**1. Introduction**

Pathogen contamination of environmental waters is a major health risk and a threat to future supplies of water for living and recreational activities. Acceptable bacterial limits have been

© 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

defined in legislation by among others WHO [1], US EPA [2] and the European Union [3]. Health risks can be assessed and monitored using a series of tests for specific indicators which are defined in regional legislation. Water‐borne contamination and related diseases are discussed in detail elsewhere [4, 5]. A recent comprehensive review [6] considered recent reports on recreational water and infection comparing epidemiological studies and quantitative microbial risk assessment (QMRAs). While potential sources of contamination are considered in a review [7] which concentrates on the transport of pathogens in the agricultural setting and their health implications. In this chapter, we assess the methodology currently available for monitoring the presence of *Escherichia coli* in environmental waters. Although laboratory analyses will remain the reference procedures, the current trend is to develop onsite methodology which will yield more rapid results allowing more immediate action to be taken if contamination is found. This development also benefits, for example, developing countries where good laboratory procedures may not be easily accessible and accurate and reliable onsite technology will be the key to progress and improved public health.

waters. Another important aspect of faecal contamination of rivers and lakes is its effect on fish. This has both public health and economic impacts and is of critical importance in water bodies used for aquaculture [18–20]. The release of microorganisms into a lake or river and the use of antibiotics in fish farming can combine to create a perfect storm of an environment that is highly selective for the development of multi‐drug resistant strains. Effective monitoring of water quality and rapid detection of contamination as well as more sustainable approaches and a reduction of drug use in aquaculture will need to go hand-in-hand to improve food

In this chapter, the different procedures currently available for monitoring *E. coli* will be critically assessed and particular emphasis will be on comparing recent and older methods for the

Culture-based methods Sensitive, 1–2 days to obtain a result. Detects primary indicator organism and

Chromogenic agars Detects non‐viable VBNC as well as viable bacteria, based on the assay of β‐Dglucuronidase and β‐D-glucuronidase. API®ID Strip Range Based on miniaturised laboratory techniques used as confirmatory tests.

Membrane filtration method Reference method used for ISO standards. Culture on chromogenic media after

Most probable number Depends on growth of target organism in liquid medium, more time

Direct methods Direct measurement of indicator enzyme activity in water, usually using

Semi-automated methods Commercial procedures, e.g. Colilert analysers, use selective media and

Nucleic acid-based procedures Sensitive and rapid but when low numbers of bacteria are present and

Quantitative PCR qPCR determines the number of genomes per volume of water for a bacterial

pathogens, e.g. *E. coli* O157:H7.

usually requires enrichment step. qPCR and qPRT-PCR A rapid sensitive method used in study of emerging as well as established pathogens. Needs further standardisation. Biosensor techniques Able to directly detect target bacteria and provide real-time results. Portable

suitable for routine analysis.

**Table 1.** Established and developing methods used to monitor *E. coli* in environmental water.

filtration.

onsite monitoring.

others present, relies on biochemical or immunological methods of identification,

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

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

127

consuming and labour intensive than MFM, not suitable for marine organisms.

fluorescent substrates, suitable for online monitoring, can give results within 24 h.

enrichment step is needed. Invaluable technique to identify individual

species, can be coupled to fluorescence *in situ* hybridisation (FISH) or plate counting. FISH is used to identify different mixtures of bacteria in a sample,

and easy to use for onsite testing. Avoids cultivation step and can measure viable and non-viable cells. Sensitive optical biosensors can detect 7 cfu/ml *E. coli* in water samples. Biosensors based on electrochemical immunosensors are also used while biosensors based on physicochemical methods, e.g. Raman spectroscopy are currently under development but probably would not be

fluorescent substrates for β‐glucuronidase and β‐galactosidase. Suitable for

underestimates bacterial load as only viable organisms detected.

safety and environmental health.

detection *E. coli* (**Table 1**).

*E. coli* are present in the intestine of men and animals and are released into the environment in faecal material. As faecal matter is the main source for disease‐causing agents in water, faecal bacteria are widely used as indicators of contamination which can affect rivers, sea beaches, lakes, ground water, surface water, recreational water and the many and diverse activities associated with these [5]. Contamination can result from leakage of sewage, sewer overflow caused by storm events and accidental or deliberate release into receiving water bodies, as well as water draining from agricultural land or directly from livestock and birds [4, 8]. Sewage treatment plants can also be a source of pathogenic *E. coli* and these can spread in the river systems [9, 10]. Even low levels of contact with contaminated water in rivers [11] or beaches [12] are significant and can result in outbreak of gastroenteritis. However, the amount of water likely to be ingested is most important when determining the risk of certain activities (e.g. swimming, boating) [13]. Although coliforms do not usually cause serious illness they are used to indicate the presence of more pathogenic bacteria and viruses. The health risk to humans and animals can be assessed using a series of tests which are defined in regional legislation. Coliforms and in particular *E. coli* are the most valuable markers. *E. coli* is widely accepted as the better faecal indicator organism than total coliforms. Contamination of water supplies by pathogenic strains like *E. coli* O157:H7 is more serious but usually localised. A number of reports have shown that most *E. coli* (over 95%) express β‐D‐glucuronidase (GUD) activity [14] making this enzyme a sensitive and specific marker for *E. coli* detection and thus faecal pollution. The current acceptable upper limit for *E. coli* content in fresh surface water is 900 cfu/100 ml and 500 cfu/100 ml in marine water [3]. Although *E.coli* is the marker of choice a number of other markers are used in environmental monitoring. *Enterococci* for example are used as a maker for contamination particularly in marine waters [15]. Further details of other markers used in environmental monitoring are detailed in Price and Wildeboer [16].

