304 
THE STREPTOCOCCUS-PNEUMOCOCCUS GROUP 
consisting of long chains of organisms is characteristic but not dis- 
tinctive of many virulent strains (Streptococcus conglomeratus) ; a 
granular sediment usually contains short-chain streptococci almost 
exclusively.^ 
Streptococcus pyogenes ferments glucose, mannose, fructose, galac- 
tose, lactose, maltose and saccharose, salicin and sorbitol, with the 
formation of considerable amounts of acid. Many strains do not 
ferment mannitol; very few cultures ferment inulin.- Milk is usually 
coagulated in from three to five days, the coagulum resulting from the 
accumulation of the acid fermentation of the lactose. The coagulum 
is never dissolved. Andrews and Horder^ state that Streptococcus 
pyogenes does not coagulate milk, although the organism produces 
a considerable amount of acid in this medium. Smith and Brown^ 
have shown that boiling the milk may be necessary to make the 
coagulum visible. 
Streptococci are bile-insoluble. 
Streptococcus pyogenes is an aerobic, facultatively anaerobic organ- 
ism. Pathogenic strains do not, as a rule, grow below 16° to 18° C, 
The optimum temperature lies between .35° and 39° C, the maximum 
about 44° C. The parasitic types are not long-lived away from the 
human body. Exposure to 60° C. for one hour will kill most strepto- 
cocci; a longer time is required if the organisms are exposed in albumin- 
ous media. Five per cent carbolic acid and 1 to 1000 mercuric chloride 
will kill the naked germs in from five to ten minutes. Streptococci 
dried in sputum will resist a temperature of 100° C. (in flowing steam) 
for several minutes, and drying at ordinary temperatures in the dark 
for several weeks. Direct sunlight kills them in about ten hours. The 
organisms survive and retain their virulence if they are suspended in 
sterile, defibrinated blood and kept in the ice-box for several weeks. 
Classification of Streptococci.— Holman^ has divided streptococci into 
a number of groups based upon their reaction in certain carbohydrates 
and upon blood. These groups are convenient and fairly representa- 
tive of the grosser varieties of streptococci commonly met with. 
Hemolysis. 
Lactose. 
Mannitol. 
Salicin. 
Habitat. 
S. pyogenes . . 
+ 
+ 
+ 
Nose, throat, blood. 
S. anginosus . 
+ 
+ . 
" 
" 
Nose, scarlet fever, endo- 
carditis, epidemic sore 
throat, septicemia. 
S. viridans 
- 
+ 
— 
+ 
Nose, throat, endocardi- 
tis, rheumatism. 
S. fecalis . . 
+ 
+ 
+ 
Feces, milk, rheumatism, 
endocarditis. 
S. salivarius 
+ 
— 
— 
Throat, mUk, pyorrhea. 
S. mucosus 
=*= 
+ 
? 
? 
1 See, however, the work of Cowan (ref. 4, p. .'^02^. 
2 Kendall, Day, Walker and Ryan: Jour. Infec. Dis., 1919, 25, 189. 
■^ Lancet, 1906, ii, 708. « Jour. Med. Res., 1914, 31, 455. 
5 Ibid., 1916, 34, 377. 
