610 THE STREPTOCOCCI OF MAN 



in acid perchloride or absolute alcohol and subsequently stained by Gram's 

 method (double or triple staining, p. 219). 



(6) Cultures. Blood should be sown in broth and on agar. 



p us . To isolate streptococci from pus when other organisms are present^ 

 sow a little of the material on three agar-slope tubes by the dilution method 

 (p. 82). In this way single colonies will be obtained. 



To isolate streptococci from a case of erysipelas : cleanse the skin, make 

 a prick with a lancet, and wipe away the first drop or two of blood with a 

 piece of sterile filter paper, then with the thumb and index finger pinch up 

 the skin on either side of the puncture, collect the fluid which wells up in a 

 Pasteur pipette and sow it in broth. 



(c) Animal inoculation. To determine the virulence of a streptococcus 

 either inoculate the material containing the organism directly into a rabbit ; 

 or, better, make a preliminary culture in broth or blood-broth, incubate at 

 37" C. for 2 days and then inoculate a rabbit. 



[Mice may, of course, be used instead of and are, in many w T ays, more 

 convenient than rabbits.] 



Meyer and Ruppel sowed material containing streptococci direct from various 

 human diseases (erysipelas, scarlet fever, inflammatory conditions, etc.) on to defibrin- 

 ated human blood and obtained cultures which were from the first virulent for 

 rabbits and mice: O'Ol -0'000,001 c.c. of these cultures was fatal to mice on intra- 

 peritoneal inoculation. 



Streptococcus of Bonome. 



Bonome isolated a streptococcus from the pus of cases of cerebro-spinal meningitis 

 and the same organism has since been found by Netter, Chantemesse, Bezan9on 

 and Griffon in many cases of epidemic meningitis. This streptococcus apparently 

 plays merely the part of a secondary infection in epidemic meningitis and indeed 

 has frequently been found associated with the meningococcus. 



According to Netter this organism is an attenuated variety of the pneumococcus : 

 well-marked differences however exist between the two organisms. The strepto- 

 coccus meningitidis appears to be very closely related to the streptococcus mucosu? 

 of Schottmiiller. 



Experimental inoculation. White mice are very susceptible ; after sub-cutaneous 

 inoculation they die in 24 hours of septicaemia. 'Rabbits are rather less susceptible 

 and guinea-pigs are as a rule refractory to sub-cutaneous inoculation. Intra-pleural 

 inoculation is fatal to white rats. After several passages through rats the organism no 

 longer forms chains but has the morphological appearance of the pneumococcus ( Netter ) . 



Microscopical appearance. The streptococcus of Bonome is an ovoid coccus 

 which forms short chains generally seen extra-cellularly and which in pus and serum 

 cultures shows a capsule. 



It is readily stained by the aniline dyes and is gram-positive. 



Cultures. This streptococcus grows easily on the ordinary media. Growth takes 

 place at 20 C. and consequently the organism can be grown on gelatin. The 

 optimum temperature is 37 C.-38 C. The vitality of the streptococcus of Bonome 

 is greater than that of the pneumococcus (Bezangon and Griffon). 



Broth. Sown in broth and incubated at 37 C. the streptococcus of Bonome 

 gives rise to a slight cloudiness in 24 hours and later to a minimal deposit. 



Gelatin. On gelatin at 22 C. the organism gives rise to a scanty growth of small 

 white opaque discrete points. The medium is not liquefied. 



Agar. A delicate growth of transparent colonies similar to those of the pneumo- 

 coccus is formed on agar on incubation at 37 C. 



Liquid rabbit serum. The culture on this medium is characteristic (Bezangon and 

 Griffon). After 24 hours' incubation at 37 C. there is a very slight cloudiness of 

 the medium and a little deposit. Under the microscope it will be found that the 

 growth consists of chains of variable length and of diplococci agglutinated in small 

 clumps. The capsules are delicate and shrivelled. 



Milk. Growth takes place and the medium is sometimes coagulated but often 

 unchanged. 



Potato. No apparent growth on potato. 



