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See detailDiversity, phylogenetic relationship and antibacterial potential of Bifidobacterium species isolated from raw milk production chain in Abidjan (Côte d'Ivoire)
Kouamé-Sina, Sylvie Mireille; Dadié, Adjéhi; Makita, Kohei et al

in African Journal of Microbiology Research [=AJMR] (2011), 5(21), 3394-3403

The local dairy commodity, from farm to retail point, is informal and often escapes safety surveillance and results in high contamination of local milk by pathogens. The objective of this study was to ... [more ▼]

The local dairy commodity, from farm to retail point, is informal and often escapes safety surveillance and results in high contamination of local milk by pathogens. The objective of this study was to determine the biodiversity of Bifidobacterium species in the informal dairy production chain in Abidjan and evaluate their potential antibacterial activity against pathogens. Bifidobacterium species were identified after sequencing of hsp60 genes. Results showed that Bifidobacterium were present in 9% of samples. Milkers' hands (14%) and cows’s udders (14%) were the most contaminated with Bifidobacterium. These isolates belong to five different species. Most Bifidobacterium isolated are Bifidobacterium minimum (53%) and Bifidobacterium pseudolongum subsp. Globosum (24.4%). The other strains are composed of one strain of Bifidobacterium thermophilum, Bifidobacterium thermacidophilum subsp. suis and Bifidobacterium magnum. The isolated Bifidobacterium species have antibacterial activities that are not related to bacteriocins production, but to organic acids production (65%), which exert in vitro inhibitory action against Listeria monocytogenes, Salmonella hadar and Salmonella typhimurium, Staphylococcus aureus, Escherichia coli O27 and Escherichia coli O157H7. However, ensuring milk safety along the local milk production chain requires implementation of good hygiene practices together with adapted technology, such as fermentation. [less ▲]

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See detailBifidobacterium pseudolongum are efficient indicators of animal fecal contamination in raw milk cheese industry
Delcenserie, Véronique ULg; Gavini, Françoise; China, Bernard et al

in BMC Microbiology (2011), 11(178),

Background: The contamination of raw milk cheeses (St-Marcellin and Brie) from two plants in France was studied at several steps of production (raw milk, after addition of rennet - St-Marcellin - or after ... [more ▼]

Background: The contamination of raw milk cheeses (St-Marcellin and Brie) from two plants in France was studied at several steps of production (raw milk, after addition of rennet - St-Marcellin - or after second maturation - Brie -, after removal from the mold and during ripening) using bifidobacteria as indicators of fecal contamination. Results: Bifidobacterium semi-quantitative counts were compared using PCR-RFLP and real-time PCR. B. pseudolongum were detected in 77% (PCR-RFLP; 1.75 to 2.29 log cfu ml-1) at the different production steps) and 68% (real-time PCR; 2.19 to 2.73 log cfu ml-1) of St-Marcellin samples and in 87% (PCR-RFLP; 1.17 to 2.40 log cfu ml-1) of Brie cheeses samples. Mean counts of B. pseudolongum remained stable along both processes. Two other populations of bifidobacteria were detected during the ripening stage of St-Marcellin, respectively in 61% and 18% of the samples (PCR-RFLP). The presence of these populations explains the increase in total bifidobacteria observed during ripening. Further characterization of these populations is currently under process. Forty-eight percents (St-Marcellin) and 70 % (Brie) of the samples were B. pseudolongum positive / E. coli negative while only 10 % (St-Marcellin) and 3 % (Brie) were B. pseudolongum negative / E. coli positive. Conclusions: The increase of total bifidobacteria during ripening in Marcellin’s process does not allow their use as fecal indicator. The presence of B. pseudolongum along the processes defined a contamination from animal origin since this species is predominant in cow dung and has never been isolated in human feces. B. pseudolongum was more sensitive as an indicator than E. coli along the two different cheese processes. B. pseudolongum should be used as fecal indicator rather than E. coli to assess the quality of raw milk and raw milk cheeses. Results: Bifidobacterium semi-quantitative counts were compared using PCR-RFLP and real-time PCR. Bif. pseudolongum were detected in 77% (PCR-RFLP; 1.75 to 2.29 log cfu ml-1) at the different production steps) and 68% (real-time PCR; 2.19 to 2.73 log cfu ml-1) of St-Marcellin samples and in 87% (PCR-RFLP; 1.17 to 2. 40 log cfu ml-1) of Brie cheeses samples. Mean counts of Bif. pseudolongum remained stable along both processes. Two other populations of bifidobacteria were detected during the ripening stage of St-Marcellin, respectively in 61% and 18% of the samples (PCR-RFLP). The presence of these populations explains the increase in total bifidobacteria observed during ripening. Further identification of these species is currently under process. Forty-eight percents (St-Marcellin) and 70 % (Brie) of the samples were Bif. pseudolongum positive / E. coli negative while only 10 % (St-Marcellin) and 3 % (Brie) were Bif. pseudolongum negative / E. coli positive. Conclusions: The increase of total bifidobacteria during ripening in Marcellin’s process does not allow their use as fecal indicator. The presence of Bif. pseudolongum along the processes defined a contamination from animal origin since this species is predominant in cow dung and has never been isolated in human feces. Bif. pseudolongum was more sensitive as an indicator than E. coli along the two different cheese processes. Bif. pseudolongum should be used as fecal indicator rather than E. coli to assess the quality of raw milk and raw milk cheeses. [less ▲]

