Tsansmission of Mycobacterium leprae into Mouse Foot-pads

Part 1. Results with a wild strain of M. leprae obtained in Japan

Abstract

The authors observed a limited multiplication of acid-fast bacilli in mouse foot-pads inoculated with Mycobacterium leprae from an untreated patient with lepromatous leprosy in this country. There was no evidence of bacillary increase in any of the mice inoculated with a heat-killed suspension. Nor were any macroscopically visible changes noted. The acid-fast bacilli in the inoculum and the harvest were transferred to Ogawa's egg media, and incubated at 33°C and 37°C. The cultures were negative, eliminating the possibility of superinfection by culturable mycobacteria. Subcutaneous inoculations of mice in the abdomen did not produce any lesions, indicating that Mycobacterium lepraemurium, a known unculturable mycobacterium, did not exist in the inoculum and the harvest. There was an arrest in the multiplication of the bacilli at about 10⁵ to 10⁶ per foot-pad. These findings were compatible with those of Shepard and others, who recently reported degrees of successful transmission of leprosy to mice. It is likely that the authors isolated a strain of M. leprae in mouse foot-pads. The viability of M. leprae was not affected by freezing and storing at -30°C for 18 days.