Campylobacter in ready to eat foods: results of a Welsh survey Meldrum RJ * and Smith R + (on behalf of the Welsh Food Microbiological Forum) * Food Scientist, PHLS in Wales + Clinical Scientist, CDSC Wales Fresh herbs Fresh soft fruit Poultry meals Tuna sandwiches Ham sandwiches
Meldrum RJ * and Smith R+(on behalf of the Welsh Food Microbiological Forum)
* Food Scientist, PHLS in Wales
+ Clinical Scientist, CDSC Wales
Fresh soft fruit
Desserts made with shell eggs
Fresh cream cakes
Egg mayonnaise sandwiches
Rice or pasta based salads
The Welsh Food Microbiological Forum (WFMF) is an all Wales body with representation from Local Authorities, FSA Wales and the PHLS in Wales. It coordinates the sampling and examination of ready to eat foods on an all Wales basis through a randomised shopping basket programme. The shopping basket model used by the WFMF in Wales relies on a nominated list of foods that are randomly sampled by all participating Local Authorities for one year, although foods of interest can be sampled for longer, as required. Foods to be sampled are regularly reviewed at WFMF meetings and are usually selected as being those of particular interest to Local Authorities, FSA Wales and the PHLS in Wales. Foods are removed when it is considered that there has been enough data collected, but may be included again at a later stage.
It was recognized from the very beginning of the shopping basket programme that taking samples on an ad hoc basis from premises that a sampling officer had chosen introduced bias into the programme and therefore randomised sampling was introduced. As well as avoiding bias, random selection of premises also increased the variety of outlets sampled, to include restaurants, schools, garage forecourt shops and works canteens.
At the beginning of October 2000 testing for Campylobacter was introduced for the shopping basket that was being sampled at the time, in response to a need to estimate the level of Campylobacter contamination in ready to eat foods available to Welsh consumers. The range of foods tested over the fifteen months spanned two shopping basket and included chicken and chicken products, egg products, ham and pork, all of which could be potential sources of Campylobacter. Table 1 details the actual range of foods tested. Testing for Campylobacter ceased in January 2002 in light of the results found.
During the fifteen months (October 2000-January 2002) of the examination for Campylobacter, 1727 usable sample datasets were returned to CDSC Wales by nine of the twenty-two local authorities in Wales. No Campylobacter was found in any of these samples. It is also estimated that in addition to the 1727 datasets returned to CDSC Wales, there were at least another 4000 food samples submitted to PHLS in Wales for examination. It is known that no Campylobacter was found in any of these samples.
The datasets returned to CDSC Wales were analysed by month sampled, area sampled and food type, based upon the food types defined by the latest PHLS guidelines for ready to eat foods sampled at the point of sale.
% samples taken
Table 1 The range of ready to eat foods tested for Campylobacter
% samples taken
Ready To Eat
% samples taken
The negative results found in the survey for Campylobacter in ready to eat foods available to consumers in Wales is considered significant. The pathogen could not be detected in any of the ready to eat foods that were randomly sampled and therefore there is a degree of confidence in stating that the range of ready to eat foods that were sampled are not a significant source of the organism. The results of the survey help to focus attention onto other possible sources of the organism, as there are still cases of Campylobacter cases occurring in Wales at approximately 115 cases per 100,000 population. It can be inferred then that there must be other sources of the organism, including other food-related sources such as other ready to eat foods not sampled as part of the shopping basket, cross contamination or insufficient cooking within the domestic and catering environments. A more focussed study is planned.
As part of the shopping basket programme, participating Local Authorities delivered shopping basket samples to one of four Welsh PHLS laboratories. Samples were examined for a variety of analytes, including aerobic colony count, various indicators and various pathogens, including Campylobacter. Standard PHLS methods were used for all analytes. Results of the bacteriological examination were returned directly to the Local Authority. Local Authorities recorded the results and sample information, and then electronically transmitted the information to CDSC Wales where the WFMF database is housed, for collation and analysis. The WFMF database was searched for data pertaining to the examination for Campylobacter for the period concerned.