ACMSF Minutes: 25 September 2008

Meeting held at Aviation House, 125 Kingsway, London WC2B 6NH


Chair: Professor S O’Brien

Mrs V Buller
Prof J Coia
Mrs R Glazebrook
Dr R Holliman
Professor Paul Hunter
Mr A Kyriakides
Mr P McMullin
Dr S Millership
Mrs J Morris
Prof P Williams

Mr S Wyllie (Defra)
Dr J Hilton (FSA)

Secretariat :
Dr L Foster (Administrative Secretary)
Dr P Cook (Scientific Secretary)
Mr A Adeoye
Miss S Butler

Members of the public:
Steve Batchford, Brakes
Roy Betts, CCFRA
Fiona Brookes, Northern Foods
Bridgette Clarke, Bakkavor Ltd
Andrew Curtis, Food and Drink Federation
Jane Duddle, British Retail Consortium
Kaarin Goodburn, Chilled Food Association
Kathie Grant, Health Protection Agency
Thelma Hooper, Al Control Laboratories
Jenny Hopwood, Marks and Spencer
Katy Hutton, Health Protection Agency
Christopher Jackson, Macrae Edinburgh Ltd
Karen Job, Marks and Spencer
Lisa Jones, Brakes
Samantha Kirk, Tesco
Ed Komorowski, Dairy UK
Alan Long, VEGA
Charmaine McGowan, Food Safety Promotion Board, Ireland
Cliff Morrison, Young’s Bluecrest
Rick Pendrous, Food Manufacture Magazine
Bernard Rowe, Consultant
Michael Wood, Bodycote
Simon Woods, G’s Marketing

1. Chair’s introduction

1.1 The Chair welcomed ACMSF Members and members of the public to the 68th meeting of the Committee. She also welcomed Dr Bob Adak (HPA) who would be presenting agenda item 6, Dr Chun-Han Chan (FSA) who would be presenting agenda item 8 and Ms Gael O’Neill (FSA) who would be presenting agenda item 9.

1.2 She asked Members to identify any items for discussion under any other business at the end of the meeting. None were raised.

2.Apologies for absence

2.1 Apologies for absence were received from Mr John Bassett, Dr David Brown, Professor Mike Gasson, Professor Tom Humphrey, Dr S Neill and Mr Robert Rees.

3. Declarations of interests

3.1 The Chair reminded the Committee of the need to declare any conflicts of interests relating to items on the agenda. She informed Members that, in relation to agenda item 9, she and Sally Millership were involved in one of the projects considered as part of the B14 Foodborne Diseases Research programme Review. Mr Kyriakides informed Members that in relation to agenda items 6-8, Sainsburys sold products likely to be considered under these agenda items.

4. Minutes of the 67th meeting (ACM/MIN/67)

4.1 Members approved ACM/MIN/67 as a correct record of the previous meeting subject to a small amendment to paragraph 7.7 to reflect ACMSF’s request for an interim update on the IID2 study prior to its completion in 2010. The Secretariat was asked to arrange for the final minutes to be posted on the Committee’s website.

Action: Secretariat

5. Matters arising

5.1 The Chair drew attention to the Secretariat information paper ACM/921 detailing matters arising from previous meetings. Members requested that the action relating to paragraph 7.7 on the IID2 study be amended to reflect the above change to the Minutes.

Action: Secretariat

6. Microbiological status of ready to eat foods (ACM/922 and parts a-d)

6.1 At the Chair’s invitation, Dr Bob Adak (HPA) introduced paper ACM/922. He presented an overview of public health issues arising from the microbiological contamination of ready to eat (RTE) fresh produce. He outlined outbreaks and incidents covering listeriosis linked to sandwiches from hospitals, kitchen hygiene (cross contamination and infected food handlers) and geographically dispersed outbreaks attributable to RTE fruit and vegetables during production, processing and distribution. He also reviewed the total number of reported outbreaks linked to RTE fresh produce from 1992-2007 and outlined the key stages involved in investigating these outbreaks.

