Survival of various ERIC-genotypes of Shiga toxin-producing Escherichia coli in well water

Leigh Watterworth, Bruce Rosa, Heidi Schraft, Edward Topp, Kam Tin Leung

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Recently, there has been a surge of interest in understanding the survival of Shiga toxin-producing Escherichia coli (STEC) in aquatic environments. Fifteen strains of STEC were monitored, individually, in untreated well water samples incubated at 10 and 22°C for 56 days. The strains were selected from three serogroups (O26, Ol11 and O157) and represented five distinct ERIC (enterobacterial repetitive intergenic concensus)-genotypes. The microcosms were prepared in triplicate and inoculated at an initial cell density of about 7.0 log CFU/ml well water. At 10°C, the cell density of five STEC strains fell below the detection limit of 0.8 log CFU/ml by day 56. Of the ten persisting strains, four showed superior survival with cell densities decreasing to an average of about 5 log CFU/ml while the remaining six strains showed moderate levels of survival, decreasing to an average cell density of about 3 log CFU/ml. At 22°C, strain H32 (genotype I) and H15 (genotype B) persisted at 1.1 log CFU/ml and 2.2 log CFU/ml in 56 days, respectively. The other 13 STEC strains dropped below the detection limit between weeks 3 to 8. The 15 strains demonstrated highly variable levels of survival with no correlation between ERIC-genotypes or serogroups and the strains' ability to persist in the well water samples. Although strain H32 (O157:H7) persisted significantly longer than strain H22 (O157:H7) in natural well water at both 10 and 22°C, both strains survived equally well in sterile well water, indicating that individual STEC strains vary in their ability to compete with background microbial populations.

Original languageEnglish
Pages (from-to)367-382
Number of pages16
JournalWater, Air, and Soil Pollution
Volume177
Issue number1-4
DOIs
StatePublished - Nov 2006

Keywords

  • ERIC-genotype
  • Shiga toxin-producing Escherichia coli
  • Survival
  • Well water

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