INFECTION OF CLETHRIONOMYS G. GLAREOLUS SCHREB. (RED MICE) WITH MYCOBACTERIUM TUBERCULOSIS INJECTED INTRAVENOUSLY

Abstract

Groups of red mice were injected intravenously with doses varying from 11 viable units to about 108 viable units of a virulent strain of M. tuberculosis grown in Dubos Tween medium and dispersed by means of ultrasonics. The course of the infection was determined by quantitative culture from the organs of animals killed at various times after the injection and by the survival times of animals that died spontaneously. Quantitative culture showed that the tubercle bacilli multiplied strongly in the organs during the first 2–3 weeks after the injection. Multiplication then ceased completely in liver, spleen and lungs; in the lymph glands the bacilli continued to multiply but at a very slow rate. After the period of initial multiplication, the number of bacteria in liver and spleen decreased gradually during the whole experimental period (1 year), although it varied considerably from animal to animal after the second month. In the lungs, the number remained almost constant in the animals injected with large doses, but in those given doses ≥ 104 viable units, it became reduced from the second month, and in some cases the bacteria disappeared completely. Total elimination of the bacteria was also observed in the liver and spleen of a few animals but never in the lymph glands. The mean survival times of animals injected with the four largest doses were prolonged from 81 to 310 days the smaller the dose. In the animals injected with doses ≥ 104 viable units, the mean survival times, which were independent of dosage, were not significantly different and not significantly less than those of a group of non‐infected animals. The macroscopical tuberculous lesions were small in all groups. Enlargement of the spleen, slightly enlarged lymph glands and possibly tubercles in the lungs were the most frequent findings. The number of bacteria in the organs was large in all animals injected with the large doses, but only in about half of those given small doses.