1 86 BACTERIA 



Cultures. On gelatine it produces small punctiform colonies 

 that are white, and become, after a time, surrounded by a distinct 

 halo. The colonies are often very delicate and ragged. The gel- 

 atine is not liquefied. On agar the growth is best if glycerine is 

 present, but is not characteristic. Bouillon cultures cause an 

 abundant sediment, above which the medium is clear. Milk is co- 

 agulated. On potato the growth is characteristic. The color is, 

 at first, yellowish-white like honey, becoming, finally, reddish- 

 brown. The potato is much darkened. 



Pathogenesis. This organism is pathogenic for horses and man; 

 50 percent of men succumb after infection. Horses, asses, cats, 

 dogs, sheep, and goats are susceptible in the order mentioned. 

 Cattle and birds are immune. In horses the disease is known as 

 glanders, or farcy, and the avenue of infection determines the clin- 

 ical form of the disease. The mucous membrane and the skin are 

 the chief places of infection. A primary ulcer is formed in the 

 mucous membrane of the nose, or in the skin. Subsequently, the 

 lymph glands and the lungs may be infected. Guinea pigs are 

 easily infected. White and gray mice, and rats are immune. For 

 purposes of diagnosis guinea pigs are inoculated, but care must be 

 used, as several fatal cases have occurred in laboratory workers, 

 it being a treacherous organism with which to work. In infected 

 animals, it produces a rapid and marked inflammatory reaction, 

 with the formation of pus. Certain "buds," or nodules are formed, 

 which are between an abscess and a tubercle in structure. 



The diagnosis of doubtful cases may be made by injecting the 

 material into the peritoneum of male guinea pigs. A violent 

 suppurative orchitis occurs from which the rods can be cultivated. 

 The poisons are endotoxic. 



Agglutinations. It has been shown by McFadyean that the 

 blood of infected horses exhibits markedly agglutinative properties 

 toward the glanders bacilli. A slight immunity is present after 

 an attack. 



Mallein. In old cultures a peculiar tuberculin-like substance 



