FAMILY LACTOBACTli^RIACEAE 



321 



7. Streptococcus mitis Andrewes and 

 Herder. (Lancet, 2, 1906, 712.) From 

 Latin mitis, mild. 



Synonyms : Streptococcus mitior sou 

 viridans Schottmiiller, Mlinch. med. 

 Wchnachr., 50, 1903, &19 (these names 

 refer to a group of species and they are 

 therefore confused in meaning in medical 

 literature. See Winslow and Winslow, 

 The Systematic Relationships of the Coc- 

 caceae. New York, 1908, and Safford, 

 Sherman and Hodge, Jour. Bact., 33, 1937, 

 263). The name Streptococcus mitis was 

 first proposed by Frankel (Miinch. med. 

 Wchnschr., 52, 1904, 548 and 1868) . Be- 

 cause others have used this name with 

 varied meanings (Streptococcus mitis seu 

 viridans von Lingelsheim, in Kolle and 

 Wassermann, Handb. d. path. Mikroorg., 

 2 Aufl., 4, 1912, 453; Streptococcus mitis 

 Holman, Jour. Med. Res., 34, 1916,377), 

 the more definite emendation of An- 

 drewes and Horder has been used as the 

 basis of the description given here. The 

 relationships of these organisms has been 

 discussed by Brown, Rockefeller Inst. 

 Med. Res., Monograph No. 9, 1919, 86. 



Description based on studies by Saf- 

 ford, Sherman and Hodge {loc. cit.) and 

 Sherman, Niven and Smiley, Jour. Bact., 

 45,1943,249. 



Spherical or ellipsoidal cells, 0.6 to 0,8 

 micron in diameter. Long axis of cell lies 

 in axis of chain. Cells not especially 

 large in liquid media including milk. No 

 capsules. Gram-positive. 



Gelatin stab: Filiform growth. No 

 liquefaction. 



Nutrient agar : Growth increased when 

 serum or blood is added. Confluent 

 growth, gray and abundant. 



Action on blood agar : The colonies are 

 surrounded by a characteristic greening 

 (alpha hemolysis of Brown, Rockefeller 

 Inst. Med. Res., Monograph 9, 1919, 8). 

 This is weak with some strains and is 

 variable under anaerobic conditions. No 

 soluble toxin and no hemolysin has been 

 demonstrated. 



Broth : Variable. Loose, flocculent de- 



posit with clear supernatant fluid and 

 long chains, or granular turbidity with 

 small deposit and short chains. No 

 pellicle. 



Litmus milk : Usually acidified and 

 curdled promptly; litmus is completely 

 reduced but only after curdling; no di- 

 gestion. 



Potato : Slight growth which is difficult 

 to detect. 



Acid from glucose, maltose, lactose, 

 sucrose and usually salicin. Variable 

 fermentation of raffinose. No acid from 

 inulin, mannitol, sorbitol, glycerol, arabi- 

 nose or xylose. Trehalose rarely fer- 

 mented . 



No hydrolj'sis of sodium hippurate and 

 usualh^ no hydrolysis of arginine. Action 

 on esculin usually negative. 



Usually ammonia is not produced from 

 peptone. 



Chemical tolerance : Tolerates 2 per 

 cent but not 4 per cent NaCl. Final pH 

 in glucose broth 5.8 to 4.2, ave. 4.5. No 

 growth at pH 9.6. Methylene blue 0.01 

 per cent and 0.1 per cent not tolerated. 

 Not soluble in bile but inhibited by 30 

 per cent bile in blood agar. 



Catalase not produced. 



Temperature relations : Optimum 

 growth 37° to 40°C. Many strains do not 

 grow at 45°C. No growth at 10°C. Does 

 not survive 60°C for 30 minutes. 



Facultative anaerobe. 



Serology: No group antigen has been 

 demonstrated. Contains several sero- 

 logical types. 



Source: Saliva and sputum in various 

 pulmonary infections, pus from upper 

 respiratory tract and sinuses, blood and 

 various organs in sub-acute endocarditis. 



Habitat : Human mouth, throat and 

 nasopharynx. 



8. Streptococcus bovis Orla-Jensen 

 emend. Sherman. (Orla-Jensen, The 

 Lactic Acid Bacteria, 1919, 137; Sherman, 

 Bacteriological Reviews, 1, 1937, 57.) 

 From Latin hos, cow. 



The majority of the strains of Strepto- 



