Boulogne-sur-Mer, France
Boulogne-sur-Mer, France

Time filter

Source Type

Clarisse T.,Agrocampus Ouest | Michele S.,Chimie Paristech | Olivier T.,French National Institute for Agricultural Research | Valerie E.,French National Institute for Agricultural Research | And 4 more authors.
Food Control | Year: 2013

Staphyloccocus aureus is reported to be one of the most frequent pathogens involved in food-borne diseases associated with dairy products, especially with raw milk cheese. Some strains produce enterotoxins as Staphylococcal enterotoxin A (SEA) which is involved in 75% of food poisoning outbreaks. Actually few methods are both sensitive and specific enough for confirming the diagnosis of staphylococcal food poisoning. In this work, an Enzyme-Linked ImmunoSorbent Assay (ELISA) was set up and optimised to detect SEA in milk and cheese. Various anti-SEA antibodies: polyclonal sera, anti-peptide polyclonal sera and monoclonal antibodies, used for the capture and or detection steps were compared and analysed. The mouse anti-whole SEA polyclonal serum, used as detection detected 32 pg/ml SEA in buffer and 64 pg/ml in milk. These concentrations were well under the limit set for food safety. This assay was also highly specific of SEA and no cross-reaction was observed with the other staphylococcal enterotoxins. In contaminated cheese samples the time of enterotoxin extraction was reduced by using ultrafiltration method instead of dialysis and the detection limits were 1.5-2.5 and 1.9-3 times more sensitive than a commercial kit and the official method, respectively. Preliminary study of SEA detection with the piezoelectric immunosensor allowed detecting and quantifying SEA within 10 min in unprocessed food but the sensitivity was not sufficient. The ELISA assay with mouse antibodies is likely suitable for SEA routine detection not only in dairy product but also in various foods as sauce and liver mousse. © 2012 Elsevier Ltd.


Habimana O.,French National Institute for Agricultural Research | Habimana O.,Agro ParisTech | Habimana O.,Nofima Materials AS | Guillier L.,Laboratoire Of Securite Des Aliments | And 4 more authors.
Biofouling | Year: 2011

Surfaces in industrial settings provide a home for resident biofilms that are likely to interact with the attachment, growth and survival of pathogens such as Listeria monocytogenes. Experimental results have indicated that L. monocytogenes cells were inhibited by the presence of a model resident flora (Lactococcus lactis) in dual-species continuous flow-biofilms, and are spatially restricted to the lower biofilm layers. Using a new, simplified individualbased model (IBM) that simulates bacterial cell growth in a three-dimensional space, the spatial arrangements of the two species were reconstructed and their cell counts successfully predicted. This model showed that the difference in generation times between L. monocytogenes and L. lactis cells during the initial stages of dual-species biofilm formation was probably responsible for the species spatialization observed and the subsequent inhibition of growth of the pathogen. © 2011 Taylor & Francis.


Commeau N.,French National Institute for Agricultural Research | Commeau N.,Agro ParisTech | Commeau N.,Laboratoire Of Securite Des Aliments | Cornu M.,Agro ParisTech | And 3 more authors.
Risk Analysis | Year: 2012

Assessing within-batch and between-batch variability is of major interest for risk assessors and risk managers in the context of microbiological contamination of food. For example, the ratio between the within-batch variability and the between-batch variability has a large impact on the results of a sampling plan. Here, we designed hierarchical Bayesian models to represent such variability. Compatible priors were built mathematically to obtain sound model comparisons. A numeric criterion is proposed to assess the contamination structure comparing the ability of the models to replicate grouped data at the batch level using a posterior predictive loss approach. Models were applied to two case studies: contamination by Listeria monocytogenes of pork breast used to produce diced bacon and contamination by the same microorganism on cold smoked salmon at the end of the process. In the first case study, a contamination structure clearly exists and is located at the batch level, that is, between batches variability is relatively strong, whereas in the second a structure also exists but is less marked. © 2012 Society for Risk Analysis.


