*E. coli* **as an Indicator of Contamination and Health Risk in Environmental Waters**

Robert G. Price and Dirk Wildeboer

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/67330

### **Abstract**

Good public health depends on regular monitoring of water quality as faecal contamination is a serious problem due to the potential for contracting disease. Bacterial contamination in water is measured using indicator organisms, notably *Escherichia coli and Enterococci* which are used as primary indicators of contamination in fresh and marine water quality, respectively, rather than the total coliforms present. Although most *E. coli and Enterococci* strains cause only mild infections, their presence is indicative of the potential presence of other more pathogenic organisms which are a danger to human health. The acceptable levels of indicator organisms are defined in legislation and are set for drinking, river, well and marine water. This chapter will consider current gold standard culture methods of analysis for *E. coli* and compare them with molecular DNA procedures. Established culture methods use β‐D-glucuronidase to identify *E. coli* and β‐D-galactosidase to detect coliforms. Emphasis will be placed on newer procedures that can be used onsite supported by laboratory procedures used for confirmation. Available rapid fluorimetric procedures which have been developed for use in the field, based on the assay of β‐D-glucuronidase, will be discussed. The rapid advances in procedures using a molecular approach will be considered and compared with the more established methods for determining *E. coli* in water. It is essential that all these methods should be quantitative in order to comply with legal norms, and in this regard, the potential involvement of biosensor technology will be of great value in successfully transferring laboratory procedures to the field.

**Keywords:** water quality monitoring, *E. coli*, β‐D‐glucuronidase, faecal bacteria, rapid detection of contamination, biosensors
