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

Most significant sanitary microbiological parameters of drinking water quality assessment

Summary

Sanitary control of water is a complex and multilevel process. It is associated with every stage of water use, starting from the water supply source selection, monitoring, and water treatment to disinfection and wastewater disposal to collection facilities. Sanitary and microbiological water assessment implies determining sanitary profile, i. e. criteria that reflect compliance or noncompliance of the object under investigation with the regulatory documents requirements. The determined parameters and the frequency of their measurement depend on the assignment of the project under investigation and are strictly regulated by the respective regulatory framework. Sanitary parameters are divided into index parameters
that reflect the level of fecal pollution and indicator parameters that reflect the quality of water treatment. Index parameters include: Escherichia сoli, thermotolerant coliforms and coliphages. Indicator parameters are: total microbial count, total coliforms, sulfite-reducing clostridia spores etc. Determination of some pathogenic and opportunistic pathogenic bacteria like salmonella, pathogenic staphylococcus, blue pus bacillus etc. is an important aspect of water bodies monitoring. EC countries moved from determining groups of sanitary indicator microorganisms (thermotolerant coliforms, fecal staphylococcus, sulfite-reducing clostridia spores) to determining directly sanitary indicator microorganisms (Escherichia coli, Enterococcus faecalis, Clostridium perfringens), which makes water quality assessment more standardized and reliable. Advanced methods and approaches to the assessment of the sanitary state of the water bodies are continuously emerging and introduced in the international practice of sanitary surveys.

Key words

potable water , water quality , total coliform bacteria , sanitary index , index parameter , indicator parameter , Escherichia coli , thermotolerant coliforms , coliphages , total microbial count , salmonella , P. aeruginosa , S. aureus , sanitary microbiological assessment , sanitary indicator microorganism , chromogenic substratum