CHAPTER IX. 



OTHER INTESTINAL BACTERIA. 



It would be an obvious advantage if the evidence of 

 sewage contamination, furnished by the presence of B. 

 coli, could be reinforced and confirmed by the discovery 

 in water of other forms equally characteristic of the 

 intestinal canal. The attention of bacteriologists in 

 England and America has been turned in this direction 

 during the past few years; and two groups of organisms, 

 the sewage streptococci and the anaerobic spore-bearing 

 bacilli, have been described as probably significant. 



The term "sewage streptococci," as generally used, 

 covers an ill-defined group including many cocci which 

 do not occur in well-marked chains. Those most com- 

 monly found correspond rather closely to the type of 

 Str. pyogenes (identical with Str. erysipelatos). They 

 grow feebly on the surface of ordinary nutrient agar, pro- 

 ducing faint transparent, rounded colonies, but under 

 semi-anserobic conditions flourish better, giving a well- 

 marked growth along the gelatin stab and only a small 

 circumscribed film on the surface. They are favored by 

 the presence of the sugars and ferment dextrose and 

 lactose, with the formation of abundant acid but no gas. 



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