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See detailChilling of heavy carcasses from double muscled cattle: time-temperature evolution and predictive modelling of growth of Listeria monocytogenes and Clostridium perfringens
Delhalle, Laurent ULg; Collignon, Bertrand; Dehard, Sandrine ULg et al

Poster (2010, August)

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from ... [more ▼]

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from the Belgian Blue breed. Three slaughterhouses were selected for temperature and pH measurements during the chilling process at 6 different days on 4 half carcasses in order to obtain representative data from heavy carcasses with high muscular development. Predictive microbiology was used to evaluate the potential growth of Listeria monocytogenes and Clostridium perfringens on the surface and in the depth of the carcasses. The gamma concept was chosen as secondary model taking into account the effect of temperature, pH and water activity on the selected bacteria during the chilling process. The predicted growth potential of Listeria monocytogenes is influenced by the different environmental conditions of the selected slaughterhouses and could reach 1.4 log CFU/cm² after the chilling process. The potential growth of Clostridium perfringens is limited due to unfavourable conditions during the first hours and to low temperature later. It can be concluded that when the initial level of contaminating bacteria is not excessive the speed at which the carcass is currently chilled is sufficient to limit the growth of these two pathogens and to ensure the product quality [less ▲]

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See detailLa microbiologie prévisionnelle : un nouvel outil de maîtrise de la qualité microbiologique des denrées alimentaires
Delhalle, Laurent ULg; Clinquart, Antoine ULg; Daube, Georges ULg

in Food Science and Law (2010), 2

Les nouveaux outils de microbiologie prévisionnelle permettent de mieux comprendre et de maîtriser le comportement des micro-organismes dans la chaîne alimentaire. La législation européenne récente, dont ... [more ▼]

Les nouveaux outils de microbiologie prévisionnelle permettent de mieux comprendre et de maîtriser le comportement des micro-organismes dans la chaîne alimentaire. La législation européenne récente, dont le but est garantir un niveau élevé de sécurité sanitaire des aliments proposés au consommateur, mentionne cette méthodologie comme outil de référence. Les autorités en charge de la gestion de la santé publique et les industriels ont maintenant à leur disposition des outils leur permettant de comprendre les flux de contamination dans la chaîne alimentaire, de fixer une date limite de consommation, d’optimaliser les processus de transformation et de conservation, et de proposer des aliments sûrs aux consommateurs. Cette discipline offre la possibilité, à travers ses modèles et ses concepts, d’exploiter des données issues d’expérimentations réalisées au laboratoire ou en production et de les convertir en applications qui permettent d’évaluer la stabilité et la sécurité d’une denrée alimentaire. [less ▲]

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See detailModeling Microbial Cross-contamination in Quick Service Restaurants by Means of Experimental Simulations With Bacillus Spores
Baptista Rodrigues, Ana Lúcia ULg; Crevecoeur, Sébastien ULg; Dure, Remi et al

Poster (2010)

