Methodic aspects of microbiological water analysis

Summary

Ensuring the epidemic safety of the water use in relation to intestinal waterborne infections has been the main and high-priority task of the microbiological water quality control. The regulations in force have methodological differences in determining and identifying epidemiologically significant parameters the validity of which is of primary importance. Taking into account the urgency of the issue the methodological discrepancies of oxidase test procedure in determining total coliforms on Endo agar are considered. On the ground of experimental data a new procedure of differentiating coliforms from oxidase positive microorganisms like Pseudomonas, Aeromonas and other aquatic saprophytic bacteria is suggested. Chromogenic media are of great practical interest since they contain substances that inhibit the growth of gram-positive microbial flora that is abundant in natural water sources and produces a negative effect in identification of target microorganisms. In this respect possible use of Chromocult Coliform Agar ES chromogenic medium in sanitary-microbiological water analysis for total and thermotolerant coliforms and Escherichia coli is evaluated. An original color differentiation of the colonies growing on Chromocult Coliform Agar ES medium is suggested that requires additional tests only for separate colony types. The comparative analysis of Endo and Chromocult Coliform Agar ES media is given.

Key words

Escherichia coli , microbiological water analysis , oxidase test , Endo medium , chromogenic medium , Chromocult Coliform Agar ES , coliforms