2.2 Beach Water Pollution
Beaches across the USA are regularly monitored for FIB to protect the public from
waterborne diseases associated with fecal contamination, as required by the
Beaches Environmental Assessment and Coastal Health (BEACH) Act [45,
46]. When FIB concentrations exceed regulatory standards, swimming advisories
are issued and beaches may be closed to recreational use. Closed beaches lead to
frustration for beachgoers and substantial economic losses for associated communities. To protect public health, regulatory officials and beach managers need fast
and reliable tests for analyzing the bacteriological quality of beach waters. To meet
this need, a qPCR method for enterococci is now available as a rapid analytical
USEPA-approved tool for testing beach water quality. Test results can be obtained
in 2–4 h as compared to 18–24 h for conventional culture-based methods [23, 47,
48]. A second benefit is that deployment of a qPCR-based protocol for Enterococcus enumeration makes it relatively easy to use a qPCR-based MST marker for
human-source contamination. This second source-specific assay could be run either
in tandem or as a same-day follow-up to enterococci counts that were determined to
exceed the regulatory standard earlier in the day [6]. Similar to watersheds, a
variety of sources of fecal pollution potentially exist at recreational beaches. It is
therefore important to place the highest priority on evaluating whether human fecal
pollution contributes significantly to the FIB load, as human fecal material contains
a greater number of human pathogens and represents the greatest potential health
threat.
3 Microbial Source Tracking Methods
3.1 Library-Dependent Approach
Throughout the history of MST development, two basic strategies for host identification have been employed. Many early studies used a library-dependent approach
that involves constructing a database of FIB isolate types from known fecal sources
[19, 49]. Typing of indicator bacteria can be done in a variety of ways, including
antibiotic resistance [50, 51], carbon source utilization [52], or genetic diversity
[53, 54]. Isolates of FIB from water samples can then be similarly typed and
classified to a particular source by referencing the library. While this approach
showed some early success and is abundant in the literature, it is not currently
recommended for general application. Initial construction of the reference library is
costly, and geographic and temporal variability in FIB subtypes can result in
incorrect source classification as well as the need for constant library maintenance
and validation [55].
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B. Badgley and C. Hagedorn
Beaches across the USA are regularly monitored for FIB to protect the public from
waterborne diseases associated with fecal contamination, as required by the
Beaches Environmental Assessment and Coastal Health (BEACH) Act [45,
46]. When FIB concentrations exceed regulatory standards, swimming advisories
are issued and beaches may be closed to recreational use. Closed beaches lead to
frustration for beachgoers and substantial economic losses for associated communities. To protect public health, regulatory officials and beach managers need fast
and reliable tests for analyzing the bacteriological quality of beach waters. To meet
this need, a qPCR method for enterococci is now available as a rapid analytical
USEPA-approved tool for testing beach water quality. Test results can be obtained
in 2–4 h as compared to 18–24 h for conventional culture-based methods [23, 47,
48]. A second benefit is that deployment of a qPCR-based protocol for Enterococcus enumeration makes it relatively easy to use a qPCR-based MST marker for
human-source contamination. This second source-specific assay could be run either
in tandem or as a same-day follow-up to enterococci counts that were determined to
exceed the regulatory standard earlier in the day [6]. Similar to watersheds, a
variety of sources of fecal pollution potentially exist at recreational beaches. It is
therefore important to place the highest priority on evaluating whether human fecal
pollution contributes significantly to the FIB load, as human fecal material contains
a greater number of human pathogens and represents the greatest potential health
threat.
3 Microbial Source Tracking Methods
3.1 Library-Dependent Approach
Throughout the history of MST development, two basic strategies for host identification have been employed. Many early studies used a library-dependent approach
that involves constructing a database of FIB isolate types from known fecal sources
[19, 49]. Typing of indicator bacteria can be done in a variety of ways, including
antibiotic resistance [50, 51], carbon source utilization [52], or genetic diversity
[53, 54]. Isolates of FIB from water samples can then be similarly typed and
classified to a particular source by referencing the library. While this approach
showed some early success and is abundant in the literature, it is not currently
recommended for general application. Initial construction of the reference library is
costly, and geographic and temporal variability in FIB subtypes can result in
incorrect source classification as well as the need for constant library maintenance
and validation [55].
272
B. Badgley and C. Hagedorn