The recent finding that the formation of staphylococcal enterotoxins in food is very different from that in cultures of pure Staphylococcus aureus sheds new light on, and brings into question, ...traditional microbial risk assessment methods based on planktonic liquid cultures. In fact, most bacteria in food appear to be associated with surfaces or tissues in various ways, and interaction with other bacteria through molecular signaling is prevalent. Nowadays it is well established that there are significant differences in the behavior of bacteria in the planktonic state and immobilized bacteria found in multicellular communities. Thus, in order to improve the production of high-quality, microbiologically safe food for human consumption, in situ data on enterotoxin formation in food environments are required to complement existing knowledge on the growth and survivability of S. aureus. This review focuses on enterotoxigenic S. aureus and describes recent findings related to enterotoxin formation in food environments, and ways in which risk assessment can take into account virulence behavior. An improved understanding of how environmental factors affect the expression of enterotoxins in foods will enable us to formulate new strategies for improved food safety.
The qualified presumption of safety (QPS) was developed to provide a safety pre‐assessment within EFSA for microorganisms. Strains belonging to QPS taxonomic units (TUs) still require an assessment ...based on a specific data package, but QPS status facilitates fast track evaluation. QPS TUs are unambiguously defined biological agents assessed for the body of knowledge, their safety and their end use. Safety concerns are, where possible, to be confirmed at strain or product level, and reflected as ‘qualifications’. Qualifications need to be evaluated at strain level by the respective EFSA units. The lowest QPS TU is the species level for bacteria, yeasts and protists/algae, and the family for viruses. The QPS concept is also applicable to genetically modified microorganisms used for production purposes if the recipient strain qualifies for the QPS status, and if the genetic modification does not indicate a concern. Based on the actual body of knowledge and/or an ambiguous taxonomic position, the following TUs were excluded from the QPS assessment: filamentous fungi, oomycetes, streptomycetes, Enterococcus faecium, Escherichia coli and bacteriophages. The list of QPS‐recommended biological agents was reviewed and updated in the current opinion and therefore now becomes the valid list. For this update, reports on the safety of previously assessed microorganisms, including bacteria, yeasts and viruses (the latter only when used for plant protection purposes) were reviewed, following an Extensive Literature Search strategy. All TUs previously recommended for 2016 QPS list had their status reconfirmed as well as their qualifications. The TUs related to the new notifications received since the 2016 QPS opinion was periodically evaluated for QPS status in the Statements of the BIOHAZ Panel, and the QPS list was also periodically updated. In total, 14 new TUs received a QPS status between 2017 and 2019: three yeasts, eight bacteria and three algae/protists.
Campylobacter is a major bacterial cause of infectious diarrheal illness in Sweden and in many other countries. Handling and consumption of chicken has been identified as important risk factors. The ...purpose of the present study was to use data from a national baseline study of thermophilic
Campylobacter spp. in raw Swedish broiler chickens in order to evaluate some risk management strategies and the frequency of consumer mishandling, i.e., handling leading to possible cross-contamination. A probabilistic model describing variability but not uncertainty was developed in Excel and @Risk. The output of the model was the probability of illness per handling if the chicken was mishandled. Uncertainty was evaluated by performing repeated simulations and substituting model parameters, distributions and software (Analytica). The effect of uncertainty was within a factor of 3.2 compared to the baseline scenario. For
Campylobacter spp. prevalence but not concentration, there was a one-to-one relation with risk. The effect of a 100-fold reduction in the levels of
Campylobacter spp. on raw chicken reduced the risk by a factor of 12 (fresh chicken) to 30 (frozen chicken). Highly-contaminated carcasses contributed most to risk and it was estimated that by limiting the contamination to less than 4 log CFU per carcass, the risk would be reduced to less than 17% of the baseline scenario. Diverting all positive flocks to freezing was estimated to result in 43% as many cases as the baseline. The second best diversion option (54% of baseline cases) was to direct all chickens from the two worst groups of producers, in terms of percentages of positive flocks delivered, to freezing. The improvement of using diverting was estimated to correspond to between 5 to 767 fewer reported cases for the different strategies depending on the assumptions of the proportion of reported cases (1 to 50%) caused by
Campylobacter spp. from Swedish chicken. The estimated proportion of consumer mishandlings sufficient to explain 1 to 50% of the reported campylobacteriosis cases was 0.005–0.25%, or taking estimated underreporting into consideration, was 0.05–2.6%. The strategy of using a diversion treatment, e.g., freezing, based on the past performance of producers was promising, but needs to be evaluated further. Although challenging, consumer education has a great potential given the direct relation between behaviour and risk. However, any improvements following implementation of these strategies may be hard to detect if less than 50% of reported cases are exposed via chicken and the cross-contamination route.
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.
