THE LEPROSY BACILLUS 439 



was withdrawn showed leucocytes filled with acid-fast bacilli arranged in ray fungus form. 

 Cultivation from this lump yielded a white, slowly growing, wrinkled culture of an organism 

 that was moderately acid-fast, resisting 20 per cent. HNO3 for 3 minutes. From the same 

 leper he also obtained a pleomorphic diphtheroid bacillus that resisted 2 per cent. H2SO4 

 for 3 seconds. Injection of this organism into a mouse produced lesions in the spleen, 

 liver, and lungs ; these lesions contained clumps of acid-fast bacilli. Bayon concludes 

 that the bacillus of human leprosy has a non-acid-fast, a weakly acid-fast, and a fuUy 

 acid-fast stage. In 1912 Duval and Wellman reported on 29 cases of leprosy ; from 14 

 they isolated an acid-fast chromogenic bacillus like Clegg's ; from 8 an acid-fast non- 

 chromogenic bacillus similar to Duval's ; and from 1 a non-acid-fast diphtheroid bacillus 

 like Kedrowski's. Injection of the 2 acid-fast strains into a number of animals, including 

 monkeys, caused small lesions, which, however, could not be diiferentiated from those 

 produced by the saprophytic acid-fast bacilli. In 1912 Currie, Clegg and HoUmann stated 

 that they had isolated by Clegg's method an acid-fast bacillus 16 times from 15 cases of 

 leprosy. All strains were chromogenic, and were culturally similar to the saprophytic 

 acid-fast bacilli ; they could be distinguished from these, however, by agglutination with 

 a specific antiserum prepared by injection of the horse, though they were rarely agglutinated 

 by the sera of lepers. A similar organism was isolated by McCoy in 1914 from 11 out of 

 83 specimens of leprous tissue ; cultures were obtained with about equal facility whether 

 amoebae were present or not. The organism was incapable of producing leprosy-like 

 lesions in laboratory animals. 



More recently a number of apparently successful attempts to cultivate the leprosy 

 bacillus have been recorded. Shiga (1929) stated that by treating lepra nodules with 5 

 per cent. H2SO4 and inoculating them on to glycerol potato, he was able to obtain minute 

 colony formation in about 2 months. Subcultures were carried on for four generations. 

 Schlossmann (1930, 1933) claimed to have obtained growth in sealed tubes of Martin's 

 broth in 4 months, and Sonnenschein (1930) in sealed tubes of glycerol egg in 2 months. 

 The most hopeful results, however, have been recorded by Soule and Mclvinley (1932), and 

 Soule (1934). These workers inoculated saline suspensions of excised lepra nodules on to 

 several different media, and following Wherry's (1930) recommendation, incubated the 

 cultures in varying partial pressures of oxygen and carbon dioxide. In a number of 

 instances they succeeded in obtaining colony formation after 6 weeks at 37° C. Several 

 media yielded growth, including glycerol potato, Dorset egg, Petroff egg, and hormone 

 glycerol agar. The most favourable gaseous conditions were afforded by a mixture of 40 

 per cent, oxygen and 10 per cent. COg. Sixty serial subcultures were made over a period 

 of 6 years (McKinley and de Leon 1937). The colonies themselves were about 1 mm. 

 in diameter, heaped up, non-chromogenic, with a mucoid appearance and a loose fila- 

 mentous border. Microscopically they consisted of acid-fast bacilU. Similar success is 

 said to have attended the cultivation of the bacilli in a minced chicken embryo medium 

 incubated under suitable partial pressures of O2 and COj (McKinley and Verder 1933). 

 SaUe and Moser (1937) report success by both these methods, but Lowe and Dharmendra 

 (1937) and Dharmendra and Lowe (1938) obtained completely negative results in an exten- 

 sive trial. (For further review of bacteriology of leprosy, see McKinley 1934, Soule and 

 McKinley 1938.) 



This resume, which is by no means complete, illustrates the variety of organisms 

 that have been cultivated from leprosy. It will be seen that they fall into three 

 classes : (i) diphtheroid bacilli, which are either non-acid-fast or weakly acid-fast, 

 (ii) chromogenic acid-fast bacilli, and (iii) non-chromogenic acid-fast bacilli. What 

 relation, if any, these organisms bear to leprosy, it is at present impossible to say. 

 We are faced with three possibilities : either (i) they are contaminating organisms 

 that have nothing to do with the causation of leprosy ; or (ii) they are different 

 stages in the life-history of the true leprosy bacillus ; or (iii) they are organisms whose 

 presence is in some way associated with that of the true leprosy bacillus, which has 



