586 STREPTOCOCCUS 



broth containing 1 : 15,000 potassium tellurite, and on lactose agar at a pH of 9-6 

 or containing 6-5 per cent. NaCl. It may be noted that Str. fcecalis possesses the 

 unusual property among streptococci of being insensitive to penicillin (Fleming 

 1932). It seems to us very doubtful whether any other members of this group 

 can be assigned specific rank, and we should agree with Shattock and Mattick 

 (1943) in regarding for the present the zyrnogenes, liquefaciens and durans organisms 

 as varieties of Str. fcecalis. Str. glycerinaceus has no claim even to a varietal 

 name. The position of Str. bovis must await further observations. 



Within the enterococcus group an attempt has been made to distinguish antigenic 

 types, but so far Uttle progress has been made. Lancefield (1941) states that she has 

 been able to define three types, differing apparently in the nature of their polysaccharide 

 antigen ; and Grumbach and Schnetz (1938) claim to have distinguished seven types by 

 agglutination. Whether these types occur within the species Str. fcecalis as we have 

 defined it, or correspond to any of its varieties, it is at jjresent impossible to say. 



Group E. 



The few strains belonging to this antigenic group were isolated from cows' milk by 

 Lancefield (1933). In view of the small number of strains examined, it is too early to 

 give any generaUzed description of the other grouiJ characters. Lancefield (1941) has 

 recognized one antigenic type. 



Group F. 



This group has been differentiated by Lancefield and Hare (1935) and by Hare (1935). 

 It possesses a characteristic group-specific polysaccharide antigen, by means of which it 

 may be identified. BUss (1937) has established four antigenic types by the use of precipita- 

 tion and agglutination tests. 



Group F strains grow slowly on blood agar plates, forming minute pin-point trans- 

 parent colonies siu-rounded by a narrow zone (1-5-1-8 mm. in diameter) of /^-haemolysis. 

 They are identical with the strains described by Long and Bliss (1934) as " minute hsemo- 

 lytic streptococci ". They do not, when tested by the usual methods, form a filtrable 

 hsemolysin acting on horse blood, but according to Plummer (1941) they do form a filtrable 

 hsemolysin for sheep blood. 



Group F strains produce a final acidity in glucose broth of pH 4-8-5-2. They do not 

 hydrolyse sodium hippurate. They do not reduce methylene blue in milk. They do 

 not grow either on 10 per cent, or on 40 per cent, bile agar. Some, but not all, strains 

 ferment trehalose, none ferments sorbitol. All that have been tested ferment lactose 

 and salicin. 



The strains that have been identified as belonging to this group have been derived 

 mainly from the human throat. There is some evidence that they may be responsible 

 for occasional cases of tonsiUitis, and perhaps for other infections of the respiratory tract. 



The provisional label for this group is clearly " Group F haemolytic strepto- 

 cocci," with a proviso that we are not insisting on the demonstration of the forma- 

 tion of a filtrable haemolysin before admitting a streptococcus to the heemolytic 

 class. 

 Group G. 



The strains of this group share a common group-specific polysaccharide antigen (Lance- 

 field and Hare 1935, Plummer 1935, Lancefield 1941). Hare (1935) notes that some 

 sera produced by the injection of Group C strains tend to give cross-precipitation with 

 extracts from Group G strains — a circumstance that appears to be due to their possession 

 of a common protein antigen (Lancefield 1941). Organisms from matt colonies of Groups C 

 and G strains resemble each other in fermenting trehalose but not sorbitol, and in pro- 

 ducing fibrinolysin and streptolysin 0. A number of antigenic types have been dis- 



