400 THE COLON BACILLUS 



bered that a strain of the typhoid bacillus which is not agglutinated by a 

 typhoid serum may very occasionally be encountered. 



SECTION IV. DETECTION, ISOLATION AND IDENTIFICATION. 



The methods of detecting the colon bacillus in the tissues and fluids of the 

 body are similar in principle to those employed for the detection of the typhoid 

 bacillus. These methods as well as the differentiating tests, etc. are fully 

 dealt with in Chap. XXIII. 



It must be remembered that the colon bacillus often multiplies in the 

 body immediately after death, and even during the last few hours of life : 

 the finding of the colon bacillus in the tissues or fluids under these conditions 

 is therefore of no diagnostic value whatever. 



The bacillus of Green Diarrhoea. 



According to Lesage and Thiercelin the bacillus of green diarrhoea is merely a 

 chromogenic variety of the colon bacillus. The organism is found in practically 

 pure culture in the stools of children suffering from the disease. 



Experimental inoculation. The organism is only slightly pathogenic for laboratory 

 animals. Rabbits, when inoculated intra-venously or fed with cultures of the bacillus, 

 suffer from an attack of green diarrhoea from which they recover in a few days. 



Microscopical appearance. Morphologically the bacillus is a short rod-shaped 

 organism with rounded ends in every way similar to the colon bacillus. 



Cultures. The bacillus of green diarrhoea is a facultative aerobe. It grows on 

 all the ordinary media and gives rise to a disagreeable odour. The green colouring 

 matter is only produced in aerobic culture. 



A pure culture is very easily obtained by plating a trace of the stool of an infected 

 child on gelatin. 



Broth. At first the medium is uniformly cloudy but later a greenish sediment 

 is deposited. 



Gelatin is not liquefied. In stab culture, the bacillus gives rise to a scanty whitish 

 growth in the substance of this medium and on the surface to a smalf greenish 

 lenticular pellicle. On sloped gelatin, the growth is poor, greenish in colour and has 

 a tendency to spread away from the line of sowing : after a few days the gelatin is 

 tinted uniformly green. Isolated colonies form small greenish granular points. 



On agar. The growth is poor, greenish in colour and spreading. The agar acquires 

 a green tint. 



On potato. The growth is luxuriant, covers the whole surface of the medium 

 and is of a dirty green mucous appearance. 



M ilk is rapidly coagulated. 



Carbohydrate media are strongly fermented. 



