Explaining the urban and rural differences of Escherichia coli 0157 human infection in Grampian

• Main Author: Solecki, Olivia
• Published: University of Aberdeen 2008
• Subjects: 616.9; Escherichia coli infections : Escherichia coli
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499729

The rural population of Grampian was reported to be two times more likely to suffer from <i>E. coli</i> O157 infection than the urban population. <i>E. coli</i> O157 was isolated from minced beef and lamb sampled in butcher shops and supermarkets in rural and urban areas, environmental samples (sheep and cattle faeces on farms) and tap water from private water supplies in the countryside using enrichment of sample, followed by immunomagnetic separation and culture on CT-SMAC agar. Clinical <i>E. coli</i> O157 isolates were recovered from patients in parallel. All <i>E. coli</i> O157 were genotyped by multilocus variable number of tandem repeats analysis (MLVA). Results from the meat survey (Nov04-Aug06) revealed a very low incidence of <i>E. coli </i>O157 in minced meat i.e. 0.75 % (4/530). The winter <i>E. coli</i> O157 sheep study (Jan-Mar05) revealed a group prevalence of 42.8 % and an individual animal prevalence of 5.8 %, consistent with a previous summer study (40 % and 6.5 % respectively) and the cattle farm prevalence was 22 % (Oct06-Jun07), consistent with previous prevalence studies in Scotland. According to MLVA data analysis, it appears that the rural community becomes ill through ingestion of <i>E. coli</i> O157 originating mostly from cattle, from which, a small proportion are infected by drinking water contaminated by cattle. Four human cases of infection living in urban areas shared the same MLVA types as rural human cases emphasising the fact that both populations can become ill from the same source i.e. city dwellers visiting the countryside or by a food widely distributed. The rest of the urban cases MLVA types were significantly different from cattle and sheep types and another source of infection was proposed i.e. travel outwith Grampian or ingestion of food produced in other countries.