488 



PFEIFFERELLA, AND CERTAIN ALLIED ORGANISMS 



Pf. mallei has no digestive action on serum. Both organisms may produce a 

 small amount of H2S, when tested by Huddleson's method on liver agar. (For the 

 preparation of mallein see Chapter 62.) 



Antigenically , the two organisms appear to resemble each other closely. Stanton 

 and Fletcher (1925), who examined 5 strains of Pf. mallei and 14 strains of 

 Pf. ivhitmori by agglutination, absorption, and complement fixation, found that the 

 strains of Pf. ivhitmori formed a homogeneous group, but that the 5 strains of Pf. 

 mallei fell into two groups. One of these groups was very 

 closely related to, if not identical with, the Pf. ivhitmori strains. 

 It is important to note that the 2 strains of Pf. mallei which 

 resembled Pf. whitmori were isolated from ponies in Java and 

 India respectively ; since they differed in certain respects from 

 the other strains of Pf. mallei, which were isolated in England 

 and Egypt, it is just possible that they were variant strains of 

 Pf. whitmori. According to de Moor and his colleagues (1932), 

 strains of mallei and whitmori show cross-agglutination to titre, 

 and complete cross-absorption, with specific sera. Cross-allergic 

 reactions are also said to be obtainable in infected animals with 

 mallein and the corresponding product prepared from cultures 

 of Pf. ivhitmori. Verge and Pairemaure (1928) have reported 

 a positive complement-fixation reaction with the serum of a 

 glandered horse in the presence of a whitmori antigen. Further 

 work, however, is obviously desirable on the antigenic structure 

 and relationship of these two organisms. 



Pathogenically, Pf. mallei gives rise to disease in equines, 

 while Pf. whitmori is a natural parasite of rodents. Both 

 organisms can cause disease in man ; both are infective for 

 laboratory animals ; and both are able to call forth the Straus 

 reaction on intraperitoneal inoculation of male guinea-pigs. 



Experimental Reproduction of Glanders in Animals. — Experi- 

 mentally glanders may be reproduced in horses, asses, and mules 

 by feeding with cultures of Pf. mallei, and by subcutaneous 

 inoculation. Sheep and goats are easily infected, but cows and 

 pigs are said to be resistant. Of laboratory animals the guinea- 

 pig and the field mouse {Arvicola arvalis) are the most susceptible 

 to experimental inoculation ; rabbits and dogs are less so ; rats, 

 birds, and perhaps white mice, are comparatively resistant. 



Guinea-pigs. — Loeffler (1886) made 85 experiments on guinea-pigs, and every animal 

 developed the disease. Not all observers, however, are agreed on the uniform susceptibility 

 of the guinea-pig ; young animals seem to be more resistant than older ones. 



After subcutaneous inoculation of a small amount of a pure culture, an abscess develops, 

 which ulcerates in 5 days ; the regional glands break down and discharge pus. At this 

 stage the disease may become stationary or retrogress, but usually it advances. In the 

 second week hard nodular foci are palpable in the testicles and epididymis ; inflammation 

 of the tunica vaginalis occurs, and the testicle becomes fixed to the overlying skin ; finally 

 ulceration takes place with the discharge of purulent material. In female guinea-pigs 

 the mammae and labia may be inflamed. Swelling and inflammation of one or more joints 

 is very common, sometimes leading to abscess formation and ulceration. Nodules often 

 appear in the muscles, face, back, or beneath the periosteum of the bones. In about a 

 third of the animals nodules appear on the nasal mucosa, and crusts collect around the 



Fig. 93.— 



Pfeifferella 

 whitmori. 



Gelatin stab cul- 

 ture, 10 days, 

 20° C, show- 

 ing stratiform 

 liquefaction. 



