Synopses & Reviews
Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III Bacteriology of Excreta in Relation to the Bacteriological Examination of Water The main object of the bacteriological examination of water is to ascertain whether sewage and excreta have gained access to it, directly or indirectly. It is, therefore, obviously of the utmost importance to have a knowledge of the organisms prevalent in excreta and of their relative abundance. While it is of value to have reliable data as to the presence in faeces of such specially pathogenic organisms as the bacilli of typhoid fever and dysentery, yet, as a means of detecting the presence of excreta in water-supplies, a knowledge of the organisms most numerous and widely prevalent in ordinary healthy stools is of far greater importance, since the detection of these in waters can serve as an indication of the presence of excreta. Houston (Houston, 1902-1903, a) examined seventeen normal stools of healthy persons. The average results obtained per gramme of faeces were as follows: Total number of bacteria (gelatine at 20 C., and agar at 37 C.) between 100 million and 1,000 million. Spores of aerobic bacteria between 1,000 and 10,000. B. coli between 100 million and 1,000 million. B. enteritidis sporogenes spores (based on milk test) between I million and 10 million, and about the same number of virulent organisms. Streptococci at least 100,000. In a subsequent report Houston remarks that later work leads him to regard this number of streptococci as probably an under-estimate, and he states that in some samples of fasces the streptococci may exceed the B. coli in number. Ninety-one per cent. of the streptococci formed short to medium chains in broth cultures, 81 per cent. produced clotting in milk, while practically all were either non- pathogenic to mice, or t...
Synopsis
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