A survey of Listeria in ready-to-eat food took place in Wales, United Kingdom, between February 2008 and January 2009. In total, 5,840 samples were taken and examined for the presence of Listeria species, including L. monocytogenes. Samples were tested using detection and enumeration methods, and the results were compared with current United Kingdom guidelines for the microbiological quality of ready-to-eat foods. The majority of samples were negative for Listeria by both direct plating and enriched culture. Seventeen samples (0.29%) had countable levels of Listeria species (other than L. monocytogenes), and another 11 samples (0.19%) had countable levels of L. monocytogenes. Nine samples (0.15%) were unsatisfactory or potentially hazardous when compared with United Kingdom guideline limits; six (0.10%) were in the unsatisfactory category (>100 CFU/g) for Listeria species (other than L. monocytogenes), and three (0.05%) were in the unacceptable or potentially hazardous category (>100 CFU/g) for L. monocytogenes. All three of these samples were from sandwiches (two chicken sandwiches and one ham-and-cheese sandwich). The most commonly isolated serotype of L. monocytogenes was 1/2a. This survey was used to determine the current prevalence of Listeria species and L. monocytogenes in ready-to-eat foods sampled from the point of sale in Wales.

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A study of the microbiological quality of cooked, sliced vacuum-packed meat was undertaken. Three hundred and eighty-one samples were taken (127 sets of three samples) from 55 commercial premises that produced packets of sliced, cooked, vacuum-packed meat for retail sale. The set of three samples consisted of one from the unsliced, cooked meat, one from the sliced product immediately after slicing, and one sliced packet for end of shelf-life testing. Samples were examined for aerobic colony count (ACC), Enterobacteriaceae, Escherichia coli, Listeria, and Salmonella. When compared to current UK guidelines for the quality of ready to eat food, samples were found to be unsatisfactory for ACC, Enterobacteriaceae, and E. coli. Unsatisfactory rates increased at the end of shelf-life compared to the unsliced meat sample results. No samples were positive for Listeria monocytogenes or Salmonella. This data is important for producers setting the shelf-life of their products.

The Welsh Food Microbiological Forum "shopping basket" survey is a long running, structured surveillance program examining ready-to-eat food randomly sampled from the point of sale or service in Wales, United Kingdom. The annual unsatisfactory rates for selected indicators and pathogens for 1998 through 2008 were examined. All the annual unsatisfactory rates for the selected pathogens were <0.5%, and no pattern with the annual rate was observed. There was also no discernible trend observed for the annual rates of Listeria spp. (not moncytogenes), with all rates <0.5%. However, there was a trend observed for Esherichia coli, with a decrease in rate between 1998 and 2003, rapid in the first few years, and then a gradual increase in rate up to 2008. It was concluded that there was no discernible pattern to the annual unsatisfactory rates for Listeria spp. (not monocytogenes), L. monocytogenes, Staphylococcus aureus, and Bacillus cereus, but that a definite trend had been observed for E. coli.