CHAPTER IX 

 OTHER INTESTINAL BACTERIA 



IT would be an obvious advantage if the evidence of 

 sewage contamination, furnished by the presence of 

 the colon group, could be reinforced and confirmed 

 by the discovery in water of other forms equally char- 

 acteristic of the intestinal canal. The attention of a 

 few 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. 



Significance of the Sewage Streptococci. 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 commonly 

 found grow feebly on the surface of ordinary nutrient 

 agar, producing faint transparent, rounded colonies, 

 but under semi-anaerobic 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. They are seen under 

 the microscope as cocci, occurring as a rule in pairs, 



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