This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2018.EN-1352/full
The provisional molecular approach, proposed by EFSA in 2013, for the pathogenicity assessment of Shiga toxin‐producing Escherichia coli (STEC) has been reviewed. Analysis of the confirmed reported ...human STEC infections in the EU/EEA (2012–2017) demonstrated that isolates positive for any of the reported Shiga toxin (Stx) subtypes (and encoding stx gene subtypes) may be associated with severe illness (defined as bloody diarrhoea (BD), haemolytic uraemic syndrome (HUS) and/or hospitalisation). Although strains positive for stx2a gene showed the highest rates, strains with all other stx subtypes, or combinations thereof, were also associated with at least one human case with a severe clinical outcome. Serogroup cannot be used as a predictor of clinical outcome and the presence of the intimin gene (eae) is not essential for severe illness. These findings are supported by the published literature, a review of which suggested there was no single or combination of virulence markers associated exclusively with severe illness. Based on available evidence, it was concluded that all STEC strains are pathogenic in humans, capable of causing at least diarrhoea and that all STEC subtypes may be associated with severe illness. Source attribution analysis, based on ‘strong evidence’ outbreak data in the EU/EEA (2012–2017), suggests that ‘bovine meat and products thereof’, ‘milk and dairy products’, ‘tap water including well water’ and ‘vegetables, fruit and products thereof’ are the main sources of STEC infections in the EU/EEA, but a ranking between these categories cannot be made as the data are insufficient. Other food commodities are also potentially associated with STEC infections but rank lower. Data gaps are identified, and are primarily caused by the lack of harmonisation in sampling strategies, sampling methods, detection and characterisation methods, data collation and reporting within the EU.
The role of food‐producing environments in the emergence and spread of antimicrobial resistance (AMR) in EU plant‐based food production, terrestrial animals (poultry, cattle and pigs) and aquaculture ...was assessed. Among the various sources and transmission routes identified, fertilisers of faecal origin, irrigation and surface water for plant‐based food and water for aquaculture were considered of major importance. For terrestrial animal production, potential sources consist of feed, humans, water, air/dust, soil, wildlife, rodents, arthropods and equipment. Among those, evidence was found for introduction with feed and humans, for the other sources, the importance could not be assessed. Several ARB of highest priority for public health, such as carbapenem or extended‐spectrum cephalosporin and/or fluoroquinolone‐resistant Enterobacterales (including Salmonella enterica), fluoroquinolone‐resistant Campylobacter spp., methicillin‐resistant Staphylococcus aureus and glycopeptide‐resistant Enterococcus faecium and E. faecalis were identified. Among highest priority ARGs blaCTX‐M, blaVIM, blaNDM, blaOXA‐48-like, blaOXA‐23, mcr, armA, vanA, cfr and optrA were reported. These highest priority bacteria and genes were identified in different sources, at primary and post‐harvest level, particularly faeces/manure, soil and water. For all sectors, reducing the occurrence of faecal microbial contamination of fertilisers, water, feed and the production environment and minimising persistence/recycling of ARB within animal production facilities is a priority. Proper implementation of good hygiene practices, biosecurity and food safety management systems is very important. Potential AMR‐specific interventions are in the early stages of development. Many data gaps relating to sources and relevance of transmission routes, diversity of ARB and ARGs, effectiveness of mitigation measures were identified. Representative epidemiological and attribution studies on AMR and its effective control in food production environments at EU level, linked to One Health and environmental initiatives, are urgently required.
The primary objective of this study was to characterise (microbiology and physical parameters) beef carcasses and primals during chilled storage. A minor aim was to compare observed growth of key ...spoilage bacteria on carcasses with that predicted by ComBase and the Food Safety Spoilage Predictor (FSSP). Total viable count (TVC), total Enterobacteriacae count (TEC), Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and Clostridium spp. were monitored on beef carcasses (n = 30) and primals (n = 105) during chilled storage using EC Decision 2001/471/EC and ISO sampling/laboratory procedures. The surface and/or core temperature, pH and water activity (aw) were also recorded. Clostridium (1.89 log10 cfu/cm2) and Pseudomonas spp. (2.12 log10 cfu/cm2) were initially the most prevalent bacteria on carcasses and primals, respectively. The shortest mean generation time (G) was observed on carcasses with Br. thermosphacta (20.3 h) and on primals with LAB (G = 68.8 h) and Clostridium spp. (G = 67 h). Over the course of the experiment the surface temperature decreased from 37 °C to 0 °C, pH from 7.07 to 5.65 and aw from 0.97 to 0.93 The observed Pseudomonas spp. and Br. thermosphacta growth was more or less within the range of predictions of Combase. In contrast, the FSSP completely overestimated the growth of LAB. This study contributes to the very limited microbiological data on beef carcasses and primals during chilling.
•Pseudomonas concentrations on beef primals at packaging increased during 6 weeks vacuum packaged storage.•Brochothrix thermosphacta grew faster than lactic acid bacteria on vacuum packaged beef primals.•Combase may be used to predict Pseudomonas spp. and Br. thermosphacta growth on beef carcasses.
