Bacillus Murisepticus, Koch (1878). 

 MOUSE SEPTICEMIA; MAUSESEPTIKAMIE (Germ.). 



ORIGIN. From mice after inoculation with putrid blood. It is 

 widely distributed in water, soil, etc. 



FORM. The rods are narrower and thinner than those of the 

 rouget bacillus, but otherwise resemble the latter very much. 



MOTILITY. Appears to possess motion, but is really non-motile. 



SPORULATION. Round, glistening- bodies form within the cells as 

 in the case of rouget. They have nothing- to do with spores. 



ANILIN DYES. Stain rapidly. Gram's method is applicable. 



GROWTH. Is rather slow and resembles very closely that of the 

 roug-et bacillus. 



Plates. The colonies on the gelatin plate resemble those of the rouget bacillus, ex- 

 cept that they spread [somewhat more rapidly and are more delicate and transparent in 

 appearance. 



Stab culture. Shows this distinction in growth quite sharply. While the cloudy 

 growth of the rouget bacillus is dense and somewhat limited to the line of inoculation, that 

 of the mouse septicemia bacillus is lighter and spreads readily throughout the entire gela- 

 tin. This difference is clearly seen in young cultures. 



Streak culture. On agar the growth is scarcely to be distinguished from that of the 

 rouget bacillus. Glycerin agar is most suitable. 



Bouillon. The bacillus develops a growth similar to that of the bacillus of rouget. 



OXYGEN REQUIREMENTS. It is a facultative aerobe and hence grows 

 best when air is excluded. 



TEMPERATURE. It grows well at the ordinary temperature. Opti- 

 mum about 35-37. 



BEHAVIOR TO GELATIN. Ordinarily no liquefaction can be observed. 

 Sometimes, however, the gelatin gradually softens. 



AEROGENESIS. Produces less hydrogen sulphide than the rouget 

 bacillus. 



ATTENUATION. Old cultures possess diminished virulence. 



IMMUNITY. Rabbits that recover after one inoculation with the 

 pure culture are rendered immune against subsequent inoculation. 

 They are at the same time immune against the rouget bacillus. 



PATHOGENESIS. White mice, house mice, pigeons, sparrows and 

 rabbits are susceptible. Chickens, guinea-pigs and field mice are 

 wholly immune. After death the bacilli are distributed throughout 

 the body, single or in pairs, and are frequently inclosed in leucocytes. 



DIAGNOSIS. In cultural, morphological and pathogenic properties 

 it resembles very closely the preceding organism. So much so that 

 it is commonly considered to be an attenuated form of the rouget 



bacillus. 



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