Genetic Relatedness of Escherichia coli Isolates in Interstitial Water from a Lake Huron (Canada) Beach

Abstract

Research was undertaken to characterize Escherichia coli isolates in interstitial water samples of a sandy beach on the southeastern shore of Lake Huron, Ontario, Canada. A survey of the beach area revealed the highest abundance of E. coli in interstitial water of the foreshore beach sand next to the swash zone. Higher concentrations of E. coli (up to 1.6 ؋ 10 6 CFU/100 ml of water) were observed in the interstitial water from the sampling holes on the beach itself compared to lake water and sediment. Repetitive extragenic palindromic PCR (REP-PCR) was used to characterize the genetic diversity of E. coli isolates from interstitial water samples on the beach. E. coli isolates from the same sampling location frequently exhibited the same REP-PCR pattern or were highly similar to each other. In contrast, E. coli isolates from different sampling locations represented populations distinct from each other. This study has identified a unique ecological niche within the foreshore area of the beach where E. coli may survive and possibly multiply outside of host organisms. The results are of interest as increasing concentrations of E. coli in recreational waters are often considered to be an indication of recent fecal pollution.

Pathogenic Potential, Genetic Diversity, and Population Structure of Escherichia coli Strains Isolated from a Forest-Dominated Watershed (Comox Lake) in British Columbia, Canada

“…However, contrary to that finding, the combined diversity observed in the present study was higher than that for E. coli genotypes obtained from various animal and avian host sources in different Canadian watersheds (21,22). Although the high genetic diversity of E. coli observed in our study was in agreement with previous results obtained for various aquatic environments (4,30,31,34), it is difficult to directly compare measures of diversity based on different molecular methods. In general, the sources of E. coli in contaminated surface water are dependent on the host source (animal) origin from which they are derived and their presence in the watershed.…”

“…Such variations have been observed among the genotypes of E. coli isolated from different animals and avian host sources in BC, Canada (21,22). Despite the large amount of data available on the genetic diversity of E. coli in the aquatic environment (4,30,31,34,35), only limited information is available on the temporal variation of the diversity and population structure of E. coli in the surface water over multiple years in Canada on annual, seasonal, and monthly scales. Therefore, the objectives of the present investigation were (i) to determine the prevalence of diarrheagenic virulence genes in E. coli isolates obtained from the drinking water intakes of Comox Lake and (ii) to determine the temporal variation (annual, seasonal, and monthly) in the genetic diversity and population structure of these isolates over multiple years by using repetitive element palindromic PCR (rep-PCR) fingerprinting.…”

Distribution and Diversity of Escherichia coli Populations in the South Nation River Drainage Basin, Eastern Ontario, Canada

“…Studies have revealed enormous diversity in E. coli populations in primary and various secondary habitats. These include feces from various mammalian and avian hosts (2,22), stored dairy and swine manure (39), home septic systems (19), fresh and marine surface water (35,43,56), beach sand (59), soils (7), and the freshwater macrophytic green alga Cladophora (8). Many aspects of this enormous diversity have importance for the assessment and management of water quality.…”

Population dynamics and genetic variability of Escherichia coli in a mixed land-use watershed

“…McLellan (2004) reported that there is less diversity in E. coli isolates obtained from river and beach water than in isolates from human and non-human sources. Kon et al (2007) showed that E. coli isolates in interstitial water from the same sampling location on a Lake Huron beach have highly similar rep-PCR (repetitive sequence-based polymerase chain reaction) patterns, whereas those from different sampling locations were distinctly different. In contrast, Walk et al (2007) reported lack of geographic differentiation among E. coli isolated from water and beach sand at different sampling sites on six other beaches of Lake Huron based on multilocus enzyme electrophoresis and multilocus sequence typing.…”