Detection, validation, and assessment of risks implied by the viable but non-culturable (VBNC) state of enteric bacterial pathogens in fresh produce

More fresh fruits and vegetables are grown, sold and eaten today than at any other time in history. Unfortunately, outbreaks of food poisoning caused by pathogenic bacteria in fresh produce are also more common than in the past. Products are routinely analyzed to ensure that they are free of such bacteria, but some are very difficult to find because they do not grow on media used by quality control laboratories. These are known as “viable but non-culturable” (VBNC) bacteria. We will develop a new, inexpensive and easy-to-use method based on the well-known PCR reaction to make it possible for quality control laboratories to detect two important pathogens in fresh produce, Salmonella and E. coli, even when they are in the difficult-to-find VBNC form. The performance of the new method will be checked through field trials and pilot plant experiments with leaf lettuce. Information from these experiments will be used to reveal how likely fresh produce is to be contaminated with VBNC pathogens during production and after harvest. Therefore, this research will contribute to an important new laboratory method and key information to support on-going efforts by the industry to improve the safety of fresh fruits and vegetables.