Effect of “R'and “S'Forms of Chromogenic Acid-Fast Bacillus from Human Leprous Lesion on Rabbits

Abstract

The writer isolated 1 a “rough'and “smooth'form of a chromogenic acid-fast bacillus which was recovered from the human leprous lesion. The 2 forms differed both morphologically and culturally. A study was made to determine any difference in pathogenicity. Inoculations of rabbits began about a year ago. Large doses of the 2 forms were given at frequent intervals over a considerable length of time. Three rabbits were respectively injected with the “R'form subcutaneously, intraäbdominally and intranasally, and 3 other animals received the “S'form by the same routes. Preliminary to the injections of living bacilli, all 6 rabbits received several injections of a lepra broth-filtrate to produce, if possible, an allergic condition which would enhance the growth of the acid-fast bacilli in vivo. 2

The “S'form produced the most striking results. The rabbits became markedly emaciated after approximately 7 months. Several subcutaneous nodules were noted at the sites of inoculations in the rabbits receiving the subcutaneous injections. Microscopic examination of ulcerated nodules revealed many acid-fast bacilli. The internal organs, especially the liver, spleen and kidneys, showed many large phagocytic cells, simulating lepra cells, containing acid-fast bacilli. Fibrosis and generalized thickening of the blood vessels was marked. Two rabbits showed paralysis of 2 or more extremities which probably was the result of extra- and intraneural fibrosis. Less conspicuous changes were noted in the rabbits injected with the “R'form. Emaciation was present but not to the degree seen in the rabbits that had received the “S'injections. Subcutaneous nodules developed but gradually disappeared without ulceration. Careful microscopic examination of the internal organs of the “R'animals revealed nothing characteristic of leprosy. No acid-fast bacilli were detected in any of the organs.

One of the objects of this investigation was to determine whether it is possible to induce in rabbits. by means of the chromogenic acidfast bacillus isolated from the human leprous nodule, a disease comparable to human leprosy.