Qualified presumption of safety (QPS) was developed to provide a generic safety evaluation for biological agents to support EFSA's Scientific Panels. The taxonomic identity, body of knowledge, safety ...concerns and antimicrobial resistance are assessed. Safety concerns identified for a taxonomic unit (TU) are where possible to be confirmed at strain or product level, reflected by ‘qualifications’. No new information was found that would change the previously recommended QPS TUs and their qualifications. The list of microorganisms notified to EFSA was updated with 54 biological agents, received between April and September 2019; 23 already had QPS status, 14 were excluded from the QPS exercise (7 filamentous fungi, 6 Escherichia coli, Sphingomonas paucimobilis which was already evaluated). Seventeen, corresponding to 16 TUs, were evaluated for possible QPS status, fourteen of these for the first time, and Protaminobacter rubrum, evaluated previously, was excluded because it is not a valid species. Eight TUs are recommended for QPS status. Lactobacillus parafarraginis and Zygosaccharomyces rouxii are recommended to be included in the QPS list. Parageobacillus thermoglucosidasius and Paenibacillus illinoisensis can be recommended for the QPS list with the qualification ‘for production purposes only’ and absence of toxigenic potential. Bacillus velezensis can be recommended for the QPS list with the qualifications; the absence of toxigenic potential and the absence of aminoglycoside production, including the genes encoding this. Cupriavidus necator, Aurantiochytrium limacinum and Tetraselmis chuii can be recommended for the QPS list with the qualification; for production purposes only. Pantoea ananatis is not recommended for the QPS list due to lack of body of knowledge in relation to its pathogenicity potential for plants. Corynebacterium stationis, Hamamotoa singularis, Rhodococcus aetherivorans and Rhodococcus ruber cannot be recommended for the QPS list due to lack of body of knowledge. Kodamaea ohmeri cannot be recommended for the QPS list due to safety concerns.
The potential of Staphylococcus aureus cheese isolates to grow and produce staphylococcal enterotoxin A under conditions typical for cheese making was investigated in three broth experiments. The ...effect of the concentration of undissociated lactic acid (HLac) in conjunction with specific pH values was studied by adjusting pH at a single concentration of lactic acid. First, the time-to-growth of S. aureus was modelled by using survival analysis and absorbance data obtained from an automated turbidity reader. The fitted model describes the time to growth and indicates the growth ⁄ no growth boundary of S. aureus as a function of HLac concentration, temperature and water activity. Second, growth rates and lag times of S. aureus were estimated after two different pre-treatments in skim milk at three HLac concentrations and two temperatures based on optical detection times of serial dilutions of bacterial solutions. Growth rates differed between strains, and increased with increasing temperature and decreasing HLac concentration. Preliminary results indicate that lag times were dependent on pre-treatment suggesting that the growth potential of S. aureus in cheese curd may be greater if milk is used immediately after milking compared to holding at 4°C after milking. Third, growth, inactivation, and enterotoxin A production of S. aureus strains were investigated at twelve combinations of HLac concentration and temperature. Concentrations of enterotoxin A increased linearly during the first four days, with a production rate increasing with increasing temperature and decreasing HLac concentration. Significant amounts of enterotoxin A were produced during extended incubation, up to 14days, but then initial pH had changed. This highlights a potential limitation of modelling based on the initial environmental conditions in batch experiments.
In summary, ranges of time-to-growth, growth rates, lag times and enterotoxin A production rates of S. aureus in the presence of HLac were estimated. The results can be used together with process data to indicate the range and magnitude of growth and enterotoxin A production during initial stages of cheese production.
► A time-to-growth model for S. aureus as a function of HLac, T and aw is described. ► Lag time of S. aureus may decrease in curd if milk is used directly after milking. ► SEA was detected when S. aureus levels exceeded 6.8log10CFUml−1. ► Initial SEA production rates increased linearly with temperature and decreasing HLac. ► Considerable amounts of SEA were produced after two weeks of incubation.
An increase in confirmed human salmonellosis cases in the EU after 2014 triggered investigation of contributory factors and control options in poultry production. Reconsideration of the five current ...target serovars for breeding hens showed that there is justification for retaining Salmonella Enteritidis, Salmonella Typhimurium (including monophasic variants) and Salmonella Infantis, while Salmonella Virchow and Salmonella Hadar could be replaced by Salmonella Kentucky and either Salmonella Heidelberg, Salmonella Thompson or a variable serovar in national prevalence targets. However, a target that incorporates all serovars is expected to be more effective as the most relevant serovars in breeding flocks vary between Member State (MS) and over time. Achievement of a 1% target for the current target serovars in laying hen flocks is estimated to be reduced by 254,400 CrI9598,540; 602,700 compared to the situation in 2016. This translates to a reduction of 53.4% CrI9539.1; 65.7 considering the layer‐associated human salmonellosis true cases and 6.2% considering the overall human salmonellosis true cases in the 23 MSs included in attribution modelling. A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non‐cage compared to cage systems. A conclusion on the effect of outdoor access or impact of the shift from conventional to enriched cages could not be reached. A similar review for broiler chickens concluded that the evidence that outdoor access affects the occurrence of Salmonella is inconclusive. There is conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flocks. Based on scientific evidence, an impact of Salmonella control programmes, apart from general hygiene procedures, on the prevalence of Campylobacter in broiler flocks at the holding and on broiler meat at the end of the slaughter process is not expected.
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