Cross contamination has been frequently mentioned as being in the origin of a wide range of food borne outbreaks. Handling of food is one of the ways through which cross contamination may occur. For many ... [more ▼]

Cross contamination has been frequently mentioned as being in the origin of a wide range of food borne outbreaks. Handling of food is one of the ways through which cross contamination may occur. For many different reasons, quick service restaurants are particularly at risk. Due to its importance, cross contamination via the hands should be taken into consideration when carrying out a quantitative risk assessment. The main goal of this study was to determine transfer rates of bacteria to and via the hands, reduction rates of two hand sanitizing procedures and to apply the results to a quantitative microbial risk assessment model. According to our results, handling of a portion of raw minced meat contaminated at 4.104 cfu leads to the presence of 24 cfu on both hands, 3 cfu on ready-to-eat product (RTE) manipulated with unwashed hands, 1 cfu on RTE manipulated with wiped hands and absence on RTE manipulated with washed hands. This study provides adequate quantitative data for quantitative microbial risk assessment. [less ▲]

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See detailNUSAP: a method to evaluate the quality of assumptions in quantitative microbial risk assessment
Boone, Ides; Van der Stede, Yves; Dewulf, Jeroen et al

in Journal of Risk Research (2010), 13

implemented to evaluate assumptions in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. This QMRA model allows the testing of mitigation strategies for the ... [more ▼]

implemented to evaluate assumptions in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. This QMRA model allows the testing of mitigation strategies for the reduction of human salmonellosis and aims to serve as a basis for science-based policy making. The NUSAP method was used to assess the subjective component of assumptions in the QMRA model by a set of four pedigree criteria: ‘the influence of situational limitations’, ‘plausibility’, ‘choice space’ and ‘the agreement among peers’. After identifying 13 key assumptions relevant for the QMRA model, a workshop was organized to assess the importance of these assumptions on the output of the QMRA. The quality of the assumptions was visualized using diagnostic and kite diagrams. The diagnostic diagram pinpointed assumptions with a high degree of subjectivity and a high ‘expected influence on the model results’ score. Examples of those assumptions that should be dealt with care are the assumptions regarding the concentration of Salmonella on the pig carcass at the beginning of the slaughter process and the assumptions related to the Salmonella prevalence in the slaughter process. The kite diagrams allowed a clear overview of the pedigree scores for each assumption as well as a representation of expert (dis)agreement. The evaluation of the assumptions using the NUSAP system enhanced the debate on the uncertainty and its communication in the results of a QMRA model. It highlighted the model’s strong and weak points and was helpful for redesigning critical modules. Since the evaluation of assumptions allows a more critical approach of the QMRA process, it is useful for policy makers as it aims to increase the transparency and acceptance of management decisions based on a QMRA model. [less ▲]

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See detailChilling of carcasses from double muscled cattle: time-temperature evolution and predictive modelling of growth of Listeria monocytogenes and Clostridium perfringens
Delhalle, Laurent ULg; Collignon, Bertrand; Dehard, Sandrine ULg et al

Poster (2010)

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from ... [more ▼]

The time/temperature combination during carcass chilling is of concern in order to avoid bacterial growth. The chilling speed is lower in carcasses with high muscular development such as large cattle from the Belgian Blue breed. Three slaughterhouses were selected for temperature and pH measurements during the chilling process at 6 different days on 4 half carcasses in order to obtain representative data from heavy carcasses with high muscular development. Predictive microbiology was used to evaluate the potential growth of Listeria monocytogenes and Clostridium perfringens on the surface and in the depth of the carcasses. The gamma concept was chosen as secondary model taking into account the effect of temperature, pH and water activity on the selected bacteria during the chilling process. The predicted growth potential of Listeria monocytogenes is influenced by the different environmental conditions of the selected slaughterhouses and could reach 1.4 log CFU/cm² after the chilling process. The potential growth of Clostridium perfringens is limited due to unfavourable conditions during the first hours and to low temperature later. It can be concluded that when the initial level of contaminating bacteria is not excessive the speed at which the carcass is currently chilled is sufficient to limit the growth of these two pathogens and to ensure the product quality. [less ▲]

