A Sustainability Compass for policy navigation to sustainable food systems

Growing acknowledgement that food systems require transformation, demands comprehensive sustainability assessments that can support decision-making and sustainability governance. To do so, assessment frameworks must be able to make trade-offs and synergies visible and allow for inclusive negotiation on food system outcomes relevant to diverse food system actors. This paper reviews literature and frameworks and builds on stakeholder input to present a Sustainability Compass made up of a comprehensive set of metrics for food system assessments. The Compass defines sustainability scores for four societal goals, underpinned by areas of concern. We demonstrate proof of concept of the operationalization of the approach and its metrics. The Sustainability Compass is able to generate comprehensive food system insights that enables reflexive evaluation and multi-actor negotiation for policy making.

Updated quantitative risk assessment (QRA) of the BSE risk posed by processed animal protein (PAP)

EFSA was requested: to assess the impact of a proposed quantitative real-time polymerase chain reaction (qPCR) 'technical zero' on the limit of detection of official controls for constituents of ruminant origin in feed, to review and update the 2011 QRA, and to estimate the cattle bovine spongiform encephalopathy (BSE) risk posed by the contamination of feed with BSE-infected bovine-derived processed animal protein (PAP), should pig PAP be re-authorised in poultry feed and vice versa, using both light microscopy and ruminant qPCR methods, and action limits of 100, 150, 200, 250 and 300 DNA copies. The current qPCR cannot discriminate between legitimately added bovine material and unauthorised contamination, or determine if any detected ruminant material is associated with BSE infectivity. The sensitivity of the surveillance for the detection of material of ruminant origin in feed is currently limited due to the heterogeneous distribution of the material, practicalities of sampling and test performance. A 'technical zero' will further reduce it. The updated model estimated a total BSE infectivity four times lower than that estimated in 2011, with less than one new case of BSE expected to arise each year. In the hypothetical scenario of a whole carcass of an infected cow entering the feed chain without any removal of specified risk material (SRM) or reduction of BSE infectivity via rendering, up to four new cases of BSE could be expected at the upper 95th percentile. A second model estimated that at least half of the feed containing material of ruminant origin will not be detected or removed from the feed chain, if an interpretation cut-off point of 100 DNA copies or more is applied. If the probability of a contaminated feed sample increased to 5%, with an interpretation cut-off point of 300 DNA copies, there would be a fourfold increase in the proportion of all produced feed that is contaminated but not detected.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 8: suitability of taxonomic units notified to EFSA until March 2018

The qualified presumption of safety (QPS) was developed to provide a harmonised generic pre‐evaluation procedure to support safety risk assessments of biological agents performed by EFSA's Scientific Panels. The identity, body of knowledge, safety concerns and antimicrobial resistance of valid taxonomic units were assessed. Safety concerns identified for a taxonomic unit are, where possible and reasonable in number, reflected by ‘qualifications’ which should be assessed at the strain level by the EFSA's Scientific Panels. During the current assessment, no new information was found that would change the previously recommended QPS taxonomic units and their qualifications. The Panel clarified that the qualification ‘for production purpose only’ implies the absence of viable cells of the production organism in the final product and can also be applied for food and feed products based on microbial biomass. Between September 2017 and March 2018, the QPS notification list was updated with 46 microorganisms from applications for market authorisation. From these, 28 biological agents already had QPS status, 15 were excluded of the QPS exercise from the previous QPS mandate (10 filamentous fungi and one bacteriophage) or from further evaluations within the current mandate (two notifications of Streptomyces spp. and one of Escherichia coli), and one was excluded where confirmatory data for the risk assessment of a plant protection product (PPP) was requested (Pseudomonas sp.). Three taxonomic units were (re)evaluated: Paracoccus carotinifaciens and Paenibacillus lentus had been previously evaluated in 2008 and 2014, respectively, and were now re‐evaluated within this mandate, and Yarrowia lipolytica, which was evaluated for the first time. P. carotinifaciens and P. lentus cannot be granted QPS status due to lack of scientific knowledge. Y. lipolytica is recommended for QPS status, but only for production purpose.

Evaluation of the application for a new alternative processing method for animal by-products of Category 3 material (ChainCraft B.V.)

EFSA received an application from the Dutch Competent Authority, under Article 20 of Regulation (EC) No 1069/2009 and Regulation (EU) No 142/2011, for the evaluation of an alternative method for treatment of Category 3 animal by‐products (ABP). It consists of the hydrolysis of the material to short‐carbon chains, resulting in medium‐chain fatty acids that may contain up to 1% hydrolysed protein, for use in animal feed. A physical process, with ultrafiltration followed by nanofiltration to remove hazards, is also used. Process efficacy has been evaluated based on the ability of the membrane barriers to retain potential biological hazards present. Small viruses passing the ultrafiltration membrane will be retained at the nanofiltration step, which represents a Critical Control Point (CCP) in the process. This step requires the Applicant to validate and provide certification for the specific use of the nanofiltration membranes used. Continuous monitoring and membrane integrity tests should be included as control measures in the HACCP plan. The ultrafiltration and nanofiltration techniques are able to remove particles of the size of virus, bacteria and parasites from liquids. If used under controlled and appropriate conditions, the processing methods proposed should reduce the risk in the end product to a degree which is at least equivalent to that achieved with the processing standards laid down in the Regulation for Category 3 material. The possible presence of small bacterial toxins produced during the fermentation steps cannot be avoided by the nanofiltration step and this hazard should be controlled by a CCP elsewhere in the process. The limitations specified in the current legislation and any future modifications in relation to the end use of the product also apply to this alternative process, and no hydrolysed protein of ruminant origin (except ruminant hides and skins) can be included in feed for farmed animals or for aquaculture.

