ARS | Publication request: Assessment of three remediation strategies for reduction of Shiga-toxigenic Escherichia coli (STEC) O157 in naturally contaminated soil

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2007
Publication Date: July 28, 2007
Citation: Durso, L.M., Keen, J.E., Bauer, N., Mcbride, M.T., Dunn, J.R. 2007. Assessment of three remediation strategies for reduction of Shiga-toxigenic Escherichia coli (STEC) O157 in naturally contaminated soil [abstract]. Annual Meeting Institute of Food Technologists. Abstract No. 098-27.

Technical Abstract: Justification: Cattle are a known reservoir of the foodborne pathogen STEC O157. After being shed from the animal, the contaminated feces become incorporated in the soil. Objective: To evaluate three potential strategies for remediation of STEC O157 from naturally contaminated soils. Methods: The study plots were part of a human outbreak that had been epidemiologically linked to petting zoo animals. They had remained STEC-O157 positive for over three months before treatment began. Positive plots were subdivided into 160 individual 1-foot square sample treatment areas and randomly assigned to one of three treatments (flame, disinfectant, or lime), or control. Surface soil cores were collected from each plot and tested on days 0, 7, and 14 for STEC O157. Results: Neither disinfectant nor flame treatments tried were effective at reducing STEC O157 in the soil, compared to the control. The disinfectant used, a peroxygen compound called Virkon, has a broad antimicrobial activity and was used extensively in the foot-and-mouth outbreaks in England, however, its efficacy here may have been affected by the dose used and the organic content of the soil. The flame treatment, while potentially effective for surface sterilization, was not effective for the 2-3 inch cores taken for this study. Lime plots showed an increase in STEC O157 isolation at day 7, compared to the control, potentially due to pH effects, and no effect at day 14 compared to the control. Significance to food science field: STEC O157 can be isolated from livestock-associated soils, making the soil a potential pre-harvest food safety control point. However, the three remediation strategies investigated in this study were not effective at reducing STEC O157 in the soil.