The Significance of Faecal Indicators in Water: A Global Perspective
Comparison of Rapid Methods for Active Bathing Water Quality Monitoring
Published:28 Mar 2012
A. Henry, G. Scherpereel, R. Brown, J. Baudart, P. Servais, and N. Charni Ben Tabassi, in The Significance of Faecal Indicators in Water: A Global Perspective, ed. D. Kay and C. Fricker, The Royal Society of Chemistry, 2012, pp. 72-83.
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The recent European Directive (2006/7/CE) required member states to improve bathing water quality by reducing the sanitary risk for users. To be in agreement with the 2006 Directive expectations, actions need to be implemented to prevent, reduce or eliminate faecal pollution sources.
In Europe, the culture-based reference methods used to evaluate bathing water quality (i.e. the ISO 9308-3 and ISO 7899-1 methods, which require 2 days analysis) do not allow active management of bathing areas as recommended by the 2006 Council Directive. Therefore, rapid methods for efficient Escherichia coli (E. coli) enumeration in recreational waters are needed. Anticipating this approach, we developed and used, since 2006, the rapid method Coliplage® based on the detection of the specific E. coli β-D-Glucuronidase activity for active management of bathing water, as a complement to the official analyses. Nevertheless, for some identified bathing water types, discrepancies were observed between the reference method (ISO 9308-3) and the Coliplage® method. Thus, other technologies or tools proposed for water monitoring were evaluated with the objective of answering the question, “Which method for what application?” Four alternative methods, including one method based on direct enzymatic detection (i.e. Coliplage®), one molecular method based on the real-time quantification of E. coli by PCR and two automated culture-based methods (coupled with signal detection by impedance measurement and enzyme activity measurement) were compared in the study. We evaluated the effectiveness and relevance of each of them (in terms of specificity, sensitivity, analysis time, viability, cost, ease of implementation), to determine their applicability for the bathing sites studied, according to the 2006 European Council Directive.
In conclusion, enzymatic based methods (without culture) such as Coliplage® appear to be the most appropriate method to detect E. coli contamination in less than one hour and to provide an active management tool for faecal pollution.