Phenotypic and Genotypic Characteristics of Shiga Toxin-Producing Escherichia coli Isolated from Surface Waters and Sediments in a Canadian Urban-Agricultural Landscape.
A hydrophobic grid membrane filtration-Shiga toxin immunoblot method was used to examine the prevalence of Shiga toxin-producing Escherichia coli (STEC) in four watersheds located in the Lower Mainland of British Columbia, Canada, a region characterized by rapid urbanization and intensive agricultural activity. STEC were recovered from 21.6, 23.2, 19.5, and 9.2% of surface water samples collected monthly from five sites in each watershed over a period of 1 year. Overall prevalence was subject to seasonal variation however, ranging between 13.3% during fall months and 34.3% during winter months. STEC were also recovered from 23.8% of sediment samples collected in one randomly selected site. One hundred distinct STEC isolates distributed among 29 definitive and 4 ambiguous or indeterminate serotypes were recovered from water and sediments, including isolates from Canadian "priority" serogroups O157 (3), O26 (4), O103 (5), and O111 (7). Forty seven isolates were further characterized by analysis of whole genome sequences to detect Shiga toxin gene (stx 1 and stx 2), intimin gene (eaeA) allelic variants and acquired virulence factors. These analyses collectively showed that surface waters from the region support highly diverse STEC populations that include strains with virulence factors commonly associated with human pathotypes. The present work served to characterize the microbiological hazard implied by STEC to support future assessments of risks to public health arising from non-agricultural and agricultural uses of surface water resources in the region.
Food, Nutrition and Health, Faculty of Land and Food Systems, University of British Columbia Vancouver, BC, Canada.
Stephanie
S
Nadya
Agriculture and Agri-Food Canada, Summerland Research and Development Centre Summerland, BC, Canada.
Pascal
P
Delaquis
Food, Nutrition and Health, Faculty of Land and Food Systems, University of British Columbia Vancouver, BC, Canada.
Jessica
J
Chen
Food, Nutrition and Health, Faculty of Land and Food Systems, University of British Columbia Vancouver, BC, Canada.
Kevin
K
Allen
Public Health Agency of Canada, National Microbiology Laboratory at Guelph Guelph, ON, Canada.
Roger P
RP
Johnson
Public Health Agency of Canada, National Microbiology Laboratory at Guelph Guelph, ON, Canada.
Kim
K
Ziebell
Laboratory for Foodborne Zoonoses, Public Health Agency of Canada Lethbridge, AB, Canada.
Chad
C
Laing
Laboratory for Foodborne Zoonoses, Public Health Agency of Canada Lethbridge, AB, Canada.
Victor
V
Gannon
Agriculture and Agri-Food Canada, Summerland Research and Development Centre Summerland, BC, Canada.
Susan
S
Bach
Agriculture and Agri-Food Canada, London Research and Development Centre London, ON, Canada.
Edward
E
Topp
D018829:Adhesins, Bacterial / Q000235:genetics*; D000383:Agriculture; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D001955:British Columbia; D004269:DNA, Bacterial / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics*; D016680:Genome, Bacterial / Q000235:genetics; D019015:Geologic Sediments / Q000382:microbiology*; D006801:Humans; D016133:Polymerase Chain Reaction; D012621:Seasons; D017422:Sequence Analysis, DNA; D022622:Shiga Toxin 1 / Q000235:genetics*; D022641:Shiga Toxin 2 / Q000235:genetics*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D014871:Water Microbiology
D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; C073819:eaeA protein, E coli
Shiga toxin-producing E. coli (STEC); prevalence; sediment; surface water; whole-genome sequencing