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See detailDéveloppement d'un modèle tertiaire pour la prédiction de la croissance de Listeria monocytogenes et Salmonella spp. dans la viande hachée de porc
Delhalle, Laurent ULg; Adolphe, Ysabelle ULg; Jasick, Adeline ULg et al

in Viandes et Produits Carnés (2010), Hors-série

Tertiary models are proposed in order to predict the growth of Listeria monocytogenes and Salmonella spp. in pork minced meat packaged under stretch film. The models have been calculated from challenge ... [more ▼]

Tertiary models are proposed in order to predict the growth of Listeria monocytogenes and Salmonella spp. in pork minced meat packaged under stretch film. The models have been calculated from challenge-tests at 8°C (L. monocytogenes) and 12°C (Salmonella), the meat being artificially contaminated at 2 log cfu pathogen/g. In a second step, they have been validated at 5, 8 and 10°C for L. monocytogenes (r² : 0.94, 0.98 and 0.95) and 8, 10 and 12°C for Salmonella (r³ : 0.80, 0.92 and 0.98). [less ▲]

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See detailQuality assurance in quantitative microbial risk assessment
Boone, Idesbald; Van der Stede, Yves; Aerts, Marc et al

in Vlaams Diergeneeskundig Tijdschrift (2010), 79

Quantitative microbial risk assessment (QMRA) is being used to estimate the risk level of pathogens along the food chain and to support management decisions for the reduction of food-safety risks. The ... [more ▼]

Quantitative microbial risk assessment (QMRA) is being used to estimate the risk level of pathogens along the food chain and to support management decisions for the reduction of food-safety risks. The degree of credibility that can be attached to risk assessment results depends largely on the quality and quantity of the data, the model structure and the assumptions taken. Quality Assurance (QA) in QMRA is fulfilled when all steps in the QMRA process are technically and scientifically valid, so that it can meet its objectives. An overview of QA methods for QMRA is presented. Whereas sensitivity analysis and scenario analysis are common in QMRA, formal methods for the evaluation of data quality, the critical evaluation of assumptions, structured expert elicitation, the checklist approach, and peer review are rarely applied in QMRA but could largely improve the transparency in the results of QMRAs. The degree of implementation of these methods should be proportionate to the stakes of the risk management questions, and discussed in consultation between risk assessors and risk managers. [less ▲]

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See detailThe POLYGAL project : optimization of food conservation using a combination of lactates and polyphenols.
Dure, Rémi ULg; Ladeuze, S.; Martin, E. et al

Poster (2009, November)

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See detailQuantifying hand cross contamination in food.
Rodrigues, Ana; Dure, Rémi ULg; Delhalle, Laurent ULg et al

Poster (2009, June)

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See detailValidation of methods for the detection of new emerging pathogenic Escherichia coli
Verstraete, K; De Reu, K; Robyn, J et al

Book published by Brussels : Belgian Science Policy (2009)

Enterohaemorrhagic Escherichia coli (EHEC) are shigatoxin producing E. coli (STEC) that can cause serious disease to humans. These food-borne pathogens belong to the fifth most common zoonoses in Belgium ... [more ▼]

