CHROMOBACTERIUM TYPHI-FLAVUM 639 



Agar Slope. — 24 hours at 37° C. Abundant, confluent, smooth, glistening, yellow, opaque 

 growth, with entire or shghtly undulate edge. 



5 per cent. Glycerine Agar Slope. — Growth similar to that on agar slope but very mucoid 

 in character. 



Agar Shake. — Yellow surface growth with a few small colonies throughout the medium. 



Agar Pour-Plate. — Deep colonies are biconvex, sometimes with lateral knobs or projections. 



Broth.- — 24 hours at 37° C. Uniform turbidity with a powdery white or yellowish deposit 

 easily dispersed on shaking. After 5 days, increased turbidity with a fine surface 

 scum or ring. 



Horse-blood Agar Plate. — No haemolysis. Colonies as on agar plate. 



MacConkeys Agar. — 24 hours at 37° C. Growth hardly perceptible. 6 days. — -Irregularly 

 round colourless colonies with a rough surface and crenated edge. 



Loeffler^s Serum Slope. — 24 hours at 37° C. Good, confluent, ghstening, yellow growth 

 with smooth or slightly contoured surface and undulate edge. No liquefac- 

 tion. 



Potato. — 3 days at 37° C. Abundant, confluent, yellow, glistening, mucoid growth. 



Gelatin Stab. — Ffliform growth along line of inoculation. After 6-10 days liquefaction 

 begins and progresses till the medium is entirely liquefied in the next 10-15 days. 

 Liquefaction is infundibuliform ; a yellow surface pellicle forms, and later sinks 

 to the bottom. 



Resistance. — ^Destroyed by 56° C. in 10 minutes. 



Metabolism. — Aerobic. Poor unpigmented growth anaerobicaUy. Grows freely at 

 20-37° C, with optimum nearer to 37° C. Pigment ochre or rusty-yellow, insoluble 

 in water and chloroform, partly soluble in alcohol and ether. 



Biochemical Reactions. — Acid in glucose, mannitol, sucrose, sahcin, rhamnose, arabinose, 

 xylose ; maltose usually later. Lactose, mositol and dulcitol not fermented. Litmus 

 milk neutral or transient acidity, becoming alkaUne after 3-7 days ; occasional soft 

 clot. Indole — . M.R. -|-. V.P. — . Nitrates reduced. Very slight HjS pro- 

 duction at 22° C. Catalase -|- . 



Antigenic Structure. — The organisms are antigenicaUy heterogeneous. Both as regards 

 flagellar and somatic antigens, sera prepared against any one strain will agglutinate 

 the homologous strain, and usually several other strains. There is a tendency 

 for the organisms to fall roughly into antigenicaUy similar groups, the H antigens 

 being more cosmopohtan than the 0. 



Pathogenicity. — It has been suggested that the organism is a variant of Salm. typhi, 

 of potential pathogenicity to man, but this has not been substantiated. Pathogenic 

 to mice only on injection of enormous doses. 



There are several organisms in water and in soil belonging to this group, amongst 

 which may be mentioned : 



Chr. ochraceum. — Motile by polar flagella. Infundibuliform liquefaction in gelatin 

 with a pale yellow, later ochre-coloured, deposit. On agar and potato a thin, ochre-yellow 

 streak. 



Chr. fuscum. — Non-motile ; liquefies gelatin slowly or not at all. On agar and potato 

 gives a thick, wrinkled, chrome-yellow growth. 



Chr. aurantiacum. — Motile by peritrichate flagella. No liquefaction of gelatin. On 

 agar and potato forms a light orange growth. 



Chr. denitriflcans. — Described by Bm-ri and Stutzer (1895), who isolated it from horse 

 faeces ; called by them B. denitrificans I. Appears to be common in the soil. Rods 

 with rounded ends, 1 ■5-2-5 /t X 0-75 /I. Actively motile. Gram-negative. Grows freely 

 on ordinary media, more quickly at 37° C. than at room temperature, and is aerobic. 

 Colonies on agar are very thin and membranous, having a thicker centre ; generally 

 circular, but may have a lobate or irregularly erose edge. In broth there is a dense 

 turbidity in 24 hours, with a reddish-white deposit disintegrating on shaking ; surface 



