The multiplication of several mycobacteria was investigated on mice, who were inoculated subcutaneously into foot-pads; for the differentiation of M. leprae to the other mycobacteria which were found in the tissue of mice foot-pads. The results obtained were as follows;
1) The count of viable bacilli in the tissue of mouse foot-pad decreased with the period after the inoculation into foot-pad in the majority of mycobacteria except M. leprae, M. leprae-murium and M. balnei.
2) Mycobacteria were divided into four groups by the decrease of survival bacilli in thetissue of mouse foot-pad; 1st group is M. phlei and M. smegmatis, 2nd group is M. avium, Scotochromogenic and Non-photochromogenic M., 3rd group is M. bovis, M. kansasii and M. ulcerans, and 4th group is M. balnei, M. paratuberculosis and M. leparemurium.
3) The remarkable inflammatory lesion were found in paw of mice inoculated subcutaneously into foot-pads with M. lepraemurium suspended in saline solution and M. fortuitum mixtured with adjuvant. These two mycobacteria, therefore, were differentiated from the other mycobacteria on these findings of paw.
4) The heat-killed mycobacteria were found in the tissue of mice foot-pads for a long time, when these bacilli were inoculated subcutaneously into foot-pads. These killed bacilli, however, did not show the elongation and the formation of gathering, and they could not be found microscopically in the tissue of foot-pads of mice in second generation. These facts were different from the findings in mice inoculated with the viable bacilli.
From the above results, the multiplication of M. leprae was different from the growth of the other mycobacteria in the tissue of mouse foot-pad who was inoculated subcutaneously into foot-pad.
The survival time of viable mycobacteria in the foot-pads of mice inoculated with ad juvant was longer than that inoculated with saline solution. The lesion of mice in the whole body was found by the inoculation of some mycobacteria (BCG, M. kansasii) mixtured with adjuvant. This fact will show that low-virulent mycobacteria may provoke the lesion in the whole body, if these mycobacteria mixtured with adjuvant are inoculated into the foot-pads of mice.

View full abstract

The effect of BCG-vaccination upon the multiplication of M. leprae in the tissue of mice foot-pads was investigated experimentally on the preventive effect of BCG-vaccination upon the occur-rence of leprosy in human beings. As a result, the effect of BCG-vaccination was influenced with the experimental condition and not so remarkable; this vaccination was effective in one case, but it was not effective in the other case. For the clarification of this cause, the usefulness of viable bacillary count in the foot-pads of experimental animals was investigated by the infection with a culturable acid-fast bacillus, which could grow in the tissue of foot-pad.
Mycobacterium bovis (Ravenel-strain) was injected subcutaneously into the foot-pads of mice or guinea pigs vaccinated with some kinds of acid-fast bacilli and the effect of vaccination was investigated. The macroscopical findings and the viable bacillary counts of lung or spleen in vaccinated animals were less than those in unvaccinated control animals, but the viable bacillary count in the tissue of foot-pad of vaccinated animals was not different from the count in unvac-cinated animals. This result will show that the multiplication of bacilli in the infected place may be not useful for the judgement on the effect of vaccination in experimental animals.
The bacillary count in the tissue of foot-pad, however, must be used to investigate on the inhibitory effect of vaccination upon the growth of M. leprae, because the multiplication of M leprae is limited in the foot-pads of mice at present. The effect of vaccination in experimental animals is influenced by the intensity of vaccination and the virulence of acid-fast bacilli used for challenge. The virulence of M. bovis to animals is very stronger than that of M. leprae. Therefore, if the experimental animals ars vaccinated intensitively and the low-virulent bacilli are used for challenge, the bacillary count in the infected place may be used experimentally for the judgement on the effect of vaccination.

View full abstract