Quantitative PCR measurements of Escherichia coli including Shiga Toxin-Producing E. coli (STEC) in Animal Feces and Environmental Waters
2015
Ahmed, W. | Gyawali, P. | Toze, S.
Quantitative PCR (qPCR) assays were used to determine the concentrations of E. coli including shiga toxin-producing E. coli (STEC) associated virulence genes (eaeA, stx₁, stx₂, and hlyA) in ten animal species (fecal sources) and environmental water samples in Southeast Queensland, Australia. The mean Log₁₀ concentrations and standard deviations of E. coli 23S rRNA across fecal sources ranged from 1.3 ± 0.1 (horse) to 6.3 ± 0.4 (cattle wastewater) gene copies at a test concentration of 10 ng of DNA. The differences in mean concentrations of E. coli 23S rRNA gene copies among fecal source samples were significantly different from each other (P < 0.0001). Among the virulence genes, stx₂ (25%, 95% CI, 17–33%) was most prevalent among fecal sources, followed by eaeA (19%, 95% CI, 12–27%), stx₁ (11%, 95% CI, 5%–17%) and hlyA (8%, 95% CI, 3–13%). The Log₁₀ concentrations of STEC virulence genes in cattle wastewater samples ranged from 3.8 to 5.0 gene copies at a test concentration of 10 ng of DNA. Of the 18 environmental water samples tested, three (17%) were positive for eaeA and two (11%) samples were also positive for the stx₂ virulence genes. The data presented in this study will aid in the estimation of quantitative microbial risk assessment (QMRA) from fecal pollution of domestic and wild animals in drinking/recreational water catchments.
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