Listeria monocytogenes contamination of ready-to-eat foods and the risk for human health in the EU

Food safety criteria for Listeria monocytogenes in ready-to-eat (RTE) foods have been applied from 2006 onwards (Commission Regulation (EC) 2073/2005). Still, human invasive listeriosis was reported to increase over the period 2009-2013 in the European Union and European Economic Area (EU/EEA). Time series analysis for the 2008-2015 period in the EU/EEA indicated an increasing trend of the monthly notified incidence rate of confirmed human invasive listeriosis of the over 75 age groups and female age group between 25 and 44 years old (probably related to pregnancies). A conceptual model was used to identify factors in the food chain as potential drivers for L. monocytogenes contamination of RTE foods and listeriosis. Factors were related to the host (i. population size of the elderly and/or susceptible people; ii. underlying condition rate), the food (iii. L. monocytogenes prevalence in RTE food at retail; iv. L. monocytogenes concentration in RTE food at retail; v. storage conditions after retail; vi. consumption), the national surveillance systems (vii. improved surveillance), and/or the bacterium (viii. virulence). Factors considered likely to be responsible for the increasing trend in cases are the increased population size of the elderly and susceptible population except for the 25-44 female age group. For the increased incidence rates and cases, the likely factor is the increased proportion of susceptible persons in the age groups over 45 years old for both genders. Quantitative modelling suggests that more than 90% of invasive listeriosis is caused by ingestion of RTE food containing > 2,000 colony forming units (CFU)/g, and that one-third of cases are due to growth in the consumer phase. Awareness should be increased among stakeholders, especially in relation to susceptible risk groups. Innovative methodologies including whole genome sequencing (WGS) for strain identification and monitoring of trends are recommended.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 7: suitability of taxonomic units notified to EFSA until September 2017

The qualified presumption of safety (QPS) concept was developed to provide a harmonised generic pre-evaluation to support safety risk assessments of biological agents performed by EFSA's scientific Panels. The identity, body of knowledge, safety concerns and antimicrobial resistance of valid taxonomic units were assessed. Safety concerns identified for a taxonomic unit are, where possible and reasonable in number, considered to be 'qualifications' which should be assessed at the strain level by the EFSA's scientific Panels. No new information was found that would change the previously recommended QPS taxonomic units and their qualifications. The BIOHAZ Panel confirms that the QPS approach can be extended to a genetically modified production strain if the recipient strain qualifies for the QPS status, and if the genetic modification does not indicate a concern. Between April and September 2017, the QPS notification list was updated with 46 applications for market authorisation. From these, 14 biological agents already had QPS status and 16 were not included as they are filamentous fungi or enterococci. One notification of Streptomyces K-61 (notified as former S. griseoviridis) and four of Escherichia coli were not considered for the assessment as they belong to taxonomic units that were excluded from further evaluations within the current QPS mandate. Eight notifications of Bacillus thuringiensis and one of an oomycete are pending the reception of the complete application. Two taxonomic units were evaluated: Kitasatospora paracochleata, which had not been evaluated before, and Komagataella phaffii, previously notified as Pichia pastoris included due to a change in the taxonomic identity. Kitasatospora paracochleata cannot be granted QPS status due to lack of information on its biology and to its possible production of toxic secondary metabolites. The species Komagataella phaffii can be recommended for the QPS list when used for enzyme production.

Scientific opinion on chronic wasting disease (II)

The European Commission asked EFSA for a scientific opinion on chronic wasting disease in two parts. Part one, on surveillance, animal health risk-based measures and public health risks, was published in January 2017. This opinion (part two) addresses the remaining Terms of Reference, namely, 'are the conclusions and recommendations in the EFSA opinion of June 2004 on diagnostic methods for chronic wasting disease still valid? If not, an update should be provided', and 'update the conclusions of the 2010 EFSA opinion on the results of the European Union survey on chronic wasting disease in cervids, as regards its occurrence in the cervid population in the European Union'. Data on the performance of authorised rapid tests in North America are not comprehensive, and are more limited than those available for the tests approved for statutory transmissible spongiform encephalopathies surveillance applications in cattle and sheep. There are no data directly comparing available rapid test performances in cervids. The experience in Norway shows that the Bio-Rad TeSeE™ SAP test, immunohistochemistry and western blotting have detected reindeer, moose and red deer cases. It was shown that testing both brainstem and lymphoid tissue from each animal increases the surveillance sensitivity. Shortcomings in the previous EU survey limited the reliability of inferences that could be made about the potential disease occurrence in Europe. Subsequently, testing activity in Europe was low, until the detection of the disease in Norway, triggering substantial testing efforts in that country. Available data neither support nor refute the conclusion that chronic wasting disease does not occur widely in the EU and do not preclude the possibility that the disease was present in Europe before the survey was conducted. It appears plausible that chronic wasting disease could have become established in Norway more than a decade ago.

Evaluation of the Application for new alternative biodiesel production process for rendered fat of Cat 1 (BDI-RepCat process, AT)

A new alternative method for the production of biodiesel from rendered fat of all categories of animal by‐products was assessed. The process was compared to the approved biodiesel production process described in Chapter IV Section 2 D of Annex IV of Commission Regulation (EU) 142/2011. Tallow derived from Category 1 material is treated according to Method 1 from the same Regulation (133°C, 20 min, 3 bar) and subsequently mixed with 15% methanol, heated to reaction temperature (220°C) in several heat exchangers and transferred into the continuous conversion reactor by means of a high pressure pump (80 bar) for 30 min. In the conversion phase, there is an exposure to methanol in the absence of alkaline or acidic conditions. The impact of this procedure on the thermostability of transmissible spongiform encephalopathy (TSE) has not been assessed in the literature. After the reaction, the biodiesel/glycerol mixture is distilled under vacuum at a minimum temperature of 150°C and a maximum pressure of 10 mbar, which is equivalent to the distillation step in the approved biodiesel production process, for which a 3 log₁₀ reduction factor in PrP27–30 was obtained. Therefore, a similar level of TSE infectivity reduction could be expected for that phase of the method. A previous EFSA Opinion established that a reduction of 6 log₁₀ in TSE infectivity should be achieved by any proposed alternative method in order to be equivalent to the approved processing method. This level of reduction has not been shown with experimental trials run under conditions equivalent to the ones described for the RepCat process. It was not possible to conclude whether or not the level of TSE infectivity reduction in the RepCat process is at least of 6 log₁₀. Therefore, it was also not possible to conclude about the equivalence with the approved biodiesel production process.

