Occurrence and persistence of Escherichia coli O157:H7 in water

Nwachuku, Nena; Gerba, Charles P.

doi:10.1007/s11157-008-9132-0

Cited by 20 publications

(18 citation statements)

References 56 publications

(54 reference statements)

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“…These pathotypes include Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), and enteroaggregative E. coli, and they are implicated in many waterborne outbreaks, including those in Canada (9)(10)(11). Among these pathotypes, STEC and EPEC are responsible for frequent waterborne outbreaks worldwide (9,10,12,13). In British Columbia (BC), Canada, the rate of STEC infections has remained above the Canadian average since 2004, ranging between 2.4 and 4.3 cases/ 100,000 individuals (14).…”

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confidence: 99%

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

Chandran

Mazumder

2015

Appl Environ Microbiol

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Escherichia coli isolates (n ‫؍‬ 658) obtained from drinking water intakes of Comox Lake (2011 to 2013) were screened for the following virulence genes (VGs): stx 1 and stx 2 (Shiga toxin-producing E. coli [STEC]), eae and the adherence factor (EAF) gene (enteropathogenic E. coli [EPEC]), heat-stable (ST) enterotoxin (variants STh and STp) and heat-labile enterotoxin (LT) genes (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). The only genes detected were eae and stx 2 , which were carried by 37.69% (n ‫؍‬ 248) of the isolates. Only eae was harbored by 26.74% (n ‫؍‬ 176) of the isolates, representing potential atypical EPEC strains, while only stx 2 was detected in 10.33% (n ‫؍‬ 68) of the isolates, indicating potential STEC strains. Moreover, four isolates were positive for both the stx 2 and eae genes, representing potential EHEC strains. The prevalence of VGs (eae or stx 2 ) was significantly (P < 0.0001) higher in the fall season, and multiple genes (eae plus stx 2 ) were detected only in fall. Repetitive element palindromic PCR (rep-PCR) fingerprint analysis of 658 E. coli isolates identified 335 unique fingerprints, with an overall Shannon diversity (H=) index of 3.653. Diversity varied among seasons over the years, with relatively higher diversity during fall. Multivariate analysis of variance (MANOVA) revealed that the majority of the fingerprints showed a tendency to cluster according to year, season, and month. Taken together, the results indicated that the diversity and population structure of E. coli fluctuate on a temporal scale, reflecting the presence of diverse host sources and their behavior over time in the watershed. Furthermore, the occurrence of potentially pathogenic E. coli strains in the drinking water intakes highlights the risk to human health associated with direct and indirect consumption of untreated surface water. F ecal contamination is the primary contributor of pathogens to surface water and constitutes a significant public health risk. In Canada, the estimated rate of acute gastrointestinal illness attributable to water is 0.11 cases per person per year, which poses a substantial economic burden (1). Traditionally, the safety of water used for drinking and recreation as required by regulation is assessed in terms of the concentration of Escherichia coli, a dominant intestinal inhabitant of humans and warm-blooded animals, whose presence in water indicates fecal contamination and the potential presence of enteric pathogens (2). The sources of E. coli in the aquatic environment can originate from runoff from land applied with animal wastes or animal feeding operations, urban runoff, inadequate or failing septic or sewer systems, and wildlife (3). Identification of the source of fecal pollution is a high priority in order to protect and manage source water quality and also to assess the potential public health risk associated with fecal contamination from a given host source (4). To this end, many advances have been made in recent years to develop various ...

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confidence: 99%

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

Chandran

Mazumder

2015

Appl Environ Microbiol

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“…These can also be transported to the surface water through surface runoff containing bird droppings. The occurrence of STEC and EPEC has been detected in surface waters (28,29), and subsequent outbreaks from such contaminated waters have also been reported (3,4,11). Birds are often implicated as vectors in outbreaks of human infections (45) and are considered a threat to human health (42).…”

Section: Discussionmentioning

confidence: 99%

“…Among the diarrheagenic pathotypes of E. coli, STEC and EPEC are more frequently associated with waterborne outbreaks worldwide (2,3,10,11). The ability of STEC to cause disease is associated with the production of Shiga-like toxins, Stx1 and Stx2 (encoded by the stx 1 and stx 2 genes) and related virulence factors.…”

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confidence: 99%

Occurrence of Diarrheagenic Virulence Genes and Genetic Diversity in Escherichia coli Isolates from Fecal Material of Various Avian Hosts in British Columbia, Canada

