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Biesta-Peters E.G.,Laboratory for Food and Feed Safety | Dissel S.,Laboratory for Food and Feed Safety | Reij M.W.,Wageningen University | Zwietering M.H.,Wageningen University | In't Veld P.H.,Netherlands Food and Consumer Product Safety Authority
Journal of Food Protection

The emetic toxin cereulide, which can be produced by Bacillus cereus, can be the cause of food poisoning upon ingestion by the consumer. The toxin causes vomiting and is mainly produced in farinaceous food products. This article includes the prevalence of B. cereus and of cereulide in food products in The Netherlands, a characterization of B. cereus isolates obtained, cereulide production conditions, and a comparison of consumer exposure estimates with those of a previous exposure assessment. Food samples (n=1,489) were tested for the presence of B. cereus; 5.4% of the samples contained detectable levels (>102 CFU/ g), and 0.7% contained levels above 105 CFU/g. Samples (n=3,008) also were tested for the presence of cereulide. Two samples (0.067%) contained detectable levels of cereulide at 3.2 and 5.4 μg/kg of food product. Of the 481 tested isolates, 81 produced cereulide and/or contained the ces gene. None of the starch-positive and hbl-containing isolates possessed the ces gene, whereas all strains contained the nhe genes. Culture of emetic B. cereus under nonoptimal conditions revealed a delay in onset of cereulide production compared with culture under optimal conditions, and cereulide was produced in all cases when B. cereus cells had been in the stationary phase for some time. The prevalence of cereulide-contaminated food approached the prevalence of contaminated products estimated in an exposure assessment. The main food safety focus associated with this pathogen should be to prevent germination and growth of any B. cereus present in food products and thus prevent cereulide production in foods. Copyright ©, International Association for Food Protection. Source

Sprong R.C.,National Institute for Public Health and Environment RIVM | De Wit-Bos L.,National Institute for Public Health and Environment RIVM | Zeilmaker M.J.,National Institute for Public Health and Environment RIVM | Alewijn M.,RIKILT Wageningen UR | And 2 more authors.
World Mycotoxin Journal

A mycotoxin-dedicated total diet study (mTDS) allowing assessment of occurrence and dietary exposure to these substances was developed and carried out in the Netherlands in 2013. First, literature was searched to establish the occurrence profile of mycotoxins. Next, foods as consumed according to the Dutch National Food Consumption Surveys (DNFCS) for young children and persons aged 7-69 years, categorised in several food categories, were ranked according to their summed consumption. Subsequently, foods with the highest consumptions were included to cover >85% of the consumption of a particular food category. In some cases, foods other than those contributing to the upper 85% consumption within a food category were included based on their expected high mycotoxin contamination. In some other cases, foods not contributing to mycotoxin exposure were excluded. This resulted in 130 foods to be included in this mTDS. Since a sample size of 12 was established per food, 1,560 food items were purchased for the population aged 7-69 years. Fifty seven additional food items were purchased to take into account the different consumption profile of young children. The 1,617 food items were prepared as consumed based on information available in the food consumption surveys. The prepared food items were combined according to the different consumption forms of the 130 selected foods (e.g. fresh, canned or frozen). This resulted in 213 subsamples, which were proportionally to their consumption further pooled into 88 composite samples. These composite samples covered 87 and 88% of the amount foods consumed by young children and the population aged 7-69 years, respectively. This design allows analysis of mycotoxin occurrence and the subsequent exposure assessment using aggregated food categories reflected by the 88 composite samples, as well as a more refined approach by analysing 213 subsamples. © 2015 Wageningen Academic Publishers. Source

Hordijk J.,University Utrecht | Hordijk J.,Central Veterinary Institute | Wagenaar J.A.,University Utrecht | Wagenaar J.A.,Central Veterinary Institute | And 7 more authors.