Guidance on the requirements for the development of microbiological criteria

The European Food Safety Authority asked the Panel on Biological Hazards (BIOHAZ) to deliver a scientific opinion providing: (i) a review of the approaches used by the BIOHAZ Panel to address requests from risk managers to suggest the establishment of microbiological criteria; (ii) guidance on the required scientific evidence, data and methods/tools necessary for considering the development of microbiological criteria for pathogenic microorganisms and indicator microorganisms; (iii) recommendations on methods/tools to design microbiological criteria and (iv) guidelines for the requirements and tasks of risk assessors, compared to risk managers, in relation to microbiological criteria. This document provides guidance on approaches when: (i) a quantitative microbial risk assessment (QMRA) is available, (ii) prevalence and concentration data are available, but not a QMRA model, and (iii) neither a QMRA nor prevalence and/or concentration data are available. The role of risk assessors should be focused on assessing the impact of different microbiological criteria on public health and on product compliance. It is the task of the risk managers to: (1) formulate unambiguous questions, preferably in consultation with risk assessors, (2) decide on the establishment of a microbiological criterion, or target in primary production sectors, and to formulate the specific intended purpose for using such criteria, (3) consider the uncertainties in impact assessments on public health and on product compliance and (4) decide the point in the food chain where the microbiological criteria are intended to be applied and decide on the actions which should be taken in case of non‐compliance. It is the task of the risk assessors to support risk managers to ensure that questions are formulated in a way that a precise answer can be given, if sufficient information is available, and to ensure clear and unambiguous answers, including the assessment of uncertainties, based on available scientific evidence.

Genetic resistance to transmissible spongiform encephalopathies (TSE) in goats

Breeding programmes to promote resistance to classical scrapie, similar to those for sheep in existing transmissible spongiform encephalopathies (TSE) regulations, have not been established in goats. The European Commission requested a scientific opinion from EFSA on the current knowledge of genetic resistance to TSE in goats. An evaluation tool, which considers both the weight of evidence and strength of resistance to classical scrapie of alleles in the goat PRNP gene, was developed and applied to nine selected alleles of interest. Using the tool, the quality and certainty of the field and experimental data are considered robust enough to conclude that the K222, D146 and S146 alleles both confer genetic resistance against classical scrapie strains known to occur naturally in the EU goat population, with which they have been challenged both experimentally and under field conditions. The weight of evidence for K222 is greater than that currently available for the D146 and S146 alleles and for the ARR allele in sheep in 2001. Breeding for resistance can be an effective tool for controlling classical scrapie in goats and it could be an option available to member states, both at herd and population levels. There is insufficient evidence to assess the impact of K222, D146 and S146 alleles on susceptibility to atypical scrapie and bovine spongiform encephalopathy (BSE), or on health and production traits. These alleles are heterogeneously distributed across the EU Member States and goat breeds, but often at low frequencies (< 10%). Given these low frequencies, high selection pressure may have an adverse effect on genetic diversity so any breeding for resistance programmes should be developed at Member States, rather than EU level and their impact monitored, with particular attention to the potential for any negative impact in rare or small population breeds.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 6: suitability of taxonomic units notified to EFSA until March 2017

The qualified presumption of safety (QPS) concept was developed to provide a harmonised generic pre‐evaluation to support safety risk assessments of biological agents performed by EFSA's scientific Panels. The identity, body of knowledge, safety concerns and antimicrobial resistance of valid taxonomic units were assessed. Safety concerns identified for a taxonomic unit are, where possible and reasonable in number, reflected as ‘qualifications’ which should be assessed at the strain level by the EFSA's scientific Panels. No new information was found that would change the previously recommended QPS taxonomic units and their qualifications. Between the end of September 2016 and March 2017, the QPS notification list was updated with 87 applications for market authorisation. From these, 32 biological agents already had a QPS status, and 37 were not included in the evaluation as they are filamentous fungi or enterococci. Streptomyces species (Streptomyces cinnamonensis, Streptomyces mobaraensis and Streptomyces violaceoruber), Bacillus circulans (three notifications) and Escherichia coli (seven notifications) were re‐confirmed not suitable for QPS. Streptomyces rubiginosus and Streptomyces netropsis, not evaluated within the previous mandate, were also not recommended for QPS. Streptomyces spp. and E. coli will be excluded from further QPS evaluations within the current QPS mandate. Hyphomicrobium denitrificans, which has never been evaluated before, was not recommended for the QPS list and for Pseudomonas amyloderamosa, the QPS assessment was not applicable because it is not a validated species. Lactobacillus animalis was a new taxonomic unit recommended to have the QPS status.

Bovine spongiform encephalopathy (BSE) cases born after the total feed ban

Sixty bovine spongiform encephalopathy (BSE) cases of Classical or unknown type (BARB‐60 cases) were born after the date of entry into force of the EU total feed ban on 1 January 2001. The European Commission has requested EFSA to provide a scientific opinion on the most likely origin(s) of these BARB‐60 cases; whether feeding with material contaminated with the BSE agent can be excluded as the origin of any of these cases and, if so, whether there is enough scientific evidence to conclude that such cases had a spontaneous origin. The source of infection cannot be ascertained at the individual level for any BSE case, including these BARB‐60 cases, so uncertainty remains high about the origin of disease in each of these animals, but when compared with other biologically plausible sources of infection (maternal, environmental, genetic, iatrogenic), feed‐borne exposure is the most likely. This exposure was apparently excluded for only one of these BARB‐60 cases. However, there is considerable uncertainty associated with the data collected through the field investigation of these cases, due to a time span of several years between the potential exposure of the animal and the confirmation of disease, recall difficulty, and the general paucity of documented objective evidence available in the farms at the time of the investigation. Thus, feeding with material contaminated with the BSE agent cannot be excluded as the origin of any of the BARB‐60 cases, nor is it possible to definitively attribute feed as the cause of any of the BARB‐60 cases. A case of disease is classified as spontaneous by a process of elimination, excluding all other definable possibilities; with regard to the BARB‐60 cases, it is not possible to conclude that any of them had a spontaneous origin.

Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.

