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Title: Determining the main source of human Escherichia coli O157 infection in Grampian and investigating the effects of brassicas on the shedding of this pathogen in sheep
Author: Fraser, Eilidh M.
ISNI:       0000 0004 5361 6175
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2014
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Human E. coli O157 isolates were typed by multi locus variable number tandem repeat analysis (MLVA) and household outbreaks were identified. The genetic variation found within the household cases of E. coli O157 was compared to the background variation found in sporadic isolates to determine if the isolates within each household were related to each other or if they were from multiple genotypes. The results showed that 83% of household outbreaks were closely related to each other and were acquired from the same source, whilst the remainder of cases could be a result of multiple strain carriage within the source of infection. Cattle, sheep and human isolates were compared using MLVA and population genetic methods were used to identify the degree of host association between cattle and sheep isolates. This was to determine whether cattle or sheep are the main source of human E. coli O157 infection. The results showed that no host association exists between cattle and sheep isolates. This suggests that cattle and sheep isolates are part of the same population and can circulate between each host. Further, flocks of sheep in Grampian were tested for E. coli O157 whilst they were grazing on pasture in winter, brassicas in spring and on pasture during the summer, to see if a diet of brassicas had an effect on the faecal shedding of E. coli O157 in sheep. Statistical analysis showed significant differences between the shedding of E. coli O157 in sheep grazing on brassicas in spring when compared to sheep grazing on pasture in the summer (P< 0.01) and in winter (P<0.05), suggesting that a diet of brassicas may have an effect on the shedding of E. coli O157 in sheep.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available