CHAPTER 32 

 PASTEURELLA 



Definition. — Pasteurella. 



Small, Gram-negative, ovoid bacilli, showing bipolar staining. Aerobic and 

 facultatively anaerobic. Powers of carbohydrate fermentation relatively slight ; 

 no gas produced. Gelatin not liquefied. Parasites in man and animals, producing 

 characteristic infections. 



The type species is Pasteurella aviseptica. 



Isolation. — The first member of this group was isolated by Kitt in 1878 from 

 an epidemic disease affecting wild hogs and deer. Similar organisms have been 

 isolated from several species of animals and birds suffering from a disease known 

 as hsemorrhagic septicaemia. It has become customary to give a specific name 

 to each organism, corresponding to the animal from which it was derived ; thus 

 we have Past, aviseptica from fowls, Past, lepiseptica from rabbits, Past, suiseptica 

 from pigs. Past, vituliseptica from calves. Past, oviseptica from sheep. Past, boviseptica 

 from cattle, and Past, muriseptica from mice (not to be confused with Erysipelothrix 

 muriseptica). Such a nomenclature is purely arbitrary, and is clearly unjustifiable 

 from the sytematic point of view. The differentiation of species within this group, 

 as in all others, must depend on the detailed study of an adequate sample of strains. 

 Such data as are available do not suggest that the strains from the various animal 

 species, which are liable to natural pasteurellosis, are themselves specifically dis- 

 tinct. In the description which follows we have taken Past, aviseptica as a type 

 of the hsemorrhagic septicaemia group ; but, as we point out in a later section, it 

 is doubtful whether this name will survive as a designation for a distinct species. 



Malassez and Vignal (1883) were apparently the first to describe pseudotuber- 

 culosis in the guinea-pig. Several workers recorded the finding of a bacillus in 

 this disease (see Chapter 73), chief amongst whom was Pfeiffer (1890), who 

 named it B. pseudotuberculosis. It is not to be confused with Corynebacterium 

 pseudotuberculosis ovis, described by Preisz and Nocard as the cause of pseudo- 

 tuberculosis in sheep (see Chapter 17), or with Corynebacterium pseudotuberculosis 

 murium, described by Kutscher (1894) and Bongert (1901) as the cause of pseudo- 

 tuberculosis in mice (see Chapter 17). 



The plague baciUus, Past, pestis, was isolated almost simultaneously by Kitasato 

 (1894) and by Yersin (1894), from human patients suffering from plague. 



These three organisms resemble each other in so many characters, and appear 

 to be 80 closely related, that they may well be considered as falling within a single 

 genus. 



Morphology and Staining.— All the members of the group are small, ovoid 

 bacilli, with convex sides and rounded ends ; there is no characteristic arrange- 



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