Scientific Opinion on the update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA

EFSA is requested to assess the safety of a broad range of biological agents in the context of notification for market authorisation as sources of food and feed additives, food enzymes and plant protection products. The qualified presumption of safety (QPS) assessment was developed to provide a harmonised generic pre-assessment to support safety risk assessments performed by EFSA's scientific Panels. The safety of unambiguously defined biological agents (at the highest taxonomic unit appropriate for the purpose for which an application is intended), and the completeness of the body of knowledge are assessed. Identified safety concerns for a taxonomic unit are, where possible and reasonable in number, reflected as 'qualifications' in connection with a recommendation for a QPS status. The list of QPS recommended biological agents was reviewed and updated in the current opinion and therefore becomes the valid list. The 2016 update reviews previously assessed microorganisms including bacteria, yeasts and viruses used for plant protection purposes following an Extensive Literature Search strategy. The taxonomic units related to the new notifications received since the 2013 QPS opinion, were periodically evaluated for a QPS status and the results published as Statements of the BIOHAZ Panel. Carnobacterium divergens, Lactobacillus diolivorans, Microbacterium imperiale, Pasteuria nishizawae, Pediococcus parvulus, Bacillus flexus, Bacillus smithii, Xanthomonas campestris and Candida cylindracea were recommended for the QPS list. All taxonomic units previously recommended for the 2013 QPS list had their status reconfirmed as well their qualifications with the exception of Pasteuria nishizawae for which the qualification was removed. The exclusion of filamentous fungi and enterococci from the QPS evaluations was reconsidered but monitoring will be maintained and the status will be re-evaluated in the next QPS Opinion update. Evaluation of bacteriophages should remain as a case-by-case procedure and should not be considered for QPS status.

Hazard analysis approaches for certain small retail establishments in view of the application of their food safety management systems

Under current European hygiene legislation, food businesses are obliged to develop and implement food safety management systems (FSMS) including prerequisite programme (PRP) activities and hazard analysis and critical control point principles. This requirement is especially challenging for small food retail establishments, where a lack of expertise and other resources may limit the development and implementation of effective FSMS. In this opinion, a simplified approach to food safety management is developed and presented based on a fundamental understanding of processing stages (flow diagram) and the activities contributing to increased occurrence of the hazards (biological, chemical (including allergens) or physical) that may occur. The need to understand and apply hazard or risk ranking within the hazard analysis is removed and control is achieved using PRP activities as recently described in the European Commission Notice 2016/C278, but with the addition of a PRP activity covering ‘product information and customer awareness’. Where required, critical limits, monitoring and record keeping are also included. Examples of the simplified approach are presented for five types of retail establishments: butcher, grocery, bakery, fish and ice cream shop.

Update of the list of QPS-recommended biological agents intentionally added to food or feed as notified to EFSA 5: suitability of taxonomic units notified to EFSA until September 2016

EFSA was requested to assess the safety of a broad range of biological agents in the context of notifications for market authorisation as sources of food and feed additives, enzymes and plant protection products. The qualified presumption of safety (QPS) assessment was developed to provide a harmonised generic pre-assessment to support safety risk assessments performed by EFSA's Scientific Panels. The safety of unambiguously defined biological agents (at the highest taxonomic unit appropriate for the purpose for which an application is intended) and the completeness of the body of knowledge were assessed. Safety concerns identified for a taxonomic unit are, where possible and reasonable in number, reflected as 'qualifications' in connection with a recommendation for a QPS status. A total of 57 biological agents were notified to EFSA between the end of April 2016 and the beginning of September 2016. From these, 34 biological agents already had a QPS status and did not require further evaluation, and 10 were not included in the evaluation as they are filamentous fungi or enterococci, biological groups which have been excluded from QPS evaluation since 2014. Three notifications for Streptomyces violaceoruber, one for Streptomyces albus, one for Bacillus circulans and four for Escherichia coli were not evaluated for QPS status because these species were recently assessed and considered not suitable for QPS status. Therefore, only four notifications related to three taxonomic units were evaluated for QPS status. Of these, Arthrobacter ramosus and Pseudomonas fluorescens are not recommended for the QPS list. Bacillus smithii is recommended for the QPS status.

Risk for the development of Antimicrobial Resistance (AMR) due to feeding of calves with milk containing residues of antibiotics

EFSA was requested to: 1) assess the risk for the development of antimicrobial resistance (AMR) due to feeding on farm of calves with colostrum potentially containing residues of antibiotics; 2) assess the risk for the development of AMR due to feeding on farm of calves with milk of cows treated during lactation with an antibiotic and milked during the withdrawal period, and 3) propose possible options to mitigate the risk for the development of AMR derived from such practices. Treatment of dairy cows during the dry period and during lactation is common in the EU Member States. Penicillins, alone or in combination with aminoglycosides, and cephalosporins are most commonly used. Residue levels of antimicrobials decrease with the length of the dry period. When the interval from the start of the drying-off treatment until calving is as long as or longer than the minimum specified in the Summary of Product Characteristics of the antimicrobial, faecal shedding of antimicrobial-resistant bacteria will not increase when calves are fed colostrum from treated cows. Milk from cows receiving antimicrobial treatment during lactation contains substantial residues during the treatment and withdrawal period. Consumption of such milk will lead to increased faecal shedding of antimicrobial-resistant bacteria by calves. A range of possible options exist for restricting the feeding of such milk to calves, which could be targeting the highest priority critically important antimicrobials. β-Lactamases can reduce the concentration of β-lactams which are the most frequently used antimicrobials in milking cows. Options to mitigate the presence of resistant bacteria in raw milk or colostrum are mainly based on thermal inactivation.

Chronic wasting disease (CWD) in cervids

In April and May of 2016, Norway confirmed two cases of chronic wasting disease (CWD) in a wild reindeer and a wild moose, respectively. In the light of this emerging issue, the European Commission requested EFSA to recommend surveillance activities and, if necessary, additional animal health risk-based measures to prevent the introduction of the disease and the spread into/within the EU, specifically Estonia, Finland, Iceland, Latvia, Lithuania, Norway, Poland and Sweden, and considering seven wild, semidomesticated and farmed cervid species (Eurasian tundra reindeer, Finnish (Eurasian) forest reindeer, moose, roe deer, white-tailed deer, red deer and fallow deer). It was also asked to assess any new evidence on possible public health risks related to CWD. A 3-year surveillance system is proposed, differing for farmed and wild or semidomesticated cervids, with a two-stage sampling programme at the farm/geographically based population unit level (random sampling) and individual level (convenience sampling targeting high-risk animals). The current derogations of Commission Implementing Decision (EU) 2016/1918 present a risk of introduction of CWD into the EU. Measures to prevent the spread of CWD within the EU are dependent upon the assumption that the disease is already present; this is currently unknown. The measures listed are intended to contain (limit the geographic extent of a focus) and/or to control (actively stabilise/reduce infection rates in an affected herd or population) the disease where it occurs. With regard to the zoonotic potential, the human species barrier for CWD prions does not appear to be absolute. These prions are present in the skeletal muscle and other edible tissues, so humans may consume infected material in enzootic areas. Epidemiological investigations carried out to date make no association between the occurrence of sporadic Creutzfeldt-Jakob disease in humans and exposure to CWD prions.

