Control Verocytotoxigenic E. coli.

Verocytotoxigenic Escherichia coli (VTEC) are a group of pathogenic E. coli bacteria that are causing major food safety concerns across Europe. VTEC, in particular E. coli O157:H7, has a low infectious dose and can cause severe illness, including abdominal pain and bloody diarrhea. Chronic complications, including renal failure, occur in a small number of cases, about 10%, and the illness can be fatal.

Researchers across the European Union have recognized the danger to public health posed by VTEC and the need to devise control strategies. Consequently, it is important to inform farmers, veterinarians, food producers and health authorities of the concerns so that each can act to reduce the hazard.

Investigators tackled the issue on a number of fronts. Their main focus included: developing techniques for detecting and typing of VTEC; investigating the epidemiology of VTEC infections in Europe; examining the factors affecting pathogenicity; identifying the factors affecting survival, growth and resistance of VTEC in the environment and during food production; and developing strategies for controlling the pathogen and implementing various HACCP programs.

This effort has led to the publication of booklets dealing with methods, survival and growth, pathogenicity and virulence, control and epidemiology of VTEC, available at http://www.research.teagasc.ie/vteceurope.

E. coli serotype O157:H7 was the first VTEC serotype associated with severe illness. While it is still the primary serotype associated with infection in many countries, it is clear that other serotypes are also capable of causing severe illness. Serogroups O26, O111, O103 and O145 are among the most frequently encountered non-O157 serogroups in some European countries. Serogroup O121 has been found in Sweden and Denmark. Scientists have isolated O117 in Denmark, although this serogroup has been associated with infections acquired in Asia and in Africa.

A subset of VTEC strains is known as enterohaemorrhagic E. coli (EHEC). EHEC possesses the genes for intimin and for enterohaemolysin, in addition to the genes for verocytotoxin production. A number of studies have focused on serotype O157 strain characterization. The study of the sources and transmission routes for VTEC infection allows research and resources to be focused most effectively in addressing safety issues caused by this particular pathogen. The reputation of O157:H7 as "the hamburger bug" has been called into question, as many other foodstuffs have now been identified as vehicles of infection. Vegetables and tuna fish may be vehicles of infection, with some of the largest outbreaks in Japan arising from consumption of these foods. Fruit, vegetables and water may be additional sources of infection.

Further information. Geraldine Duffy, Teagasc, The National Food Centre, Dunsinea, Castleknock, Dublin 15, Ireland; phone: [phone]; fax: [phone]; email: [e-mail].