6.2 In the ensuing discussion Members considered that:

  • Interaction of pathogens with plant material was important, as highlighted in a paper recently published by Shaw et al;
  • Molecular techniques including routine molecular typing of Salmonella isolates, such as that carried out in Scotland, was helpful in investigating outbreaks;
  • Partnership working between the food industry, enforcement authorities and Government Agencies was key to the successful trace-back of outbreaks. Members emphasised the need for engagement between industry and these authorities and commented that it was also important to work with statisticians to ensure statistical outputs were understood by all parties involved in the outbreak;
  • Most foodborne outbreaks were linked to contamination occurring in the kitchen. A substantial proportion of these outbreaks were due to transmission of noroviruses via infected food handlers. However it was recognised that, due to under-reporting of cases, it was difficult to ascertain exact figures;
  • Bacteria and viruses were difficult to control. For some outbreaks (e.g. Salmonella Senftenberg contaminated fresh basil) use of tight control measures throughout the production process did not prevent the outbreak occurring;
  • Use of trawling questionnaires in outbreaks to gather exposure information provided limited evidence linking outbreaks back to the contamination source as these documents were time-consuming to complete.

6.3 The Committee discussed the presented outbreaks linked to listeriosis in sandwiches and the microbiological risks associated with sandwiches contracted in or made on site. Members commented that it was important to work with both hospital caterers and suppliers of hospital sandwiches to promote food hygiene messages.

6.4 The Chair thanked Dr Adak for his presentation. She commented that the data had shown that a fairly low percentage of outbreaks were linked to salad vegetables. She concluded that the Committee had highlighted the need for a partnership approach to outbreak investigations and that HPA consider developing a lay guide on outbreak investigation statistics. ACMSF had also noted that routine molecular typing was helpful in rapidly resolving outbreaks and that under-ascertainment of norovirus infections might be greater than suggested by the available data. Members also considered that it was important not to be blinded by biological plausibility when investigating outbreaks. Lastly, she requested that HPA provide an update on the microbiological status of RTE foods at a future meeting.

Action: Secretariat/HPA

7. Report on Listeria in the elderly (ACM/923)

7.1 In the absence of Professor Humphrey (Chair, Ad hoc Group on Vulnerable Groups), at the Chair’s invitation, Dr Holliman introduced paper ACM/923. He explained that the Ad hoc group on Vulnerable Groups was set up following HPA’s notification to ACMSF of a change in the epidemiology of human Listeria monocytogenes infection in England and Wales. The Group was initially chaired by Professor Hunter (until his secondment in February 2008) and latterly by Professor Humphrey. The Group examined four hypotheses to examine the cause of the rise in listeriosis within a framework of hazard identification and characterisation. These were that:

(i) The rise in cases of listeriosis in compromised people over 60 years of age is an artefact associated with improved case recognition;

(ii) The population predominantly affected by the recent increase has become more susceptible to infection with L. monocytogenes;

(iii) The pathogen, L. monocytogenes has become more virulent and “new” strains are better able to cause bacteraemia in this age group of patients;

(iv) Levels of exposure have increased.

7.2 The Group concluded that:

Hypothesis 1
(i) From the available evidence, it was unlikely that the reported rise in listeriosis in the over 60s age group was an artefact. Whilst there had been some changes in medical practice and an increase in population, this was not sufficient to explain the change in epidemiology. The increase in reported cases of listeriosis was restricted to those patients with CNS infection. Similar rises were not observed in isolations from other body sites or associated with other foodborne pathogens. Hypothesis 1 was rejected.

Hypothesis 2
(ii) This age group were considered to be more susceptible to underlying conditions and treatment, and in theory, more susceptible to infection. However the overall increase in population ages 60 years or over was not considered to be a strong factor in terms of impacting on the rise in cases of listeriosis in this age group. Due to the lack of data available the hypothesis was not proven. The Group identified the need for targeted and focussed case-control studies to gather more information.

Hypothesis 3
(iii) There was no convincing information available to demonstrate that the virulence of strains of Listeria monocytogenes had changed. Molecular studies were needed to examine virulence factors to determine whether the change in epidemiology was linked to the virulence of the organism.

Hypothesis 4
(iv) Despite the availability of general information on listeria, there was a paucity of data relating to the over 60s age-group. Information on the behaviour of this age group in the home was lacking. Studies in the home were needed to examine how this age group bought, stored and selected food. Industry also needed to consider the impact of changes in shelf-life and preservative use on the survival and growth of listeria during food storage.

7.3 The Group also examined risk management issues linked to listeria. They concluded that:

  • There was a need for health education aimed at the over 60’s and for the development of information and advice about listeria focussing on this age Group. This should be to at least the same extent as the available information currently aimed at pregnant women;
  • Advice to industry on use of HACCP, temperature and shelf-life controls, hygiene and cleaning and food preservation needed to be reinforced.

7.4 Lastly, Dr Holliman thanked the members of the Group and those organisations who provided information to support the Group’s deliberations.

