400 ERYSIPELOTHRIX AND LISTERELLA 



of bacterial taxonomy to classify them in separate genera. Our proposal, there- 

 fore, is to include them both in the Erysipelothrix genus, calling them Ery. rhusio- 

 pathicB and Ery. monocytogenes respectively. It may be pointed out that in any 

 case the name Listerella is invalid, since it was given to a mycetozoan by Jahn 

 in 1906 (see Pirie 1940). 



Erysipelothrix rhusiopathiae 



Synonyms. — B. rhusiopathice suis Kitt ; Erysipelothrix porci Rosenbach ; B. erysipelatis 

 suis. 



Isolation. — Observed independently by Thuillier (Pasteur and ThuiUier 1883) and Loeffler 

 (1886) in 1882. 



Habitat. — Found on the mucosae and tonsils of swine. 



Morphology. — Smooth form. Small, slender, straight or slightly curved rods, 0-8-2-0 /n long 



and 0-3-0-4 fx broad. Arranged singly, in small packets, in small groups, or in 



short chains. Rough form. Long chains of baciUi and interlaced filaments of 



variable length. Staining is fairly regular, but sometimes deeply-stained granules 



' may be seen. Non-motile. Non-sporing. Gram-positive. 



. V ^ 





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^'^ . \ ' 



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A • \ 



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1 I 



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Fig. 66. — Erysipelothrix rhusiopathiee. 



Left : Smooth form. Right : Rough form. From a surface agar culture, 3 days, 37° C. 



(X 1000). 



Agar Plate.- — 24 liours, 37° C. Smooth form. Round, convex, tiny, amorphous, water- 

 clear colonies, 0-1 mm. in diameter, with smooth glistening surface and entire edge ; 

 butyrous and easily emulsifiable. No increase in size on further incubation. Rough 

 form. Rather larger and flatter, 0-2-0-4 mm. in diameter, with a granular curled 

 appearance and fimbriate edge ; resemble miniature anthrax colonies. 



Agar Slope. — 24 hours, 37° C. Very poor, partly confluent, shghtly raised, colourless, 

 transparent growth with an irregular svuface due to imperfect fusion of individual 

 colonies, and an edge which is very finely dentate or made up of single colonies. 



j Practically no change on fm-ther incubation ; growth may become shghtly 



viscous. 



Gelatin Plates. — Deep colonies in 3 or 4 days resemble snow-flakes ; they are very 

 small, but when magnified 50 times they are seen to consist of a granular centre 

 with branching threads radiating outwards. 



Gelatin Stab. — Growth occurs slowly and is subject to considerable variation, apparently 

 depending to some extent on the reaction of the medium. May be a simple 