EMA and EFSA Joint Scientific Opinion on measures to reduce the need to use antimicrobial agents in animal husbandry in the European Union, and the resulting impacts on food safety (RONAFA)

EFSA and EMA have jointly reviewed measures taken in the EU to reduce the need for and use of antimicrobials in food-producing animals, and the resultant impacts on antimicrobial resistance (AMR). Reduction strategies have been implemented successfully in some Member States. Such strategies include national reduction targets, benchmarking of antimicrobial use, controls on prescribing and restrictions on use of specific critically important antimicrobials, together with improvements to animal husbandry and disease prevention and control measures. Due to the multiplicity of factors contributing to AMR, the impact of any single measure is difficult to quantify, although there is evidence of an association between reduction in antimicrobial use and reduced AMR. To minimise antimicrobial use, a multifaceted integrated approach should be implemented, adapted to local circumstances. Recommended options (non-prioritised) include: development of national strategies; harmonised systems for monitoring antimicrobial use and AMR development; establishing national targets for antimicrobial use reduction; use of on-farm health plans; increasing the responsibility of veterinarians for antimicrobial prescribing; training, education and raising public awareness; increasing the availability of rapid and reliable diagnostics; improving husbandry and management procedures for disease prevention and control; rethinking livestock production systems to reduce inherent disease risk. A limited number of studies provide robust evidence of alternatives to antimicrobials that positively influence health parameters. Possible alternatives include probiotics and prebiotics, competitive exclusion, bacteriophages, immunomodulators, organic acids and teat sealants. Development of a legislative framework that permits the use of specific products as alternatives should be considered. Further research to evaluate the potential of alternative farming systems on reducing AMR is also recommended. Animals suffering from bacterial infections should only be treated with antimicrobials based on veterinary diagnosis and prescription. Options should be reviewed to phase out most preventive use of antimicrobials and to reduce and refine metaphylaxis by applying recognised alternative measures.

Inactivation of norovirus surrogates on surfaces and raspberries by steam-ultrasound treatment

Human disease outbreaks caused by norovirus (NoV) following consumption of contaminated raspberries are an increasing problem. An efficient method to decontaminate the fragile raspberries and the equipment used for processing would be an important step in ensuring food safety. A potential surface treatment that combines pressurized steam and high-power ultrasound (steam-ultrasound) was assessed for its efficacy to inactivate human NoV surrogates: coliphage (MS2), feline calicivirus (FCV), and murine norovirus (MNV) inoculated on plastic surfaces and MS2 inoculated on fresh raspberries. The amounts of infectious virus and viral genomes were determined by plaque assay and reverse transcription-real time quantitative PCR (RT-qPCR), respectively. On plastic surfaces, an inactivation of >99.99% was obtained for both MS2 and FCV, corresponding to a 9.1-log and >4.8-log reduction after 1 or 3 s of treatment, respectively; while a 3.7-log (99.9%) reduction of MNV was reached after 3 s of treatment. However, on fresh raspberries only a 1-log reduction (∼89%) of MS2 could be achieved after 1 s of treatment, at which point damage to the texture of the fresh raspberries was evident. Increasing treatment time (0 to 3 s) resulted in negligible reductions of viral genome titers of MS2, FCV, and MNV on plastic surfaces as well as of MS2 inoculated on raspberries. Steam-ultrasound treatment in its current format does not appear to be an appropriate method to achieve sufficient decontamination of NoV-contaminated raspberries. However, steam-ultrasound may be used to decontaminate smooth surface areas and utensils in food production and processing environments.

Development and evaluation of novel one-step TaqMan realtime RT-PCR assays for the detection and direct genotyping of genogroup I and II noroviruses

BACKGROUND

Current detection and genotyping methods of genogroup (G) I and II noroviruses (NoVs) consist of a 2-step approach including detection of viral RNA by TaqMan realtime RT-PCR (RT-qPCR) followed by conventional RT-PCR and sequencing of partial regions of ORF1 or ORF2.

OBJECTIVE

To develop novel long-template one-step TaqMan assays (L-RT-qPCR) for the rapid detection and direct genotyping of GI and GII NoVs and to evaluate the sensitivity and specificity of the assays.

STUDY DESIGN

GI and GII-specific broadly reactive L-RT-qPCR assays were developed by combining existing NoV primers and probes targeting the open reading frame (ORF)1-ORF2 junction as well as region C at the 5'-ORF2. The assays were validated using GI and GII RNA transcripts and a coded panel of 75 stool samples containing NoV strains representing 9 GI genotypes and 12 GII genotypes, as well as sapoviruses, astroviruses, polioviruses, and rotaviruses. L-RT-qPCR products were typed by sequencing.

RESULTS

The novel GI and GII L-RT-qPCR assays detected and typed all but one of the NoV positive panel samples. As few as 5-500 RNA copies could be accurately typed by sequencing of amplicons.

CONCLUSIONS

We developed novel one-step TaqMan RT-qPCR assays for the sensitive detection and direct genotyping of GI and GII NoVs from clinical and environmental matrices.

Comparison of methods for detection of norovirus in oysters

In the absence of culture methods for noroviruses, detection in foods relies on molecular techniques such as Reverse Transcription-Polymerase Chain Reaction (RT-PCR) on extracted viral RNA followed by PCR product confirmation by hybridisation and/or sequencing. However, in order to obtain a successful detection it is of great importance to remove the tissue inhibitors during the viral RNA extraction. To select the most efficient extraction procedure of oysters we have compared four protocols. A pool of digestive gland material from oyster samples was divided into 1.5 g portions and spiked with 10-fold dilutions of human faecal samples containing norovirus genogroup II. The samples were tested on three different occasions using four different sample treatment protocols. The protocols were assessed with regard to their ability to recover viral RNA and detect norovirus in spiked oysters and for their in-house reproducibility. One method using viral elution by a Mixer Mill Cell Disrupter resulted in a 10-fold better recovery than the other three protocols when an RT-seminested PCR (G2SKR/COG2F and G2SKR/G2SKF) detection approach was applied. Although less distinctive this was also the case when NoV was detected by a single round RT-PCR approach using the primers JV13i and JV12y. The second most efficient method was a method using chloroform extraction and polyethylene precipitation.

