The Effect of Restricted Diet and Suprarenalectomy on Experimental Tuberculosis in the White Rat.

Abstract

It has been previously demonstrated 1 that the albino rat enjoys complete immunity to infection by human tubercle bacilli in spite of the fact that the bacteria remain alive for indefinite periods and apparently multiply in the host.

In the first of these new experiments 36 rats were used and were divided into 3 groups. Twelve of these were inoculated with human, 12 with bovine and 12 with avian strains respectively of the tubercle bacillus. Six of each of these groups were on a bread and water diet and 6 on a full maintenance diet. Throughout all the experiments the dose used was 1 mgm. diluted with 1 cc. of saline and injected intraperitoneally. The strains were all pathogenic, H. 37, B. 1, and Avian, “pathogenic,” and were obtained from Trudeau Sanitarium.

Of these animals those given the human and bovine strains, when autopsied after a suitable interval, showed no macroscopic or microscopic evidence of tissue reaction. On direct smears and tissue stains many of these animals showed the presence of the tubercle bacillus. Most of the animals, however, (82%) which had been inoculated with the avian strain, showed at autopsy extensive macroscopic tuberculosis. The spleen and liver seemed especially involved. These latter results agree with those of Cobbett. 2

Each group inoculated was carefully controlled by rats fed on a normal diet. The control animals inoculated with the human strain, at autopsy were, as expected, negative. The bovine group was likewise found negative at autopsy. Of the control group inoculated with the avian strain, 50% were found at autopsy to have extensive tuberculous lesions.

We may then conclude from these experiments that the white rat is immune to the human and bovine strains of the tubercle bacillus even when its resistance is lowered by a deficient diet (white bread and water), but is susceptible to the avian strain.