%0 Journal Article
%T Verotoxigenic Escherichia coli O157:H7 from Swedish cattle; isolates from prevalence studies versus strains linked to human infections - A retrospective study
%A Anna Asp¨˘n
%A Erik Eriksson
%J BMC Veterinary Research
%D 2010
%I BioMed Central
%R 10.1186/1746-6148-6-7
%X Characterization by phage typing and molecular methods of the strains isolated from these 18 farms, including PCR for virulence genes (vtx1, vtx2 and variants thereof, eaeA and EHEC-hlyA) and Pulsed-Field Gel Electrophoresis (PFGE), demonstrated a cluster of very similar strains from 16 farms. All were of phage type 4, carried the genes encoding the verotoxins VT2 and VT2c, intimin, EHEC-haemolysin and flagellin H7 as shown by PCR, and had identical or very similar PFGE patterns. When analysing strains in a prevalence study of VTEC O157:H7 from cattle at slaughter as well as from an on-farm prevalence study of dairy cattle, using the same typing methods, a rather wide variation was observed among the isolated VTEC O157:H7 strains.In Sweden, a limited group of genetically similar and highly pathogenic VTEC O157:H7 strains seem to predominate in direct or indirect transmission from cattle to man.Verotoxin-producing Escherichia coli (VTEC) O157:H7 was first recognized as a human pathogen in 1982 [1]. As it was associated with consumption of undercooked 'hamburgers', it became known as 'the hamburger bug'. As it has subsequently been found that healthy cattle can harbour the bacterium, ruminants are now regarded as its main reservoir, though VTEC O157:H7 has been isolated from other animal species such as sheep, pigs, geese, gulls and pet animals [2]. Especially undercooked meat of bovine origin but also unpasteurized milk and other dairy products have been implicated in transmitting VTEC O157:H7 to humans. Another route for acquiring the infection is direct transmission from cattle, especially calves, for instance on 'open farms' where groups of children are welcome to visit. As the bacterium survives well in the environment, drinking water, vegetables irrigated with contaminated water, and public outdoor swimming pools have been mentioned as sources of community outbreaks. Direct person-to-person transmission also occurs, as the infectious dose of the bacterium is ver
%U http://www.biomedcentral.com/1746-6148/6/7