Objectives:The presence of ESBL/AmpC-producing E. coli in cattle has been reported previously, however information on veal calves is limited. This study describes the prevalence and molecular characteristics of E. coli with non-wild type susceptibility to cefotaxime in veal calves at slaughter.Methods:Faecal samples from 100 herds, 10 individual animals per herd, were screened for E. coli with non-wild type susceptibility for cefotaxime. Molecular characterization of ESBL/AmpC genes and plasmids was performed on one isolate per herd by microarray, PCR and sequence analysis.Results:66% of the herds were positive for E. coli with non-wild type susceptibility for cefotaxime. Within-herd prevalence varied from zero to 90%. 83% of E. coli producing ESBL/AmpC carried blaCTX-M genes, of which blaCTX-M-1, blaCTX-M-14 and blaCTX-M-15 were most prevalent. The dominant plasmids were IncI1 and IncF-type plasmids.Conclusions:A relatively high prevalence of various blaCTX-M producing E. coli was found in veal calves at slaughter. The genes were mainly located on IncI1 and IncF plasmids. © 2013 Hordijk et al. Source

Copini P.,Wageningen University | Sass-Klaassen U.,Wageningen University | den Ouden J.,Wageningen University | Mohren G.M.J.,Wageningen University | Loomans A.J.M.,Netherlands Food and Consumer Product Safety Authority
Trees - Structure and Function

To control invasive Anoplophora outbreaks, it is crucial to accurately date infestation dynamics. Dating of Anoplophora outbreaks is possible as these xylobiont insects induce wounds in living trees by forming e.g., exit holes. This study investigates to what precision these wounds can be dated with dendrochronological techniques. In an experimental setting, we studied the precision of wound dating on Acer palmatum, an ornamental tree occasionally containing larvae of A. chinensis. We studied the development of wound reactions at the beginning, during and after the growing season, both in relation to leaf phenology and intra-annual tree-ring growth. We found that the precision of dating exit holes is limited due to the highly variable intra-annual tree-ring growth whereby only an accurate distinction can be made between wounds originated during, or after tree-ring formation. The resolution was improved using local growth-the local reactivation of xylem growth around the wound-as a marker for wounds that occurred at the end of the growing season. We conclude that the intra-annual precision of dating Anoplophora outbreaks in Acer palmatum in the temperate North-western European climate is limited to three distinct phases: (i) The period of dormancy and leaf emergence (ca. October until April/beginning of May), when the wounds are located at the tree-ring boundary (ii) The period of tree-ring growth in which wounds are located within the tree ring (ca. end of April/beginning of May until late August/beginning of September), (iii) end of growing season (ca. end of August/September) in which local growth occurs. © 2013 Springer-Verlag Berlin Heidelberg. Source

Maurice H.,Netherlands Food and Consumer Product Safety Authority | Thulke H.-H.,Helmholtz Center for Environmental Research | Schmid J.S.,Helmholtz Center for Environmental Research | Schmid J.S.,University of Applied Sciences of Leipzig | And 2 more authors.
Preventive Veterinary Medicine

Although generally considered a rodent virus, pigs sometimes were suggested a potential reservoir host for encephalomyocarditis virus (EMCV), implying pig-to-pig transmission can cause major outbreaks in a pig population (basic reproduction ratio, R0 > 1). An earlier experimental study on EMCV transmission among pigs was inconclusive in this respect (R0 ≈ 1.24; CI 0.4-4.4). In this study we used a simulation model to extrapolate the experimental results to commercial, compartmentalised pig housings and tested to what extend contacts between pigs in different pens needed to be reduced in order to prevent major outbreaks in a compartment following a single introduction. The final size of simulated outbreaks was measured and the probability to observe outbreaks that affected at least 50 or 80% of the pens was calculated. Simulation scenarios compare one homogeneously mixing compartment (no fence) to epidemiological theory and an increasing effect of fencing on the pig-to-pig transmission between pigs in neighbouring pens. For any R0 < 1.24 the probability to observe outbreaks affecting more than 50% of the pens remained below 10% if compartmentalisation was introduced leaving per capita transmission rate unchanged. If fences also reduced contact transmission the probability to observe major outbreaks was below 50% for any R0 < 2.7. Only for R0 > 4, major outbreaks occurred with more than 50% chance even if only minimal contact between adjacent pens was allowed. In conclusion the results suggested that in a compartmentalised pig housing one single EMCV introduction is unlikely to cause a major outbreak by direct pig-to-pig transmission alone. Other mechanisms e.g. multiple introductions from a rodent reservoir may be required for large outbreaks to occur. © 2016 Elsevier B.V. Source

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