7.5 Members welcomed the report noting that is was drafted in a consumer-friendly format. They acknowledged that the Ad hoc Group had already provided the FSA with views to inform the development of recently revised advice on Listeria monocytogenes aimed at vulnerable groups including the over 60s. Some Committee Members cautioned that, in relation to members of the population with underlying conditions, not all drugs within one class would exert the same effect. A closer look was needed to examine the effects of individual drugs within one class. The Ad hoc Group confirmed that due to the lack of available data, it was not possible to examine this issue. Therefore the report recommended that carefully designed studies were carried out to explore this further.

7.6 The Committee endorsed the recommendations in the Report and recommended that the report be subjected to public consultation prior to final publication. Some Members suggested that the Secretariat send the report to relevant medical Committees as part of the consultation process to seek their views on the proposed studies.

Action: Secretariat

7.7 The Chair thanked Dr Holliman for his summary and for presenting the report at very short notice.

8. Survey of listeria in retail smoked fish (ACM/924)

8.1 At the Chair’s invitation, Dr Chun-Han Chan (FSA) presented paper ACM/924. She informed the Committee that the FSA published its survey of listeria contamination of retail smoked fish last week. This survey was commissioned to gather information on the prevalence of listeria contamination at retail. Dr Chan outlined the types of fish cuts sampled at retail, the sampling plan and methodology used in the survey. Of the 3222 samples tested, 378 samples overall were found to contain Listeria spp. giving a weighted prevalence of 10.5%. Of these L.monocytogenes was detected in 302 samples with a weighted prevalence of 8.3%. Of these samples 99.3% were satisfactory according to the Microbiological Criteria Regulations. Of the 1344 samples of cold smoked fish tested, 282 (20.5%) contained Listeria spp. and 236 (17.4%) contained L.monocytogenes all of which were present below the 100cfu/g limit in the Regulations. Of the 1878 hot smoked fish samples tested, 96 (5.2%) contained Listeria spp. and 66 (3.4%) contained L.monocytogenes. Three of these samples were in breach of the legal limit (>100 cfu/g) for L.monocytogenes. The Agency took appropriate action as soon as the results for these samples were reported and the affected products were recalled. No Salmonella was detected in any of the samples tested. Variations were found in retail storage temperatures ranging from -14ºC to 13.3ºC.

8.2 Members commented that it was reassuring that so few samples were found to be in breach of the Regulations, although 17% samples were found to contain Listeria monocytogenes, which highlighted the need for consumers to practice good food hygiene in the home. The variation in retail refrigeration cabinets was discussed. The FSA confirmed that a logistical regression was carried out to examine the effect of storage temperature on prevalence of Listeria monocytogenes. The results indicated that shelf-life did not appear to be an influencing factor on growth in this survey. Members acknowledged that it was difficult to correlate temperature data as the fridge temperature was not a reliable indicator of the temperature of the product. The reported correlation between the detection of Enterobacteriaceae and detection of listeria was discussed. One possible explanation for the correlation between detection of these organisms and Listeria spp. may have been due to the presence of faeces in the fish prior to evisceration.

8.3 The Committee welcomed the use of power calculations and a logical approach to defining sample size. The FSA confirmed that the confidence limits for prevalence on listeria in hot smoked and cold smoked fish were small. Details were presented in the full report.

8.4 Members discussed microbiological safety controls for smoked fish products and commented that it was unlikely that fish processing practices had changed since the survey was undertaken in 2006. Cold smoked fish was not subjected to heat processing to destroy potential contamination. Therefore controls depended on hygienic handling. Hot smoked fish was subjected to a pasteurisation process. Thus any contamination in hot-smoked fish was likely to occur at the post-pasteurisation stage.

8.5 Members considered whether the FSA’s advice on listeria in ready to eat foods for vulnerable groups needed to be revised in light of the survey findings. The Committee concluded that one could not assume smoked fish was a low-risk product purely on the basis that it was rarely associated with outbreaks. Members cautioned that the survey was not designed to inform advice to the public and that it would be premature for any new advice to target specific foods. As the processing of smoked fish and the incidence of Listeria monocytogenes were not believed to have changed markedly over the years it was considered possible that the handling and storage of smoked fish may be an important factor in relation to the microbiological safety risks.

8.6 The Chair thanked Dr Chan for her presentation. She also thanked Dr Chan for her contributions to ACMSF and wished her well in her new post. Summing up she emphasised that any advice should focus on good storage and handling practices. She suggested that ACMSF revisit the FSA’s listeria advice when more information from other surveys emerges.

