It is a fact that the diversity of food-borne pathogens is increasing in Europe, as well as globally. One explanation for this increase is environmental stress factors, such as food preservation methods, that leads to changes in genotypes and consequently enhanced survival, resistance, or virulence in the pathogens.
To tackle the problem, an on-going European funded 'Quality of Life' project is currently investigating a simple method for purifying DNA from bacterial cultures in order to establish a central databank of DNA sample materials and key food-pathogen DNA sequences.
The project was motivated by the clear need for improved methods to detect and identify the pathogens complex. For example, a recent US survey revealed that only 18 per cent of 76 million illnesses every year in USA are caused by known pathogens.
A recent statement from the PCR project highlights the fact that the Polymerase Chain Reaction (PCR) methods, currently widely used, are extremely sensitive and specific. They are based on the multiplication of the isolated pathogen DNA and its identification by electrophoresis or DNA-chips. Even if analytical kits are already on the market, the project states, standardisation and validation of routine analysis is needed.
The 35 participating laboratories are currently focusing on 5 major pathogens: Salmonella, Campylobacter, enterohemorrhagic E. coli(EHEC), Listeria monocytogenes, and Yersinia enterocolitica from poultry-carcass rinse, pig-carcass swabs and milk.
The project recently reported that the most important outcome of the first year of the project has been the production of a guideline and a biochemical kit for validation of different types and brands of thermocyclers.
A simple method for purifying DNA from bacterial cultures has also been developed. Reference DNA material has been produced, and will be available at IRMM, Joint Research Center. An online PCR database is currently under construction. Future developments include the organisation of workshops for end users, and preparation of standardised guidelines in collaboration with CEN.
Further details concerning project QLK1-1999-00226 (FOOD-PCR) can be obtained from the project co-ordinator, Dr. Jeffrey Hoorfar Danish Veterinary Institute Bulowsvej 27DK-1790, Copenhagen.