Comparison of methods and animal models commonly used for investigation of fecal microbiota: Effects of time, host and gender

Denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP) and plating on selective agars were used to study variation in the fecal microbiota of rats over time as well as variation between individuals. Investigated rats were either conventional and specific pathogen free (SPF), or human flora associated (HFA). A higher variation (p<0.05) in fecal microbiota over time was observed for HFA than for SPF animals. Analysis of DGGE and T-RFLP profiles of fecal microbiota from SPF and HFA rats revealed that variation over time was less significant than variation between individuals, and that phylogenetic profiles clustered according to gender. These observations should be taken into account when designing future research addressing changes in fecal microbiota.

Effects of Lactococcus lactis on composition of intestinal microbiota: role of nisin

This study examined the ability of (i) pure nisin, (ii) nisin-producing Lactococcus lactis strain CHCC5826, and (iii) the non-nisin-producing L. lactis strain CHCH2862 to affect the composition of the intestinal microbiota of human flora-associated rats. The presence of both the nisin-producing and the non-nisin-producing L. lactis strains significantly increased the number of Bifidobacterium cells in fecal samples during the first 8 days but decreased the number of enterococci/streptococci in duodenum, ileum, cecum, and colon samples as detected by selective cultivation. No significant changes in the rat fecal microbiota were observed after dosage with nisin. Pearson cluster analysis of denaturing gradient gel electrophoresis profiles of the 16S rRNA genes present in the fecal microbial population revealed that the microbiota of animals dosed with either of the two L. lactis strains were different from that of control animals dosed with saline. However, profiles of the microbiota from animals dosed with nisin did not differ from the controls. The concentrations of nisin estimated by competitive enzyme-linked immunosorbent assay (ELISA) were approximately 10-fold higher in the small intestine and 200-fold higher in feces than the corresponding concentrations estimated by a biological assay. This indicates that nisin was degraded or inactivated in the gastrointestinal tract, since fragments of this bacteriocin are detected by ELISA while an intact molecule is needed to retain biological activity.

Lactobacillus plantarum inhibits growth of Listeria monocytogenes in an in vitro continuous flow gut model, but promotes invasion of L. monocytogenes in the gut of gnotobiotic rats

The ability of the pediocin AcH producing Lactobacillus plantarum DDEN 11007 and its non-producing plasmid-cured isogenic variant, DDEN 12305 to prevent the persistence and growth of Listeria monocytogenes EP2 in two gastrointestinal (GI) tract models was examined. In vitro studies conducted in a two-stage continuous flow system showed that L. plantarum DDEN 11007 inhibited L. monocytogenes EP2 under these conditions, while less effect was seen of the non-bacteriocin producing variant. The inhibitory effect was more pronounced at pH 5 than at pH 7. No effect on persistence of L. monocytogenes in the GI tract was seen in gnotobiotic rats colonized with either the pediocin AcH producing or the non-bacteriocin producing variant of L. plantarum when compared to rats inoculated with L. monocytogenes EP2 alone. Surprisingly, inoculation of the gnotobiotic animals with either of the L. plantarum strains prior to inoculation with L. monocytogenes EP2 resulted in increased occurrence of L. monocytogenes in liver and spleen when compared to the animals inoculated with L. monocytogenes EP2 alone. Our results indicate that the presence of L. plantarum in the gut of gnotobiotes facilitates L. monocytogenes invasion by an unknown mechanism. This observation is however not necessarily specifically related to L. plantarum, and should not be interpreted as the expected effect in animals carrying a conventional intestinal microflora.

A model of hygiene practices and consumption patterns in the consumer phase

A mathematical model is presented, which addresses individual hygiene practices during food preparation and consumption patterns in private homes. Further, the model links food preparers and consumers based on their relationship to household types. For different age and gender groups, the model estimates (i) the probability of ingesting a meal where precautions have not been taken to avoid the transfer of microorganisms from raw food to final meal (a risk meal), exemplified by the event that the cutting board was not washed during food preparation, and (ii) the probability of ingesting a risk meal in a private home, where chicken was the prepared food item (a chicken risk meal). Chicken was included in the model, as chickens are believed to be the major source of human exposure to the foodborne pathogen Campylobacter. Monte Carlo simulations showed that the probability of ingesting a risk meal was highest for young males (aged 18-29 years) and lowest for the elderly above 60 years of age. Children aged 0-4 years had a higher probability of ingesting a risk meal than children aged 5-17 years. This difference between age and gender groups was ascribed to the variations in the hygiene levels of food preparers. By including the probability of ingesting a chicken meal at home, simulations revealed that all age groups, except the group above 60 years of age, had approximately the same probability of ingesting a chicken risk meal, the probability of females being slightly higher than that of males. The simulated results show that the probability of ingesting a chicken risk meal at home does not only depend on the hygiene practices of the persons preparing the food, but also on the consumption patterns of consumers, and the relationship between people preparing and ingesting food. This finding supports the need of including information on consumer behavior and preparation hygiene in the consumer phase of exposure assessments.

Quantitative risk assessment of human campylobacteriosis associated with thermophilic Campylobacter species in chickens

A quantitative risk assessment comprising the elements hazard identification, hazard characterization, exposure assessment, and risk characterization has been prepared to assess the effect of different mitigation strategies on the number of human cases in Denmark associated with thermophilic Campylobacter spp. in chickens. To estimate the human exposure to Campylobacter from a chicken meal and the number of human cases associated with this exposure, a mathematical risk model was developed. The model details the spread and transfer of Campylobacter in chickens from slaughter to consumption and the relationship between ingested dose and the probability of developing campylobacteriosis. Human exposure was estimated in two successive mathematical modules. Module 1 addresses changes in prevalence and numbers of Campylobacter on chicken carcasses throughout the processing steps of a slaughterhouse. Module 2 covers the transfer of Campylobacter during food handling in private kitchens. The age and sex of consumers were included in this module to introduce variable hygiene levels during food preparation and variable sizes and compositions of meals. Finally, the outcome of the exposure assessment modules was integrated with a Beta-Poisson dose-response model to provide a risk estimate. Simulations designed to predict the effect of different mitigation strategies showed that the incidence of campylobacteriosis associated with consumption of chicken meals could be reduced 30 times by introducing a 2 log reduction of the number of Campylobacter on the chicken carcasses. To obtain a similar reduction of the incidence, the flock prevalence should be reduced approximately 30 times or the kitchen hygiene improved approximately 30 times. Cross-contamination from positive to negative flocks during slaughter had almost no effect on the human Campylobacter incidence, which indicates that implementation of logistic slaughter will only have a minor influence on the risk. Finally, the simulations showed that people in the age of 18-29 years had the highest risk of developing campylobacteriosis.

