638 



CHROMOBACTERIU M 



Agar Plate. — 2 days at 25° C. Round colonies, 1-2 mm. in diameter, low convex, opaque, 

 yellowish-grey colour, with a dull, dry, granular or rugose surface, and an entire 

 edge ; consistency slightly membranous but emulsification fairly easy. After 5 

 days, colony shows differentiation into finely granular, yellowish-brown, convex 

 centre, and a clear almost transparent, effuse, and sometimes radiate periphery 

 which has an erose or villous edge. 



Agar Slope. — Abundant, confluent, opaque, yellowish, raised growth, with smooth glisten- 

 ing surface and a lobate or villous edge. 



Broth. — 2 days at 25° C. Shght turbidity, with slight powdery deposit. After 5 days 

 the growth is more abundant ; there is a very slightly granular turbidity, and 

 sometimes a surface pellicle and ring growth ; moderate membranous deposit, 

 disintegrating incompletely on shaking. 



Gelatin Stab.— 5 days at 20° C. Good growth, extending to bottom of tube ; gelatin 

 shows commencing infundibuhform liquefaction ; the liquefied gelatin shows a 

 floccular turbidity, and is covered with a granular peUicle. 



Potato. — 6 days at 25° C. Abundant, slightly raised, confluent, greyish-brown growth, 

 with a dry, dull, worm-cast surface. 



Loefflers Serum. — 5 days at 25° C. Good, confluent, raised, yellowish-white growth, with 

 wrinkled surface. 14 days, partial digestion. 



Metaholism.—^tviGi aerobe ; no growth under anaerobic conditions. Yellow pigment 

 formed on agar, soluble in alcohol, ether, and chloroform, but insoluble in water. 

 Optimum temperature for growth 25-30° C. 



Biochemical Characters. — Acid in glucose, maltose, mannitol, and sucrose. L.M. clot, 

 peptonization, and partial decolorization in 3 days. Indole — . M.R. — . V.P.-)-. 

 Nitrates reduced to nitrites. NHjsl. -]-. HjS-j-- M.B, reduction -[-. Catalase-[-. 



Pathogenicity. — Nil. 



Chromobacterium typhi-flavum 



Synonym. — Bacterium typhi flavum (Dresel and Stickl 1928). 



Habitat. — Air, grass, plants. Has been found in normal human faeces and urine. 

 Morphology. — Slender, rod-shaped organism, 1-3 [x x 0-5-0-7 /i : axis straight, sides 

 parallel, ends rounded ; sometimes filaments up to 15-20 ft in length ; arranged 



singly, in pairs end-to-end or in groups ; in fluid 

 media sausage-hke aggregations may occur. Briskly 

 motile when grown at 22° C, but poorly or not at 

 aU at 37° C. Flagella peritrichate. Non-sporing. 

 Non-capsulated. Gram-negative ; occasional bi- 

 polar staining. Non-acid-fast. 

 Agar Plate. — 24 hours at 37° C. Ready growth of colonies 

 1-2 mm. in diameter, round, low convex, amor- 

 phous, smooth, ghstening, opaque, with entire edge ; 

 consistency butjrrous, emulsifiabihty easy. Ochre 

 or rusty yellow pigment, not diffusing into the 

 medium. 



5 days. — Colonies are larger, 2-4 mm., differ- 

 entiated frequently into a central plateau, often 

 with a granular surface, and a smooth bevelled 

 periphery ; edge sometimes crenated. 



In the centre of the colonies aggregated masses 



with radiating extensions of a granular nature, or 



biconvex bodies with a clear-cut margin, may often 



be seen with the lens by transmitted hght. The 



granular structures are aggregations of organisms, known to the German workers 



as Bakterien-verbdnden or symplasmata (Fig. 133). The biconvex bodies represent 



downgrowths of the colony into the medium. 



Fig. 133. — Chromobacterium 

 typhi-flavum. 



Surface growth on agar plate, 

 showing the peculiar appear- 

 ance caused by aggregations 

 of the bacteria. One bicon- 

 vex bodv is clearly visible. 

 24 hours, 37° C. 



