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Title: Movement and survival of Escherichia coli O157 in the environment
Author: Gordon, Helen E.
ISNI:       0000 0001 3506 0351
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2008
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E. coli O157 is shed into the environment from the faeces of infected animals. Once in the soil, the availability of hydrological pathways enables cells to disperse through the soil and enter the groundwater.  This thesis investigates the transmission and survival of E. coli O157 in the farming environment with particular emphasis on the role of hydrological pathways.  Findings from fieldwork included the observation that E. coli O157 population densities in faeces varied due to animal shedding rates and increasing temperature.  Rainfall events were found to increase transport of E. coli O157 to a local stream.  Strain typing using MLVA demonstrated that one strain had been transported from faeces into overland flow. Microcosm based experiments found that soil water content, temperature and soil type affected the recoverability of E. coli O157 from soil.  The transport of E. coli O157 was influenced by the presence of preferential flow pathways under heavy rainfall conditions.  The days after rainfall event caused changes in both the population density and the cellular activity of E. coli O157. The population dynamics and activity of E. coli O157 was monitored in different environmental matrices at different temperatures.  These variables were found to influence the population and cellular activity of E. coli O157.  During this experiment, cells appeared to enter a viable but non-culturable state. The study showed that the dispersal of E. coli O157 is mediated by soil-related hydrological pathways.  By using the thesis findings to improve current risk assessment strategies, the number of E. coli O157 cases from environmental sources may be reduced.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available