Enterohaemorrhagic Escherichia coli (EHEC) are shigatoxin producing E. coli (STEC) that can cause serious disease to humans. These food-borne pathogens belong to the fifth most common zoonoses in Belgium, but due to their severe clinical symptoms in humans they are highly dreaded. They can cause a range of disease symptoms ranging from asymptomatically carriage over various diarrhoea symptoms to the life-threatening HUS (haemolytic uremic syndrome). Cattle are the main reservoir and infection of humans occurs through contact with faecal excretion material and consumption of contaminated food or water. A broad variety of serotypes is able to cause human infections, but the principal serotypes are O26, O103, O111, O145 and O157. These strains are denoted as new emerging pathogens by the WHO. The group of sorbitol non-fermenting (s-) O157:H7 strains are examined the most, because an ISO-method is available. For sorbitol fermenting (s+) O157 strains as well as for non-O157 STEC strains recently a new isolation method was developed in the Belspo project SD/AF/06A (Possé et al. 2008a). The aim of the project was the optimization and the validation of the above-mentioned detection and isolation method for STEC in different matrices. In the first place immunomagnetic separation (IMS) was evaluated for the optimization of the STEC isolation method for cattle faeces (Ghent University, UGent). Second, molecular characterization of STEC strains was performed using a newly designed 33-mPCR as an alternative tool (University of Antwerp, VIB) and pulsed field gel electrophoresis (PFGE) (Institute for Agricultural and Fisheries Research, ILVO). Also a smaller derived multiplex PCR (9-mPCR) was designed (VIB) and optimized for the screening of samples (ILVO). The third goal was the evaluation of different approaches for STEC isolation from human faecal samples (Universitair Ziekenhuis Brussel, UZ). Finally the STEC detection and isolation method was validated by an in-house and an interlaboratory study which was based on the ISO 16140 guideline for the validation of alternative methods (University of Liège; UGent; ILVO). For the optimization of the STEC isolation protocol for cattle faeces and the evaluation of the effect of IMS, cattle faecal samples were artificially inoculated with various numbers of STEC (10-100 and 100-1000 cfu/25g faeces) and isolated using the isolation protocol with 6h or 24h of enrichment followed by IMS and plating or direct plating on selective agars. Two types of IMS beads (Dynabeads and Captivate beads) were tested. Results showed that IMS (any of the two types of beads) had a highly positive effect on the isolation of serotype O157 (s- and s+), whereas only a small or even a negative effect for non-O157 serotypes was found. This was largely clarified by results on pure broth suspensions of STEC, showing that high percentages were recovered from the IMS beads used in suspensions with the serotypes O157 (s- and s+), O26 and O103, but lower percentages were recovered for O111 and O145. Non-O157 STEC were often already efficiently isolated from faeces using only direct plating, whereas O157 (s- and s+) STEC were not. For the enrichment time, 24h generally gave higher isolation efficiencies than 6h. Finally for serotypes O157 (s- and s+), O26 and O103, a level of 10-100 cfu/25g was reliably detected, whereas for serotypes O111 and O145 only 100-1000 cfu/25g was reliably detected. To accomplish the second task of the project, the Applied Molecular Genomics Group of the VIB Department of Molecular Genetics (UA-VIB) designed a proprietary 33-amplicon multiplex PCR (mPCR) assay combined with capillary electrophoresis. This mPCR assay contains the detection of 5 STEC serotypes (O26, O103, O111, O145, O157), the main virulence genes VT1 with variants (VT1ab, VT1c and VT1d), VT2 with six variants (VT2b,c,d,e,f,g) and consensus, eae with five variants (eaeα1, eaeβ1, eaeγ1; eaeγ2; eaeε and eaeζ), ehx, tir, katP, saa, espP and FliC H2, H7, H8, H11 and H28. The assay was optimized and validated on a set of test strains representative for the priority amplicons. Next, this molecular technology was validated on a collection of 334 human clinical and animal strains from the Belgian STEC Reference Center (UZ). This collection of human and animal strains was also characterized by performing the PulseNet Europe protocol for pulsed field gel electrophoresis (PFGE). This technique creates a fingerprint of a strain by means of rare cutter restriction enzyme cutting of DNA and gel electrophoresis. Analysis of the band patterns lead to clustering of strains according to similarity or relatedness. Then results of 33-mPCR and PFGE genotyping were combined to show eventual correlations between PFGE genotypes and virulence profiles. Also background information about the strains (date of isolation, human or animal source, clinical manifestation, outbreak information) was included to the analysis. Combining mPCR and PFGE genotyping results, correlations were shown. In the first place STEC strains were clustered according to their serotype. Secondly a correlation occurred between virulence profile and PFGE clustering, concerning VT genes and other genes. Particularly for STEC O157, strains had very diverse VT-profiles, and strains with the same VT-profile clustered together. Concerning the clinical manifestation, ‘asymptomatic’ cases occurred more frequently for non-O157 than for O157 STEC, but besides this no correlation was shown between the PFGE clustering and the clinical manifestation or between the VT-profile and the clinical manifestation. Finally several case studies could be appointed based on the PFGE dendrograms. In general the cases contained clones that persisted during several years, had similar virulence profiles and infected humans as well as animals. As a part of the second task, the UA-VIB also designed a derived 9-amplicon multiplex PCR (9-mPCR) for fast sample screening. Using this 9-mPCR, a combination of serotypes (O26, O103, O111, O145, O157) and