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The objective of this work was to evaluate culture-based and quantitative polymerasechain reaction (PCR)-based methods for the detection of Yersinia spp. in water, by examining itsoccurrence in the Grand River watershed in Southwestern Ontario, Canada. This watershed isused as a drinking water source for up to 500,000 people, as well as for recreational purposes. Itis also one of the most heavily impacted watersheds in Canada and receives inputs from bothagricultural and urban activities. Five sampling locations were selected along the Grand River inthe area surrounding the cities of Kitchener and Waterloo. Surface water was collected from eachof these sites every other week. In this study, culture-based work involved comparing four different enrichment broths aswell as examining the effect of an alkaline treatment of cultures grown in each enrichment broth.The methods were selected from the literature and were originally developed for and arecommonly used for isolating Y. enterocolitica from food and clinical samples. These methodshave not been tested extensively on water. Results showed that one of the enrichment brothstested, modified tryptic soy broth (mTSB), appeared to have more potential for recovery of Y.enterocolitica than the others. Additionally, an alkaline treatment was found to be effective.Consequently, the mTSB enrichment broth with and without an alkaline treatment followed bygrowth on Cefsulodin-Irgasan-Novobiocin (CIN) agar, a commonly used selective agar for Y.enterocolitica, was used to isolate Yersinia from surface water samples from the Grand River.Presumptive Yersinia isolates were confirmed with a series of biochemical tests. ConfirmedYersinia strains were isolated from 39 out of 154 (25%) surface water samples collected betweenApril 2006 and May 2007. Isolated strains were then sub-typed to determine their species andbiotype. None of the strains isolated were Y. enterocolitica. Species that were isolated includedY. aldovae, Y. bercovieri, Y. frederiksenii and Y. intermedia, all typically considered to be nonpathogenicspecies. Non-pathogenic Yersinia species have previously been found in aquaticenvironments. Strains isolated in 2006 were also screened for the two virulence genestargeted in the molecular-based methods and the surface water isolates did notcontain either gene. Includes 9 references.

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Edition: Vol. - No. Published: 11/01/2007 Number of Pages: 4File Size: 1 file , 130 KB