Action: Secretariat/FSA

9. B14 Foodborne Diseases Research Programme

9.1 At the Chair’s invitation Ms O’Neill (FSA) briefed Members on the outcome of a review of the FSA’s research programme on foodborne diseases. She outlined the background to the programme which was developed to support the 2001 Foodborne Disease Strategy and was linked to the FSA’s target to reduce foodborne disease by 20% by 2006. The aim of the research review was to evaluate the achievements of the research programme against its ROAME. An independent panel of experts assessed 18 research projects carried out under the research programme against set criteria including scientific quality, value for money and policy relevance. Key outputs arising from the review included feed-back on how the FSA set and commissioned its research priorities. Future areas highlighted for investigation included Campylobacter and host factors impacting on disease causation. The proceedings from the review were expected to be published at the end of the year.

9.2 In the ensuing discussion, Members welcomed further work on Campylobacter highlighting that there was very little published information available on the survival of this organism in food.

9.3 The Chair thanked Ms O’Neill for her update.

10. Committee sub-groups

10.1 The Chair informed Members that, since the work of two of the sub-groups was covered on today's agenda, there was little additional work to report. The Working Group on Surveillance met earlier in the month to discuss the FSA’s survey of listeria contamination in smoked fish.

11. Dates of future meetings (ACM/925)

11.1 The Chair brought to Members’ attention paper ACM/925 which listed the dates for 2008 and 2009. She reminded Members that all meetings were open to members of the public.

12. Any other business

12.1 None were raised.

13. Public questions and answers

13.1 Dr Bernard Rowe (Member of the public) referred to the presentation on ready to eat foods (ACM/922). He expressed concern that failure to disclose information on pathogenic fingerprinting carried out by private laboratories may lead to delays in outbreak investigations. ACMSF Members agreed that where appropriate information should be shared to expedite investigations.

13.2 Mr Cliff Morrison (Chair, FDF seafood group) commented that processing controls and standards for smoked fish had not changed although companies had developed control document for Listeria monocytogenes aimed at smokers and growers. By developing a common HACCP control document companies aimed to achieve a good standard across the board.

13.3 Ms Kaarin Goodburn (CFA) queried whether the ACMSF had enough evidence in relation to variability in standards in different chilled food suppliers to target enforcers to raise industry standards to a common level. Members commented that whilst they would expect the highest standards to be applied across all sectors, in practice this was very difficult to achieve. Differences between enforcement of standards and good practice were also discussed.

13.4 Mr Alan Long (VEGA) queried whether methods used to wash bagged salads were effective in terms of removing liver fluke and addressing risks posed by Cryptosporidium. Members replied that washing could not be replied upon to remove liver fluke from watercress. Growing areas were kept away from contact with sheep, which can carry the parasite. Water contaminated with Cryptosporidium should not be used for drinking and washing ready to eat salads. In the event of an outbreak associated with this micro-organism, the water utility companies were required to issue advice.

13.5 Ed Komorowski (Dairy UK) commented that the listeria in the elderly report recommended that the FSA worked with industry to ensure that reduced salt levels did not impact on microbiological food safety. The Chair confirmed that the ACMSF had already looked at this issue in 2005.

13.6 Rick Pendrous (Food Manufacture magazine) commented on the variability of use by dates on perishable foods sold loose highlighted in the ACMSF’s listeria report. Members confirmed that this was an issue highlighted in the North West Survey of pre-sliced cooked meat which found that a high proportion of loose sold products were not labelled with durability indicators. The Ad hoc group considered that it was important that manufacturers and retailers provided this information as food sold loose to consumers could cause problems in terms of exceeding shelf life if use-by date information was not available. Thus the Ad hoc group recommended in its report that the FSA reviewed the need for consistent advice on loose-sold products.

13.7 Fiona Brooks (Northern Foods) commented that HPA’s presentation had shown that 27% of outbreaks were linked to infected food handlers and queried which pathogens were the cause of these outbreaks. Bob Adak (HPA) replied that most outbreaks were linked to noroviruses or parasites. Following the meeting he confirmed that Health Protection Agency surveillance data shows that investigators reported that infected food handlers were suspected to have contributed to the transmission of infection in 22 of the 83 outbreaks attributed to the consumption of salad vegetables and fruit. Within this subset of 22 outbreaks, a viral aetiology was confirmed or suspected in 15 (68%) outbreaks.

13.8 There being no further business, the Chair thanked Members and members of the public for attending and closed the meeting.