virulence genes (VT1, VT2, eae and ehx) is detected in one run and can be visualized using conventional gel electrophoresis. Once the 9-mPCR was developed and tested on pure strains, an evaluation on samples was performed. Hereto ILVO (Institute for Agricultural and Fisheries Research) tested several methods to extract DNA from artificially inoculated samples. Methods were compared based on the ability to remove PCR inhibiting molecules and on the ability to isolate and purify DNA from STEC cells. Out of four methods only two methods, in which no removal of sample debris was done, were suitable for sample preparation. The method using bead beating cell lysis described by Yu and Morrison (2004), was at least 10 times more sensitive than the method using the Qiagen Stool Mini Kit according to the manufacturer’s instructions, and was therefore recommended. However, the method using bead beating cell lysis is much more time consuming than the Qiagen method and the use of a ribolyser is necessary. As ILVO used the method employing the ribolyser in all following experiments, this method was used on artificially inoculated samples to determine its detection limit. All virulence marker genes and the serotype gene of strain MB3901 (serotype O157) could be detected in enriched minced beef and cheese from raw milk artificially inoculated with 2 cfu/25g sample. For cattle fecal samples the screening test was 10 times less sensitive; 21 cfu/25g feces could be detected. Finally the influence of the volume of lysate used in the mPCR reaction mix was examined. An mPCR reaction containing 1 and 2µl of lysate DNA was performed, but no difference in detection was seen. Testing of different clinical isolates of non-O157 STEC on the newly designed selective agars, showed that growth characteristics were generally as expected. However, more standardization of the preparation of the medium is needed to obtain more reproducible results. Some O103 isolates did not grow on the media prepared at UZ and the color of the colonies of O111 was often difficult to distinguish from O26. Using artificially contaminated stool samples, the sensitivity of the STEC isolation protocol developed in a previous Belspo SPSD II project was similar to the protocol used routinely at UZ (103 and 104 cfu/5g). The sensitivity was about 10 times higher when using IMS. The method performed well on frozen STEC positive samples, but this could only be tested on 14 samples, of which 11 with O157, 2 with O111 and one O26. In-house validation of the STEC isolation protocol was performed to evaluate if the protocol is applicable for different types of food matrices. All samples used for this validation were artificially contaminated. Ten samples of minced beef, raw milk cheese and sprouted seeds were artificially inoculated with varying numbers (10-2000 cfu/25g) of non-stressed and stressed strains belonging to the serotypes O157 (s-) and (s+), O26, O103, O111 and O145. Cultured STEC strains were cold and freeze stressed by storing them for at least 5 days at respectively 2 and -18°C. Inoculated samples were pre-enriched in a weak selective medium for 6 hours followed by enrichment in a stronger selective medium for 18 hours. Direct plating on a selective medium was performed after each enrichment step. In a third pathway, an IMS (Dynabeads or Captivate beads) step was performed after 24h enrichment and prior to plating. Suspected colonies on the selective medium were purified and tentatively confirmed on a purification medium followed by a confirmation by a serotype PCR. Parallel to the classical isolation method, the 9-mPCR screening test was performed on the enrichment medium (after 24 hours enrichment). Results indicate that the isolation protocol as well as mPCR screening provide good detection of non-stressed and cold-stressed O26, O103, O157 (s+) and O145 in raw milk cheese and minced beef. Detection of the other non-stressed and cold-stressed serotypes (O111 and O157 (s+)) in raw milk cheese and minced beef and of all serotypes under freeze stressed conditions in minced beef was low or almost zero. Probably due to the high level of background flora, detection of any serotype in sprouted seeds was almost impossible even though inoculation numbers were as high as 2000 cfu/25g. Finally the optimized STEC detection and isolation methods were validated by an interlaboratory study performed by national and international laboratories (twelve laboratories in total). First, a pre-trial experiment was organized to give the collaborative laboratories the possibility to become familiar with the isolation method. Secondly, the actual interlaboratory study was performed. Products necessary to prepare all culture media (in-house-prepared: IHP) and ready-to-use selective agar culture media (ready-to-use: RTU) were sent to the participating laboratories, as well as a questionnaire and a document to report the results. For each participating laboratory, 20 samples of 25g of minced beef were prepared: one sample for the temperature measurement upon arrival, one for the enumeration of the total count, Enterobacteriaceae and E. coli, two blank samples and sixteen samples inoculated with single strains belonging to 4 serotypes at 2 levels of contamination in duplicate (30 cfu/g and 300 cfu/g). All strains were cold stressed. Samples were prepared the day of the shipment and had to be analyzed on a prefixed day. The University of Liège evaluated all results based on the recommendations of ISO 16140. Results showed no difference between RTU and IHP media. The arabinose test seemed difficult to be read, so the dulcitol test is now preferred for the confirmation of serotypes O103 and O111. Some mistakes were made during sample inoculation, like a wrong inoculation of four samples and no inoculation of one sample. If we do not take into account these mistakes, all four serotypes were detected with high sensitivity. In general it can be concluded that the laboratory performance is highly satisfactory. [less ▲]

