410 PATHOGENIC MICROORGANISMS 



Andrewes and Horder suggest the following classification: 



(1) Streptococcus pyogenes. Grows in long chains and ferments lactose, 

 saccharose, and salicin; does not coagulate milk. Streptococci which cause 

 suppurative lesions or severe systemic infections belong to this group. 



(2) Streptococcus mitis. A saprophytic type found frequently in the 

 mouth which shows the same cultural characteristics as the streptococcus 

 pyogenes, but grows in short chains. 



(3) Streptococcus anginosus. Found frequently in throats of scarlet-fever 

 patients which differs from the pyogenes only in coagulating milk. 



(4) Streptococcus salivarius. A short -chain type which ferments lactose, 

 saccharose, and raffinose, and coagulates milk. Streptococci of this type are 

 found frequently in the mouth, but are rarely pathogenic. 



(5) Streptococcus fecalis. A short-chain type which ferments lactose, 

 saccharose, and mannite. This type is found normally in the intestine, and 

 is occasionally pathogenic. 



(6) Streptococcus equinus. A short-chain type which does not ferment 

 lactose. Found in horse dung and never pathogenic. 



Quantitative determinations of the amount of acid formed in 

 various sugars by different races have also been made by Winslow 

 and Palmer 28 and others, but have led to no satisfactory classi- 

 fication. 



Studies by Hopkins and Lang seem to show that the streptococci 

 found in most human infections may be differentiated from the 

 ordinary saprophytic types by the fact that they ferment lactose 

 and salicin; but fail to ferment raffinose, inulin, or mannite. Accord- 

 ing to their results, the usual saprophytic types found in the mouth 

 either fail to ferment salicin or ferment raffinose or inulin, whereas 

 the usual fecal types ferment mannite. They also found in infection 

 mannite fermenters which were apparently of fecal origin. Strep- 

 tococci which gave the same fermentative reaction as the mouth 

 saprophytes were, however, frequently found in malignant endo- 

 carditis. 



Holman combined, or tried to combine classification by the Gor- 

 don carbohydrate fermentations and by the blood agar medium, 

 and somewhat simplified the difficulties. He recognized a hemolytic 

 and a non-hemolytic group under each of which he classifies eight 

 fermentative subgroups. The practical importance which lie at- 

 taches to his investigations is thai streptococci from similar sources 



28 Jour, of Inf. Dis., No. viii, 1910, 1. 



