimental animals. The results were evaluated by the degree of contamination of lungs and spleen of
infected animals euthanized at different periods on time. The study revealed high variability in the
degree of contamination of the organs of the animals infected with M. tuberculosis drug-resistant clinical isolates.
