438 M YCOBA CTERI UM 



be described, very little more is known about it now than at the time of its original 

 discovery. Numerous attempts have been made to cultivate it, and many different 

 organisms have actually been isolated from the tissues of lepers, but it is by no 

 means certain that the real causative organism of the disease has yet been grown 

 in pure culture. 



In 1901 Kedrowski cultivated, apparently from 4 cases of leprosy, a non-acid-fast 

 diphtheroid bacillus showing true branching. In very young cultures, 10 to 14 hours 

 old, most of the bacilli withstood decolorization with 5 per cent. H2SO4, but in older cultures 

 the organisms were non-acid-fast except for the metachromatic granules. He stated that 

 when injected into rabbits, the organisms became acid-fast after a residence of several 

 weeks in the tissues. He thought that the bacillus belonged to the Actinomyces group, 

 and that the acid-fast rods seen in human leprosy represented only one stage in the develop- 

 mental cycle of a single pleomorphic species. In 1905 Emile-Weil obtained a growth of 

 Gram-positive, acid-fast baciUi on a medium consisting of a mixture of glycerine glucose 

 peptone agar and egg-yolk. Single colonies appeared about the 5th day, and increased 

 in size tiU the 15th or 20th day. Cultures were likewise successful in hens' eggs, the leprous 

 juice being inoculated directly into the yoUt of the whole egg. Subcultures were never 

 obtained. In 1909 Clegg cultivated from 8 out of 10 lepers a weaklj' aoid-fast chromogenic 

 bacillus. The primary cultures were obtained in symbiosis with amcsbae and cholera 

 vibrios ; by heating these cultures to 60° C. for 30 minutes, he obtained a pure culture 

 of the acid-fast bacillus. The organisms, both morphologically and culturally, resembled 

 the ordinary saprophytic acid-fast bacilli ; they resisted decolorization with alcohol for 

 3 minutes, but were largely decolorized by 5 per cent. HCl in 2 minutes. Cultures on 

 agar were of a bright orange colour. Local lesions resulted from injection of the bacilli 

 into guinea-pigs, similar apparently to those following injection of such organisms as 

 My CO. phlei and the smegma bacillus. 



In 1910 Duval cultivated from 4 cases of leprosy a non-chromogenic acid-fast baciUus ; 

 cultures were made on an agar or banana medium enriched with a 1 per cent, solution 

 of cysteine or tryptophan. GUstening white colonies 1-2 mm. in diameter appeared after 

 1 to 2 months at 32-33° C, but not at 37° C. The organisms were nearly as acid-fast 

 as the tubercle bacillus, but were decolorized by 30 per cent. HNO3 foUowed by 95 per 

 cent, alcohol ; they failed to grow on ordinary media. When injected, even in small 

 numbers, subcutaneously or intraperitoneaUy into Japanese dancing mice, they gave rise 

 to glistening white nodules, resembling miliary tubercles ; these were disseminated through- 

 out the body, but were especially numerous in the spleen and lymph nodes. These nodules 

 resembled the human lesions very closely ; they contained acid-fast bacilli in enormous 

 numbers, chiefly intracellular in position. Injection into guinea-pigs, rabbits, rats, and 

 mice was without effect. In the same year, Twort (1910) isolated an acid-fast bacillus 

 from the nasal discharge of a leper by growth on an egg medium containing a glycerine 

 extract of dead tubercle bacilli. Growth was not visible for 6 weeks. In 1911 Rost cul- 

 tivated an acid-fast, chromogenic, highly pleomorphic bacillus from 3 cases of nodular 

 leprosy at Rangoon. Primary isolation was obtained on a mUk broth medium containing 

 volatile alkaloids from rotten fish. Growth occurred in 3 days, and was yellow, pink, 

 or orange-red in colour. A monkey injected repeatedly by different routes developed small 

 nodules under the skin containing acid-fast bacilh. Using a medium similar to Rost's, but 

 in which the rotten fish distillate was replaced by distilled water, Williams in 1911 cultivated 

 two organisms from 5 cases of leprosy in Persia and Bombay ; one was a non-acid-fast 

 streptothrix, the other an acid-fast bacillus hke Rost's. In old cultures of the latter 

 organism in liquid media, a non-acid-fast diphtheroid appeared. 



In 1912 Bayon (1911-12) isolated a non-acid-fast diphtheroid bacillus, sometimes 

 showing branching, from a case of nodular leprosy in London ; it was morphologically 

 identical with Kedrowski's bacillus. Intraperitoneal injection into a rat caused a lump 

 at the site of inoculation 3 months later the lump was punctured, and the fluid that 



