B11010: Review of past and current research on verocytotoxin producing Escherichia coli (VTEC) in relation to public health protection.

Study Duration: 1 August 2004 to 1 June 2008

Contractor: Campden and Chorleywood Food Research Association

E. coli is a common bacterium found in the intestines of many animals including man. One group of pathogenic E. coli is VTEC, which comprises a large group of E. coli serotypes capable of producing Verocytotoxins (VT). The most notable VTEC serotype is O157:H7, which was first recognised as a foodborne pathogen in 1982.

Given the clinical importance of VTEC this review has a deliberately wide scope and brings together scientific evidence and expert opinion from around the world. It covers every aspect of VTEC research from studies with these bacteria, the characteristics, including known virulence associated genes, methodology, clinical aspects of VTEC infection, epidemiology in humans, reservoirs for VTEC in the food chain and prevention and control of contamination.

This review represents a ‘stock-take’ of past and current research on VTEC, with particular emphasis on what is currently known about these organisms and the relevance of this information to public health, safety and protection. What makes this review so valuable is the cooperation and the expert opinion of 66 VTEC researchers from 19 countries. As well as including gaps in knowledge identified in published literature and the public domain, this review includes the personal opinions of researchers, based on their knowledge and their own experience of working with VTEC. It has deliberately focussed on research published during the last 7 years (2000 to 2007), and whilst it has been impossible to include information from every published study, important scientific discoveries relating to VTEC and key publications from the last 20 years have been included.

This review is intended to assist the Food Standards Agency with future policy decisions on VTEC research and risk management, enabling the Agency to provide effective guidance and advice applicable to different sectors of the food chain and consumers. It is also likely to benefit other Government agencies and enforcement bodies as well as other organisations with an interest in VTEC and food safety research.
The scope of this farm-to-fork review is wide and topics covered include our understanding about the ecology of VTEC, virulence characteristics and pathogenesis, methodology, clinical aspects of VTEC infection, epidemiology, and past, current and future control and intervention strategies.

Some important gaps in our knowledge include:

• Alternative mechanisms of attachment/colonisation used by some VTEC
• Additional virulence associated genes and their role in pathogenesis
• Non-O157 VTEC habitats, ecology, clinical significance and methods for detection and isolation
• The geographical distribution of VTEC serotypes
• Associations between seropathotype and human disease

This review concludes that, given the widespread distribution of VTEC, future priorities will be to focus on preventing contamination and the implementation of appropriate intervention strategies and controls in the environment and throughout the food chain.

Avoiding contamination in the first place should be the primary objective, including preventing colonisation of cattle, consistent application of good agriculture practices and ensuring that animals entering the slaughterhouse are clean. The adoption of HACCP principles by industry will contribute to safer food and reduce the risk from VTEC and proper cooking and good handling practices in both commercial and domestic settings will also be important in preventing VTEC infection.

This review has achieved two important goals. It brings together a wealth of information on VTEC research and related topics and provides information on gaps in knowledge identified in each of the different areas of VTEC research covered within this review. The up-to-date information provided will assist with the development of appropriate intervention strategies at all stages in the food chain and the implementation of better preventative measures and controls necessary to ensure public health protection in the future.