SIMPLIFIED PROCEDURE FOR EXAMINATION OF DRINKING-WATER FOR BACTERIA OF PUBLIC-HEALTH SIGNIFICANCE - DIFFERENTIAL HYDRO-BACTERIOGRAM

  • 1 January 1977
    • journal article
    • review article
    • Vol. 165  (5-6) , 498-516
Abstract
A new method is described which can be used for the examination of piped drinking water. It is also suitable for monitoring water which was initially of potable quality, and is intended for reuse in the food industry. The method is based on Clark''s P-A [presence-absence] test and, because this allows many bacterial types to be detected, i.e., Enterobacteriaceae, Escherichia coli, Pseudomonas aeruginosa, Aeromonadaceae and Lancefield group D streptococci, it is called the differential hydrobacteriogram. A preliminary resuscitation treatment to revive sublethally injured cells is essential in this procedure. In earlier work this was attained by adding an equal volume of double strength nutrient broth and later double strength MacConkey purple broth, making the method somewhat bulky. In the new procedure, after the resuscitation step, a concentrated bile salts/indicator solution is added, allowing subsequent enrichment of the taxa sought. Positive enrichment cultures are examined for these organisms. The new method, when tested on approximately 150 artificially inoculated and 92 natural samples, showed the same productivity and selectivity as the 1 introduced earlier. The new method is recommended for routine monitoring purposes because it is less bulky.

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