BRUCELLA ME LIT EN SIS 



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TABLE 53 

 Classification of Brucella Group 



Brucella melitensis 



Synonyms. — M. melitensis, Alkaligenes melitensis. 



Isolation.— Isolskted by Bruce (1887) from the spleen of patients dying of Malta 

 fever. 



Habitat. — Strict parasite living in goats, sheep and man. 



Morphology. — Small bacilli, 0-6-1 -2 fi long X 0-5-0-7 /n broad, coccoid forms abundant. 

 Axis straight, ends rounded, sides bulging or parallel. Arranged singly, in pairs 

 end-to-end, in small groups, or — especially in liquid media — in short chains of 

 four to six members. Non-motile. Bipolar staining not uncommon. Gram- 

 negative. 



Agar Plate. — 48 hours at 37° C. Small, round, convex, amorphous colonies about 0-5 

 mm . in diameter. Smooth, glistening surface, entire edge, translucent, greyish-white 

 by reflected light, almost colourless by transmitted light ; consistency butyrous ; 

 emulsification easy. 6-day colonies slightly larger, and greyish-yellow. No 

 differentiation. 



Agar Stroke. — 48 hours at 37° C. Poor to moderate, partly confluent, slightly raised, 

 translucent growth, with pitted surface, and edge formed of single colonies. After 

 a week the agar is turned brownish and crystals may appear. 



Gelatin Stab. — 10 days at 22° C. Poor to moderate, filiform, greyish-white growth, con- 

 sisting of very small colonies closely packed ; extends to bottom of tube. No 

 surface growth and no liquefaction. 



Broth. — 24 hours at 37° C. Poor growth with slight turbidity ; no surface growth and 

 no deposit. After 10 days there is an abundant growth with moderate turbidity, 

 and a moderate powdery deposit disintegrating completely on shaking. Later the 

 deposit becomes very viscous, and almost impossible to disintegrate. 



Loeffler^s Serum. — 48 hours at 37° C. Moderate, slightly raised, chiefly confluent growth 

 of yellowish colour. No liquefaction. 



Potato. — 6 days at 37° C. Thin, mostly confluent growth of greyish-brown colour. After 

 14 days the growth has a cafe-au-lait or chocolate colour. 



Shake Agar. — 4 days at 37° C. Growth of tiny, discrete colonies, situated at the surface, 

 or some distance below the surface ; exact position depends on the COg-sensitivity 

 of the strain. 



Liver Agar Plates containing Dyes. — 3 days at 37° C. Usually some growth in presence of 

 thionin, basic fuchsin, methyl violet, and pyronin, but reaction varies considerably 

 according to source of origm of strain. 



MacConkey Agar Plate.— 1 days at 37° C. Small, circular, convex, amorphous, yellowish 

 colonies, 0-1-1 -0 mm. in diameter, with smooth surface and entire edge. May 

 appear slightly mucoid. 



