Citation:

Haugland, R A., S D. Siefring, L J. Wymer, K Brenner, AND A P. Dufour. COMPARISON OF ENTEROCOCCUS MEASUREMENTS IN FRESHWATER AT TWO RECREATIONAL BEACHES BY QUANTITATIVE POLYMERASE CHAIN REACTION AND MEMBRANE FILER CULTURE ANALYSIS. WATER RESEARCH 39(4):559-568, (2005).

Impact/Purpose:

The objectives of this research are: (1) to evaluate rapid state-of-the-art measuement methods of pathogens that may indicate the presence of fecal pollution in recreational waters (beaches); (2) to obtain, jointly with a sister laboratory (NHEERL), a new set of water quality data and related health effects data at a variety of beaches across the U.S., in both marine and non-marine waters; (3) to analyze the research data set to evaluate the utility of the tested measurement methods, the new EMPACT monitoring protocol, and the health effects data / questionnaire, in order to establish a relationship between measured pathogens and observed health effects; and (4) to communicate the results to the Office of Water in support of their efforts to develop new state and/or federal guidelines and limits for water quality indicators of fecal contamination, so that beach managers and public health officials can alert the public about the potential health hazards before exposure to unsafe water can occur.

Description:

Cell densities of the fecal pollution indicator genus, Enterococcus, were determined by a rapid (2-3 hr) quantitative PCR (QPCR) analysis based method in 100 ml water samples collected from recreational beaches on Lake Michigan and Lake Erie during the summer of 2003. Enumeration results by this method were compared with counts of Enterococcus.colony forming units (CFU) determined by filter plating on mEI-agar selective medium. The QPCR method showed a 95% confidence, minimum detection limit of approximately two Enterococcus cells per sample in analyses of undiluted DNA extracts and highly accurate quantitation of spiked lake water samples based on the geometric means of replicate sample results. Geometric means of Enterococcus densities, determined from multiple collection points during each sampling visit, showed approximately lognormal distributions at both beaches using both QPCR and culture analyses. These geometric means ranged from 10 to 8548 cells by QPCR analysis and 1 to 2499 CFU by culture analysis in Lake Michigan (N = 56) and from 8 to 8695 cells by QPCR analysis and 3 to 1941 CFU by culture analysis in Lake Erie (N = 47). Regression analysis of these results showed a high level of agreement between the two methods with an overall correlation coefficient of 0.68.

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