Chandran

Mazumder

2014

Appl Environ Microbiol

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Contamination of surface water by fecal microorganisms originating from human and nonhuman sources is a public health concern. In the present study, Escherichia coli isolates (n ‫؍‬ 412) from the feces of various avian host sources were screened for various virulence genes: stx 1 and stx 2 (Shiga toxin-producing E. ). None of the isolates were found to be positive for stx 1 , while 23% (n ‫؍‬ 93) were positive for only stx 2 , representing STEC, and 15% (n ‫؍‬ 63) were positive for only eae, representing EPEC. In addition, five strains obtained from pheasant were positive for both stx 2 and eae and were confirmed as non-O157 by using an E. coli O157 rfb (rfb O157 ) TaqMan assay. Isolates positive for the virulence genes associated with ETEC and EIEC were not detected in any of the hosts. The repetitive element palindromic PCR (rep-PCR) fingerprint analysis identified 143 unique fingerprints, with an overall Shannon diversity index of 2.36. Multivariate analysis of variance (MANOVA) showed that the majority of the STEC and EPEC isolates were genotypically distinct from nonpathogenic E. coli and clustered independently. MANOVA analysis also revealed spatial variation among the E. coli isolates, since the majority of the isolates clustered according to the sampling locations. Although the presence of virulence genes alone cannot be used to determine the pathogenicity of strains, results from this study show that potentially pathogenic STEC and EPEC strains can be found in some of the avian hosts studied and may contaminate surface water and potentially impact human health.

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“…Shiga-toxin producing E. coli O157:H7 has been well documented to survive extended periods in water and has been linked to outbreaks associated with drinking and bathing waters (Williams et al 2007;Avery et al 2008;Nwachuku and Gerba 2008). This study demonstrated the survival of E. coli O157:H7 EDL 933 in groundwater for 70 days.…”

Section: Discussionmentioning

confidence: 67%

Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

Marucci

Cubitto

2016

Environ Monit Assess

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The experiments were performed with Escherichia coli O157:H7 EDL 933 in freshwater microcosms at 12 °C. At 35, 45, and 70 days, samples were taken and filtered through 0.45 μm membrane filters. The following alternatives were tested to evaluate the recovery percentage of injured cells: (1) selective media CHROMagar(™)O157 and chromID(™)O157:H7 agar, at 37 °C for 24 h; (2) tryptic soy agar supplemented with yeast extract (TSAE), incubated at 25 °C for 2 or 4 h, then transferred to CHROMagar(™)O157 or chromID(™)O157:H7 agar at 37 °C (TSAE2h-CHROM, TSAE4h-CHROM and TSAE2h-ID, TSAE4h-ID); (3) thin agar layer (TAL) method, TSAE was overlaid on CHROMagar(™)O157 or chromID(™)O157:H7 agar (TALCHROM and TALID, respectively) and incubated at 37 °C for 24 h; and (4) TALCHROM at 25 °C for 4 h, then continued up to complete 24 h at 37 °C (TALCHROM4h). Furthermore, the recovery of E. coli O157:H7 cells adhering to glass coverslips were evaluated to mimic biofilm conditions. The recovery percentages obtained from each alternative were calculated relative to TSAE counts. After 70 days, TSAE4h-CHROM and TALCHROM4h showed the highest recovery percentage (>90 %) from water microcosms. Despite the improved recovery of cell adhering to glass surfaces, the percentages obtained with TSAE4h-CHROM were low. Further studies for the recovery of biofilm-forming E. coli O157:H7 are required. Pre-incubation on TSAE at 25 °C for 4 h, combined with CHROMagar(™)O157, or by thin agar layer method (TALCHROM) enhanced significantly the recovery of viable cells of E. coli O157:H7 after prolonged stay in water microcosms.

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Occurrence and persistence of Escherichia coli O157:H7 in water

Abstract: Escherichia coli O157:H7 has been associated with water related outbreaks. It has been isolated from surface and ground waters. It is capable of survival in water for days to weeks

Cited by 20 publications

References 56 publications

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

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

Occurrence of Diarrheagenic Virulence Genes and Genetic Diversity in Escherichia coli Isolates from Fecal Material of Various Avian Hosts in British Columbia, Canada

Strategies for recovering of planktonic and sessile cells of Escherichia coli O157:H7 from freshwater environment

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