In vitro and in vivo invasiveness of different pulsed-field gel electrophoresis types of Listeria monocytogenes

The virulence of different pulsed-field gel electrophoresis (PFGE) types of Listeria monocytogenes was examined by monitoring their ability to invade Caco-2 cells. Strains belonging to seven different PFGE types originating from both foods and humans were included. No significant differences in invasiveness were detected between strains isolated from humans and those isolated from food. Strains belonging to PFGE type 1 expressed a significantly lower ability to invade cells compared to strains belonging to other PFGE types. Although strains of PFGE type 2 also seemed to invade at a low level, this was not significant in the present study. PFGE types 1 and 2 as well as type 14 are more frequently found in food than the four other PFGE types examined and moreover have a relatively low prevalence in humans compared to their prevalence in food. Thus, the hypothesis that some PFGE types are less virulent than others is supported by this study showing that certain PFGE types of L. monocytogenes commonly found in food are less invasive than others to Caco-2 cells. In contrast to the differences in invasion, identical intracellular growth rates between the different PFGE types were observed. In vivo studies of the actual ability of the strains to invade the liver and spleen of cimetidine-treated rats following an oral dose of 10(9) L. monocytogenes cells were performed for isolates of PFGE types 1, 2, 5, and 15. After 2 days, equal amounts of bacteria were observed in the liver and spleen of the rats for any of the PFGE types tested.

Microbiological criteria for Listeria monocytogenes in foods under special consideration of risk assessment approaches

This paper shortly summarizes data related to risk assessment of Listeria monocytogenes. From available data on risk assessment, it is concluded that the levels of L. monocytogenes consumed is an important factor affecting the incidence of listeriosis. Foods that do not support the growth of L. monocytogenes are unlikely to be a source of listeriosis, whereas foods that support the growth to high levels, should be the target of risk management efforts. Based on current epidemiological information from several countries, a concentration of L. monocytogenes not exceeding 100/g of food at the time of consumption is of low risk to the consumers. In order not to exceed these levels at the point of consumption, lower levels may need to be applied at the port of entry, for those foods in which growth can occur within the shelf life. In order to establish such levels, knowledge of the shelf life and behaviour of L. monocytogenes in the food during prevailing storage and distribution conditions is needed.

Evaluation of a monoclonal antibody able to detect live Listeria monocytogenes and Listeria innocua

A monoclonal Listeria antibody, designated B4, was evaluated. The ability of the antibody to bind to viable bacteria belonging to Listeria spp. compared to bacteria of the same species killed by heat treatment, acid or base treatment, sanitizers, and irradiation was examined. The antibody was found to react with viable L. monocytogenes and L. innocua, but not with heat-killed (72 degrees C, 5 min) strains of these organisms. When L. monocytogenes and L. innocua were killed by methods other than heat treatment, it was ambiguous whether the antibody detected the organism or not. It was concluded that the B4 antibody has potential to be used in an immuno capture step to capture live L. monocytogenes and L. innocua from foods prior to identification of L. monocytogenes by polymerase chain reaction (PCR).

Variations in virulence between different electrophoretic types of Listeria monocytogenes

A total of 245 strains of Listeria monocytogenes, representing 33 different electrophoretic types (ETs), were examined quantitatively for haemolytic activity. No significant difference was observed in the mean haemolytic activity between different ETs. Eighty four out of 91 strains examined were found to be virulent for chick embryos. Strains belonging to ET 2 and ET 4 were found to be less virulent than strains of other ETs (P = 0.0447). Furthermore, strains from clinical cases were found to be more virulent (P = 0.0002) than strains from foods (the MTD among clinical strains was 2.46 in mean compared with 3.64 among food isolates). The explanation for this may be that more virulent strains are more prone to cause human infection. It is, however, also possible that strains of L. monocytogenes may become more virulent while multiplying in a living organism compared with multiplying in foods.

Incidence and control of Listeria monocytogenes in foods in Denmark

The Danish regulatory policy on Listeria monocytogenes in foods is based on the principles of HACCP and was developed using a health risk assessment approach. The Danish policy focuses examinations and criteria for L. monocytogenes in ready-to-eat foods and is based on a combination of inspection and product-testing. Based on current epidemiological information from several countries, a concentration of L. monocytogenes not exceeding 100 cfu/g of food at the time of consumption, seems to be of low risk to the consumers. In Denmark, ready-to-eat foods have been placed into six categories where absence of L. monocytogenes in 25 g is required in foods heat treated in the final package and in heat-treated as well as preserved, non heat-treated foods which can support growth within the shelf life. This level is necessary in foods capable of supporting growth, in order not to exceed 100 L. monocytogenes per g at the point of consumption. In heat-treated and preserved foods, which are not supportive of growth within the shelf-life and for raw, ready to eat foods, a level below 10 L. monocytogenes per g is regarded acceptable. A level between 10 and 100 L. monocytogenes per g is not satisfactory and a level above 100/g is not acceptable. Data on the qualitative and quantitative occurrence of L. monocytogenes in foods in Denmark are presented and discussed. In 1997 and 1998, greater than 15,000 samples from different categories of food were examined (semi-quantitatively) for the presence of L. monocytogenes. A significant difference could be seen in the number of samples containing more than 100 L. monocytogenes per g, between different categories of foods (1997, P = 0.001; 1998, P = 0.016). In 1997, preserved meat products and preserved fish products and to a lesser extent vegetables and meat or vegetable mayonnaise were more likely to contain high numbers (i.e. above 100 cfu/g) of L. monocytogenes than other food categories. In 1998, preserved meat products, but also heat-treated meat products, vegetables and meat or vegetable mayonnaise had the highest frequency of samples with > 100 L. monocytogenes per g. In a survey performed in 1994 and 1995, 1.3% of ready-to-eat food samples (heat-treated meat products, preserved meat and fish products) were found to be contaminated with L. monocytogenes at a level above 100 cfu/g. The samples included in this survey were primarily products produced by authorized companies and were comprised mainly of vacuum packed products or products packed in modified atmosphere and with long shelf lives, typically above several weeks. The corresponding percentages of positive samples primarily processed in the retail outlets (heat-treated meat products, preserved meat and fish products) in 1997 and 1998 were 0.3% and 0.6%, respectively. The results suggest that ready-to-eat meat and fish products with extended shelf-lives produced by authorized companies are more likely to contain high numbers (> 100 cfu/g) of L. monocytogenes than products processed in the retail sector which often have a shorter shelf life.

