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Background

Background. Objective. Conclusions. References. Results. Materials & Methods. Acknowledgements. Prevalence of Faecal Shedding on Scottish Beef Cattle Farms of verocytotoxigenic Escherichia coli serogroups O26, O103, O111 and O145.

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Background

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  1. Background Objective Conclusions References Results Materials & Methods Acknowledgements Prevalence of Faecal Shedding on Scottish Beef Cattle Farms of verocytotoxigenic Escherichia coli serogroups O26, O103, O111 and O145 J.C. Low1, I.J. McKendrick2, D.J. Mellor3, G.J. Gunn1, M. Hall1, J. Evans1, H.I. Knight1,4, Stuart. W. Naylor1, M.E.J. Woolhouse4. 1Animal Health Group, SAC, West Mains Road, Edinburgh, EH9 3JG, United Kingdom. 2Biomathematics and Statistics Scotland, Edinburgh, EH9 3JZ, United Kingdom.. 3Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, 464 Bearsden Road, Glasgow, G61 1QH, United Kingdom. 4Centre for Infectious Diseases, Chancellor's Building, University of Edinburgh, 49 Little France Cresent, Edinburgh, EH16 4SB, United Kingdom. Immunomagnetic separation (IMS) beads are used for the capture of major serogroups (O26, O103, O111 and O145) - (Captivate - LabM) & for O157 (Dynal). Detection limits are in the order of 102 CFU/g of faeces. Verocytotoxin (VT) producing Escherichia coli (VTEC), especially strains of serotype O157:H7, are significant food poisoning pathogens that can cause a severe and potentially fatal illness in humans (Ammon, 1997). Possible outcomes of infection are haemorrhagic colitis (HC), and haemolytic uraemic syndrome (HUS). All VTEC strains produce verocytotoxins (either VT1 or VT2 or both). VTEC strains causing human infections belong to a large number of serotypes. Most outbreaks and sporadic cases of HC and HUS in the UK are attributed to serotype O157:H7 (Smith et al. 2001). However, there is no routine testing of human cases in UK for non-O157 strains and their significance for human health is largely unknown (Smith et al. 2001). Serogroup O26 is considered the second most common cause of HUS in UK (Smith et al. 2001) and E. coli serogroups O26 and O111 have been important causes of human VTEC infection in Australia. Serogroups O26, O103, O111, O145 are regarded as especially likely to cause severe human infections (Boerlin, et al. 1999; Schmidt, et al. 2001). Internationally, Scotland has a high rate of E. coli O157 related human disease. Domestic ruminants, especially cattle and sheep, are major reservoirs of VTEC. However, for non-O157 VTEC, no cattle shedding prevalence data is available in UK and there is little quantifiable data. Thus non-O157 serotypes may emerge as more frequent human pathogens from this animal reservoir. E. coli O26 and O103 were the most frequently isolated non-O157 serogroups. O111 strains were not detected. Prevalence in cattle of non-O157 VTEC is lower than for VT positive E. coli O157. Molecular characterisation identified VT positive strains predominately from the O26 serogroup isolates. VTEC positive serogroup O26 strains were common and positive farms were widely dispersed across Scotland. To establish the prevalence of the most important non-O157 serogroups of VTEC in Scottish cattle closest to slaughter. Ammon, A. (1997). Eurosurveillance. 2. 91-96. Boerlin, P., et. al. (1999). J. Clin. Micro. 37: 497-503. Schmidt, H., et. al. (2001). Conference Proceedings on ‘Epidemiology of Verocytotoxigenic E. coli’. ISBN 1 84170 147 5. p. 124-129. Smith, H. R., et. al. (2001). Conference Proceedings on ‘Epidemiology of Verocytotoxigenic E. coli’. ISBN 1 84170 147 5. p. 28-34. Faecal samples collected by the IPRAVE study from randomly selected cattle farms throughout Scotland. The study designed to detect non-O157 VTEC with 90% likelihood of identifying a farm as truly positive if 8% of finishing/store cattle are shedding, and with 80% likelihood if 2% of finishing/store cattle are shedding. Each sample is tested by immunomagnetic separation (IMS) for five serogroups. IMS increases the detection of VTEC O26 and O157 in cattle faeces substantially over that achieved by VT gene detection through DNA hybridisation (unpublished data). IMS is appropriate for large-scale prevalence studies of non-O157 VTEC with subsequent molecular characterisation of isolates. The work was funded by Food Standards Agency Scotland and supported by the International Partnership Research Award in Veterinary Epidemiology (IPRAVE), “Epidemiology and Evolution of Enterobacteriaceae Infections in Humans and Domestic Animals” that was funded by Wellcome Trust. The Scottish Executive Environment and Rural Affairs Department (SEERAD) provide financial support to SAC. Thanks are due to Tom Cheasty (HPA Colindale) and Simon Illingworth (LabM) for advice and assistance.

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