Elements of water bacteriology : with special reference to sanitary water analysis / by Samuel Cate Prescott, and Charles-Edward Amory Winslow.

  • Prescott, Samuel Cate, 1872-1962.
Date:
1904
Catalogue details

Licence: In copyright

Credit: Elements of water bacteriology : with special reference to sanitary water analysis / by Samuel Cate Prescott, and Charles-Edward Amory Winslow. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    ferments saccharose with a gas ratio approaching —, and another does not. As a rule, a strong acid reaction is developed in all sugar-containing media. The or- ganism reduces nitrates to nitrites and sometimes to ammonia. It coagulates casein in Htmus milk, and reduces the litmus with subsequent slow return of the color (red), and forms indol in peptone solution. Many cukures of this organism are fatal to guinea-pigs when • the latter are inoculated subcutaneously with i c.c. of a twenty-four-hour bouillon culture, and most cultures produce death when this amount is inoculated intraperi- toneally. Akhough not a spore-forming bacillus, and in general not possessing great resistance against anti- septic substances, B. coli seems to be less susceptible to phenol than are many other forms, especially certain water-bacteria. The Wurtz litmus-lactose-agar plate (Wurtz, 1892), as noted in Chapter IV, furnishes one ready method for the isolation of B. coU from water, and it was used by Sedg- wick and Mathews for the purpose as early as 1893 (Mathews, 1893). The process is based upon the fact already alluded to, that B. coH readily ferments lactose with the formation of acid. If, therefore, plates are made with agar containing both lactose and litmus, the colon colonies develop as red spots in a blue field. Since or- ganisms other than B. coli may also develop red colonies, it becomes necessary further to examine the red colonies in order to prove that they are made up of colon bacilli.