Multilocus enzyme electrophoresis for characterization of Listeria monocytogenes isolates: results of an international comparative study

Multilocus enzyme electrophoresis (MEE) is a standard technique that is used to elucidate the epidemiology of a variety of bacterial species. Recently, the method has been employed by several laboratories for investigations of clinical and foodborne isolates of Listeria monocytogenes. To assess the sensitivity and reproducibility of MEE in characterising L. monocytogenes isolates for epidemiological purposes and, ultimately, to agree on a standard protocol, seven laboratories participated in a blinded study of 80 strains. The strain collection included both epidemiologically related and unrelated isolates. Each laboratory used its own protocol for MEE. The number of enzymes that were assayed by the laboratories ranged from 8 to 23, and the total number of identified electrophoretic types (ETs) varied between 14 and 25. Of the II pairs of duplicate strains, the number of pairs recognised as identical by the seven laboratories ranged from 3 to 10 (median = 8). From 10 to 18 (median = 15) of the 22 groups of epidemiological related strains were recognised as homogeneous by the different laboratories. The discriminatory power of the method, calculated using Simpson's index of diversity for 69 strains (80 strains minus the 11 duplicates), ranged from 0.827 to 0.925. This relatively low discriminatory power is a consequence of a somewhat low genetic diversity of L. monocytogenes compared to other bacterial species. Efforts should be pursued to standardise the method in order to improve the intra- and inter-laboratory reproducibility.

Application of multilocus enzyme electrophoresis in studies of the epidemiology of Listeria monocytogenes in Denmark

A total of 245 strains of Listeria monocytogenes were investigated. These strains were isolated from human and animal cases of listeriosis as well as from different kinds of raw and processed foods. Thirty-three electrophoretic types (ETs) were identified among the 245 strains. The strains investigated included all human clinical strains isolated in Denmark during 1989 and 1990. Seventy-three percent of the strains isolated in this period were assigned to one of only two ETs (ET 1 and ET 4). ET 1, which was found to be the most frequently occurring ET among strains isolated from human clinical cases, was also found to occur rather frequently in animal clinical cases. ET 1 was, however, found only sporadically among strains isolated from foods and food factories. The data indicate that there might be something distinctive about the physiology or ecology of the ET 1 clone which makes it more likely to bring about disease in human beings either because of high pathogenicity or because of a special ability to multiply to infectious doses in processed foods. Another type, designated ET 4, was found to be the next most frequently occurring ET, after ET 1, among human clinical isolates. This could be explained by the fact that ET 4 was found to be the most frequently occurring ET within food isolates.

Comparison of multilocus enzyme electrophoresis (MEE), ribotyping, restriction enzyme analysis (REA) and phage typing for typing of Listeria monocytogenes

The discriminatory power of four methods for typing of Listeria monocytogenes was compared. The four methods were multilocus enzyme electrophoresis (MEE), ribotyping, restriction enzyme analysis (REA), and a newly developed Danish phage typing system. Ninety-nine human clinical, food and slaughterhouse isolates of Listeria monocytogenes were typed by each method. The most discriminatory single typing method was phage typing with an overall discriminatory index (DI) of 0.88 followed by REA, MEE and ribotyping with DI-values at 0.87, 0.83 and 0.79 respectively. Considering strains from each of the two predominant O-serotypes alone, serotype 1 was best discriminated by the molecular typing methods, in particular REA, which showed a DI of 0.92. The serotype 4 strains were best discriminated by phage typing (DI = 0.78). If two or more typing methods were combined, the combination of REA and MEE were found to be the most discriminatory combination. The DI values were 0.96, 0.74 and 0.90 for serotype 1, 4, and both combined, respectively. Phage typing is a rapid and inexpensive typing method but not as reproducible as the molecular typing methods. It is the most suitable method for mass screening. In situations where results are required to be highly reliable, i.e. when studying the relationships between only a few strains, a single or a combination of molecular typing methods should be used, preferable MEE and REA.

Characterisation of Danish isolates of Listeria monocytogenes by multilocus enzyme electrophoresis

A total of 84 strains of Listeria monocytogenes were analysed by multilocus enzyme electrophoresis at twelve enzyme loci. Eight enzyme loci were polymorphic with between 2 and 4 alleles per locus. Fourteen electrophoretic types (ETs) were identified. Among 62 human clinical isolates from Denmark, 8 different ETs were defined. Two ETs, designated ET 1 and ET 6, accounted for 77% of the human clinical isolates investigated. These ETs are identical with those responsible for several epidemics in Switzerland and in the United States. Comparison of 58 isolates of L. monocytogenes, typed by MEE, in relation to phage typing showed that phage typing was more discriminatory than MEE. The ability of MEE to distinguish between phage types of Epi-type and other phage types, however, was almost optimal. MEE typed 23 of 24 strains of Epi-type as belonging to ET 1. In contrast ET 1 was not found in 26 strains with phage types other than the Epi-type.

The incidence of Listeria spp. in faeces of Danish pigs and in minced pork meat

One hundred and seventy-two samples of pig faeces, collected at a slaughterhouse, were investigated for Listeria species. Three of the samples (1.7%) contained L. monocytogenes, while L. innocua was demonstrated in four other samples. The 172 samples represented pigs from 72 herds, 14 (19%) of which were SPF herds. Listeria was not demonstrated in any of the samples from the SPF herds representing 24% of all samples investigated. This indicates that the incidence of L. monocytogenes in SPF herds might be very low. In 51 samples of minced pork, Listeria spp. were demonstrated in 32 samples, L. monocytogenes in six samples, L. innocua in 26 samples, and L. seeligeri in one sample. In comparison with similar findings in cattle faeces and minced beef, the conclusion was drawn that faecal contamination may play an important rôle in the dissemination of L. monocytogenes in raw meats.