CHAPTER XXIII. 
LEPROSY AND ACID-FAST BACTERIA OTHER THAN 
THE TUBERCLE GROUP. 
Bacillus Lepr.«. The Smegma Bacillus. 
Leprosy of Rats. The Nasal Secretion Bacillus. 
AciD-F.\sT Bacilli Other than Bacillus Bacillus Phlei. 
Tuberculosis and Bacillus Lepr.e. The Butter Bacillus. 
BACILLUS LEPR^. 
The first definite observation of the organism now called Bacillus 
leprae was that of Hansen/ who described rod-shaped organisms in 
leprous tissue. Somewhat later Xeisser^ succeeded in staining them. 
Sticker^ made the important discovery that the nasal mucosa and 
nasal secretion of a large percentage of lepers (140 out of a total of 
153 cases examined) contain large numbers of leprosy bacilli. The 
organism described by Hansen is generally accepted as the causative 
agent of leprosy. 
Morphology.— ]Morphologically B. leprae resembles B. tuberculosis. 
It is a slender, rod-shaped organism, measuring from 4 to 6 microns 
in length. Usually it is somewhat shorter than the tubercle bacillus, 
curved forms are less common, and the ends of the bacilli are not 
infrequently somewhat enlarged. They occur characteristically as 
clusters of bacilli, grouped together in large numbers in bimdles like 
cigars, lying within large cells— the so-called lepra cells. They never 
form chains. The organisms from young lepra nodules are even 
more acid-fast than the tubercle bacillus; in old, degenerating nodules 
they tend to lose their acid-fastness and other staining properties, 
and the cytoplasm becomes vacuolated, giving the bacilli a beaded 
appearance. B. leprae is Gram -positive as well as acid-fast. Available 
evidence indicates that the organism is non-motile, possesses no 
flagella, and forms no capsules. 
Bacillus leprae differs somewhat from B. tuberculosis in its staining 
reactions and occurrence in lesions. 
Bacillus Lepr.«. Bacillus Tuberculosis. 
1. Stains with aqueous solutions of basic Does not stain with these dyes. 
anilin dyes. 
2. Stains readily by Gram's method. Stains with difficulty. 
3. Resists decolorization by the Ziehl- Somewhat more readily decolorized. 
Neelsen stain. 
4. Large numbers of acid-fast bacilli Relatively fewer acid-fast bacilli found 
occur within swollen cells — lepra together as a rule; no cells resembling 
cells. lepra cells. 
1 Virchow's .4rch., 1880, 79, 32. 
2 Ibid., 1881, 84, 514. 
3 Miinchen. klin. Wchnschr., 1897, 44, 1063, 1103. 