The widespread use of antibiotics in agriculture and their release from sewage works has accelerated the development of antibiotic-resistant strains in environmental water bodies increasing the need for accurate and regular monitoring. A recent study [17] demonstrated the presence of bacteria resistant to a number of antibiotics, some of which were of faecal origin highlighting concerns about release and spread of antibiotic-resistant organisms in receiving waters. Another important aspect of faecal contamination of rivers and lakes is its effect on fish. This has both public health and economic impacts and is of critical importance in water bodies used for aquaculture [18–20]. The release of microorganisms into a lake or river and the use of antibiotics in fish farming can combine to create a perfect storm of an environment that is highly selective for the development of multi‐drug resistant strains. Effective monitoring of water quality and rapid detection of contamination as well as more sustainable approaches and a reduction of drug use in aquaculture will need to go hand-in-hand to improve food safety and environmental health.

defined in legislation by among others WHO [1], US EPA [2] and the European Union [3]. Health risks can be assessed and monitored using a series of tests for specific indicators which are defined in regional legislation. Water‐borne contamination and related diseases are discussed in detail elsewhere [4, 5]. A recent comprehensive review [6] considered recent reports on recreational water and infection comparing epidemiological studies and quantitative microbial risk assessment (QMRAs). While potential sources of contamination are considered in a review [7] which concentrates on the transport of pathogens in the agricultural setting and their health implications. In this chapter, we assess the methodology currently available for monitoring the presence of *Escherichia coli* in environmental waters. Although laboratory analyses will remain the reference procedures, the current trend is to develop onsite methodology which will yield more rapid results allowing more immediate action to be taken if contamination is found. This development also benefits, for example, developing countries where good laboratory procedures may not be easily accessible and accurate and reliable

*E. coli* are present in the intestine of men and animals and are released into the environment in faecal material. As faecal matter is the main source for disease‐causing agents in water, faecal bacteria are widely used as indicators of contamination which can affect rivers, sea beaches, lakes, ground water, surface water, recreational water and the many and diverse activities associated with these [5]. Contamination can result from leakage of sewage, sewer overflow caused by storm events and accidental or deliberate release into receiving water bodies, as well as water draining from agricultural land or directly from livestock and birds [4, 8]. Sewage treatment plants can also be a source of pathogenic *E. coli* and these can spread in the river systems [9, 10]. Even low levels of contact with contaminated water in rivers [11] or beaches [12] are significant and can result in outbreak of gastroenteritis. However, the amount of water likely to be ingested is most important when determining the risk of certain activities (e.g. swimming, boating) [13]. Although coliforms do not usually cause serious illness they are used to indicate the presence of more pathogenic bacteria and viruses. The health risk to humans and animals can be assessed using a series of tests which are defined in regional legislation. Coliforms and in particular *E. coli* are the most valuable markers. *E. coli* is widely accepted as the better faecal indicator organism than total coliforms. Contamination of water supplies by pathogenic strains like *E. coli* O157:H7 is more serious but usually localised. A number of reports have shown that most *E. coli* (over 95%) express β‐D‐glucuronidase (GUD) activity [14] making this enzyme a sensitive and specific marker for *E. coli* detection and thus faecal pollution. The current acceptable upper limit for *E. coli* content in fresh surface water is 900 cfu/100 ml and 500 cfu/100 ml in marine water [3]. Although *E.coli* is the marker of choice a number of other markers are used in environmental monitoring. *Enterococci* for example are used as a maker for contamination particularly in marine waters [15]. Further details of other markers

onsite technology will be the key to progress and improved public health.

126 *Escherichia coli* Escherichia coli - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications

used in environmental monitoring are detailed in Price and Wildeboer [16].

The widespread use of antibiotics in agriculture and their release from sewage works has accelerated the development of antibiotic-resistant strains in environmental water bodies increasing the need for accurate and regular monitoring. A recent study [17] demonstrated the presence of bacteria resistant to a number of antibiotics, some of which were of faecal origin highlighting concerns about release and spread of antibiotic-resistant organisms in receiving In this chapter, the different procedures currently available for monitoring *E. coli* will be critically assessed and particular emphasis will be on comparing recent and older methods for the detection *E. coli* (**Table 1**).


**Table 1.** Established and developing methods used to monitor *E. coli* in environmental water.
