Occurrence of Listeria monocytogenes in sandwiches available to hospital patients in Wales, United Kingdom.

A survey for the presence of Listeria monocytogenes in hospital sandwiches was carried out in Wales, United Kingdom, between October 2005 and March 2006. The main aim of the survey was to establish the baseline rate of L. monocytogenes in hospital sandwiches after an outbreak of listeriosis among hospital patients in 2004 was epidemiologically linked to the consumption of contaminated sandwiches. The overall positive rate found in hospital sandwiches was 2.84% for enriched culture and 0.21% for direct counts. The unsatisfactory rate (> 100 CFU/g) for hospital sandwiches was 0.1%. The conclusion was that hospital sandwiches generally presented a low hazard to consumers. In addition to establishing the overall baseline and the unsatisfactory rates in hospital sandwiches in Wales for this period, the study compared the rates found in hospital sandwiches with the rates found in sandwiches simultaneously sampled from general retailers. The aim of this part of the study was to compare the relative rates associated with hospital and retail sandwiches to ascertain if there were any differences in the positive rate. The conclusion of this part of the survey was that there was not a statistically significant difference in rates between sandwiches sampled from hospitals and those sampled from general retailers.