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Detection and quantification limits of the EPA Enterococcus qPCR method
Citation:
Haugland, Rich, M. Varma, AND L. Wymer. Detection and quantification limits of the EPA Enterococcus qPCR method. 12th Annual Great Lakes Beach Asssociation Conference, Mackinac Island, MI, October 16 - 18, 2012.
Impact/Purpose:
Provide technical information on the performance of the EPA Enterococcus qPCR method for monitoring recreational beach water quality to potential decision makers, stake-holders and end-users
Description:
The U.S. EPA will be recommending a quantitative polymerase chain reaction (qPCR) method targeting Enterococcus spp. as an option for monitoring recreational beach water quality in 2013 and has published preliminary proposed water quality criteria guidelines for the method. An important consideration in the implementation of this qPCR method is the relationship between its analytical sensitivity and the water quality criteria guidelines. Several previous studies have provided either indirect or rough estimations of the limit of detection (LOD) and/or limit of quantification (LOQ) of this method based on calibrator cell equivalents (CCE). Here we describe results from a more extensive study that was designed to estimate the values of these parameters. In addition, recent studies have indicated that CCE estimates can vary based on the mean ratios of target sequences recovered per cell from different cell preparations of the Enterococcus faecalis strain used for calibration. Adjustments of the LOD and LOQ estimates obtained from this study to CCE values that would be consistent with EPA qPCR water quality criteria guidelines are also presented.