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See detailMETZOON : Development of a quantitative microbial risk assessment for human salmonellosis through household consumption of fresh minced pork méat in Belgium.
Bollaerts, Kaatje; Messens, Winy; Delhalle, Laurent ULg et al

in Risk Analysis : An Official Publication of the Society for Risk Analysis (2009), 29(6), 820-840

A quantitative microbial risk assessment according to the Codex Alimentarius Principles is conducted to evaluate the risk on human salmonellosis through household consumption of fresh minced pork meat in ... [more ▼]

A quantitative microbial risk assessment according to the Codex Alimentarius Principles is conducted to evaluate the risk on human salmonellosis through household consumption of fresh minced pork meat in Belgium. The quantitative exposure assessment is carried out by building a modular risk model, called the METZOON-model, which covers the pork production from farm to fork. In the METZOON-model, the food production pathway is split up in six consecutive modules: (1) primary production, (2) transport & lairage, (3) slaughterhouse, (4) post-processing, (5) distribution & storage and (6) preparation & consumption. All the modules are developed to resemble as closely as possible the Belgian situation making use of the available national data. Several statistical refinements and improved modeling techniques are proposed. The model produces highly realistic results. The baseline predicted number of annual salmonellosis cases is 20513 [st. dev. 9061.45]. The risk is estimated higher for the susceptible population [est. 4.713 × 10−5; st. dev. 1.466 × 10−5] compared to the normal population [est. 7.704 × 10−6; st. dev. 5.414 × 10−6] and is mainly due to cross contamination via cook’s hands and only for a small extent to undercooking. [less ▲]

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See detailNUSAP Method for Evaluating the Data Quality in a Quantitative Microbial Risk Assessment Model for Salmonella in the Pork Production Chain
Boone, Ides; Van der Stede, Yves; Bollaerts, Kaatje et al

in Risk Analysis : An Official Publication of the Society for Risk Analysis (2009), 29

The numeral unit spread assessment pedigree (NUSAP) system was implemented to evaluate the quality of input parameters in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in ... [more ▼]

The numeral unit spread assessment pedigree (NUSAP) system was implemented to evaluate the quality of input parameters in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. The input parameters were grouped according to four successive exposure pathways: (1) primary production (2) transport, holding, and slaughterhouse, (3) postprocessing, distribution, and storage, and (4) preparation and consumption. An inventory of 101 potential input parameters was used for building the QMRA model. The characteristics of each parameter were defined using a standardized procedure to assess (1) the source of information, (2) the sampling methodology and sample size, and (3) the distributional properties of the estimate. Each parameter was scored by a panel of experts using a pedigree matrix containing four criteria (proxy, empirical basis, method, and validation) to assess the quality, and this was graphically represented by means of kite diagrams. The parameters obtained significantly lower scores for the validation criterion as compared with the other criteria. Overall strengths of parameters related to the primary production module were significantly stronger compared to the other modules (the transport, holding, and slaughterhouse module, the processing, distribution, and storage module, and the preparation and consumption module). The pedigree assessment contributed to select 20 parameters, which were subsequently introduced in the QMRA model. The NUSAP methodology and kite diagrams are objective tools to discuss and visualize the quality of the parameters in a structured way. These two tools can be used in the selection procedure of input parameters for a QMRA, and can lead to a more transparent quality assurance in the QMRA. [less ▲]

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