An evaluation of U.S. EPA aPCR methods at select Door County, WI beaches
File(s)
Date
2017-09-29Author
Campbell, Aaron
Advisor(s)
Kleinheinz, Greg
Metadata
Show full item recordAbstract
The United States Environmental Protection Agency (EPA) has adopted
numerous techniques for enumerating fecal indicator bacteria, each with varying
advantages and disadvantages. Traditional culture techniques require 18-24 hours of
incubation and do not provide results in a time sufficient manner to adequately protect
public health. To help solve this issue, the EPA has developed rapid bacterial indicator
methods based on real-time quantitative polymerase chain reaction (qPCR) technology.
Some results from these rapid methods (calibrator cell equivalents, CCE) have shown to
correlate with results from culture based methods (most probable number, MPN),
accurately predicting risk for gastro-intestinal illness. However, there are no comparative
studies that have been done in the Great Lakes or at beaches that are not directly
impacted by human fecal contributions. In this study, Enterococcus qPCR Method 1609
and E. coli qPCR Method C were compared to the defined substrate methods Enterolert
and Colilert, respectively, at four beaches in Door County, Wisconsin. Baileys Harbor
beach does not exhibit any significant correlations (p>0.05) between the qPCR methods
and defined substrate methods (r2=0.025 (Enterococcus) and 0.002 (E. coli)). Fish Creek
beach shows a positive correlation between Enterococcus qPCR and culture methods (r2=
0.387. p<0.01), while method C does not show any significant correlation (r2=0.01,
p>0.05). Otumba beach shows weakly positive correlations for both qPCR assays and
their associated cultures (Enterococcus r2= 0.141 (p=0.0169), E. coli r2=0.363 (p<0.01).
Correlations for Sunset beach have r2 values of 0.021 for Enterococcus (p>0.05) and
0.104 for E. coli (p=0.0307).
In addition to the correlations, the agreement between methods was recorded and
compared to current regulatory standards. If adopted as the regulatory method, qPCR
methods would result in a minimum increase of beach closures of 10 percent and a
maximum increase of 47 percent for either method. This suggests that qPCR would be
more protective of public health than current culture based enumeration methods. These
increases in beach closures may have potential social and economic ramifications in local
communities. While it is clear much research is needed to distinguish which method is
more appropriate for the Great Lakes Region and this study suggests a site by site
evaluation of qPCR testing methods before they are adopted for use in monitoring
recreational water quality.
Subject
Water quality
Beach closures--Wisconsin--Door County, Wisconsin
Enterococcal infections
Lakes--Recreational use
Enterococcus--Environmental aspects--Door County, Wisconsin.
Permanent Link
http://digital.library.wisc.edu/1793/76930Description
A Thesis Submitted In Partial Fulfillment of the Requirements For the Degree of Master of Science-Biology in Microbiology