CULTURAL CHARACTERISTICS 629 



later falls to the bottom of the culture vessel. Chains and capsulated diplo- 

 cocci are found on microscopical examination of these cultures. 



Liquid serum. The growth in this medium is very scanty and consists of 

 a small glairy deposit made up of diplococci and encapsulated cocci in chains. 



Agar. The growth consists of small rounded points which are at first 

 transparent but afterwards opaque and often have a streaky blue appearance, 

 resembling a culture of streptococci. 



Gelatin. On gelatin, small white opaque rounded points are formed similar 

 to colonies of streptococci : the medium is not liquefied. 



Milk. The growth in milk is very poor. Coagulation is not a constant 

 phenomenon. 



Potato. No apparent growth takes place on potato but a microscopical 

 examination of the scrapings of the surface of the medium will show that 

 there has undoubtedly been some multiplication. 



Vitality and virulence. In liquid media the enterococcus retains both its 

 vitality and virulence for a long time ; Thiercelin was able to sow sub-cultures 

 from a broth culture several weeks old, and Besson killed rabbits with a 

 culture which had been sub-cultivated six times in blood-broth : in anaerobic 

 culture the vitality is maintained for several years. The addition of appreci- 

 able traces of antiseptics (carbolic acid, etc,) does not hinder the growth of the 

 cultures. 



Toxins. The saprophytic enterococcus though incapable of infecting the rabbit 

 will nevertheless often kill the animal by toxaemia. Following an injection of culture, 

 the animal sickens and becomes cachectic, develops paraplegic symptoms and dies 

 on an average in a fortnight to 25 days. Post mortem large purulent lesions are 

 frequently found, but the only organisms present are organisms of secondary infection 

 (staphylococci, etc.). Sub-cutaneous inoculation of a culture of the saprophyte 

 filtered through a Chamber-land bougie leads to the death of the rabbit from cachexia 

 (Thiercelin and Jouhaud) : the same result is obtained with cultures which have 

 been sterilized by boiling for half an hour or by heating at 110 C. for 15 minutes. 

 The addition of iodine has no action on the cachexia-producing properties of the 

 toxin (Rosenthal and Charazain). 



SECTION III. DETECTION, ISOLATION AND IDENTIFICATION OP 

 THE ENTEROCOCCUS. 



A. The isolation of the enterococcus from pathological material is easy ; 

 a, small portion should be sown in broth both aerobically and anaerobically. 

 and the organism may then be isolated in the ordinary way on sloped agar 

 or on plates. The colonies of the enterococcus can be recognized by their 

 characteristic appearance, and may be picked off and sown in broth to obtain 

 pure cultures. 



Note. In pathological material the enterococcus, as has already been 

 stated, often closely resembles the pneumococcus and erroneous conclusions 

 may be drawn from microscopical examination if this fact be not borne in 

 mind. 



B. The isolation of the enterococcus from stools is more difficult on account 

 of the presence of other easily growing organisms : Thiercelin describes two 

 methods : 



(a) Dilute a trace of the stool in a tube of broth, filter through a double 

 layer of filter paper (the funnel and paper both being sterile) into a sterile 

 tube, and sow several agar-slope tubes with the filtrate. After incubating 

 for 24 hours, the tubes will show numerous colonies of the enterococcus : the 



