Verocytotoxin-producing Escherichia coli (VTEC) other than serogroup O157 from Scottish cattle

摘要

Verocytotoxin (VT)-producing Escherichia coli (VTEC) causes a wide spectrum of disease in man, from mild diarrhoea to severe diseases, such as haemorrhagic colitis and haemolytic uraemic syndrome (HUS) (Karmali 1989). The capacity of strains of VTECto cause disease in human beings is associated with VT production (Melton-Celsa and O'Brien 1998), enterohaemolysin production (Schmidt and others 1995) and possession of the locus of enterocyte effacement (LEE) (Frankel and others 1998). The LEE contains the eae gene encoding intimin, a bacterial outer membrane protein involved in the intimate attachment of the bacteria to the gut mucosa of the host, of which there are five recognised types: #alpha#, #beta#, #gamma#, #delta# and #epsilon# (Adu Bobie and others 1998, Oswald and others 2000). Current epidemiological studies indicate that strains of VTEC belonging to serotype O157:H7 and O157 non-motile (H-) strains are most commonly associated with severe human disease in the UK (Willshaw and others 2001). However, this might reflect the fact that tests for the detection of non-O157 VTEC are not routinely available in most laboratories (Anon 2000). Indeed, infections with VTEC other than serogroup O157 are detected more frequently outside the UK (Schmidt and others 1999). Cattle are a reservoir of infection, and meat products derived from cattle carrying VTEC serogroup O157 represent a major source of infection for human beings (Chapman and others 1993). Non-O157 VTEC serogroups have been isolated from the faeces of cattle in many countries (Beutin and others 1993, Willshaw and others 1993, Kobayashi and others 2001), but studies of this type have not yet been carried out in Scotland. The aim of this study was to determine the prevalence and characteristics of non-O157 VTEC in Scottish cattle.