Commeau N.,French National Institute for Agricultural Research | Commeau N.,Laboratoire Of Securite Des Aliments | Commeau N.,Agro ParisTech | Parent E.,French National Institute for Agricultural Research | And 4 more authors.
International Journal of Food Microbiology | Year: 2012

To fit a lognormal distribution to a complex set of microbial data, including detection data (e.g. presence or absence in 25. g) and enumeration data (e.g. 30. cfu/g), we compared two models: a model called MCLD based on data expressed as concentrations (in cfu/g) or censored concentrations (e.g < 10. cfu/g, or >. 1. cfu/25. g) versus a model called MRD that directly uses raw data (presence/absence in test portions, and plate colony counts). We used these two models to simulated data sets, under standard conditions (limit of detection (LOD) = 1. cfu/25. g; limit of quantification (LOQ) = 10. cfu/g) and used a maximum likelihood estimation method (directly for the model MCLD and via the Expectation-Maximisation (EM) algorithm for the model MRD. The comparison suggests that in most cases estimates provided by the proposed model MRD are similar to those obtained by model MCLD accounting for censorship. Nevertheless, in some cases, the proposed model MRD leads to less biased and more precise estimates than model MCLD. © 2012 Elsevier B.V.


PubMed | Laboratoire Of Securite Des Aliments, University Bretagne Loire, Institute Pasteur Paris and Labocea
Type: Journal Article | Journal: PloS one | Year: 2017

Liver is a reliable matrix for laboratory confirmation of avian botulism using real-time PCR. Here, we developed, optimized, and validated the analytical steps preceding PCR to maximize the detection of Clostridium botulinum group III in avian liver. These pre-PCR steps included enrichment incubation of the whole liver (maximum 25 g) at 37C for at least 24 h in an anaerobic chamber and DNA extraction using an enzymatic digestion step followed by a DNA purification step. Conditions of sample storage before analysis appear to have a strong effect on the detection of group III C. botulinum strains and our results recommend storage at temperatures below -18C. Short-term storage at 5C is possible for up to 24 h, but a decrease in sensitivity was observed at 48 h of storage at this temperature. Analysis of whole livers (maximum 25 g) is required and pooling samples before enrichment culturing must be avoided. Pooling is however possible before or after DNA extraction under certain conditions. Whole livers should be 10-fold diluted in enrichment medium and homogenized using a Pulsifier blender (Microgen, Surrey, UK) instead of a conventional paddle blender. Spiked liver samples showed a limit of detection of 5 spores/g liver for types C and D and 250 spores/g for type E. Using the method developed here, the analysis of 268 samples from 73 suspected outbreaks showed 100% specificity and 95.35% sensitivity compared with other PCR-based methods considered as reference. The mosaic type C/D was the most common neurotoxin type found in examined samples, which included both wild and domestic birds.


Granier S.A.,Laboratoire Of Securite Des Aliments | Hidalgo L.,Complutense University of Madrid | Millan A.S.,Complutense University of Madrid | Escudero J.A.,Complutense University of Madrid | And 3 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2011

The 16S rRNA methyltransferase ArmA is a worldwide emerging determinant that confers high-level resistance to most clinically relevant aminoglycosides. We report here the identification and characterization of a multidrug-resistant Salmonella enterica subspecies I.4,12:i:- isolate recovered from chicken meat sampled in a supermarket on February 2009 in La Reunion, a French island in the Indian Ocean. Susceptibility testing showed an unusually high-level resistance to gentamicin, as well as to ampicillin, expanded-spectrum cephalosporins and amoxicillin-clavulanate. Molecular analysis of the 16S rRNA methyltransferases revealed presence of the armA gene, together with bla TEM-1, bla CMY-2, and bla CTX-M-3. All of these genes could be transferred en bloc through conjugation into Escherichia coli at a frequency of 10 -5 CFU/donor. Replicon typing and S1 pulsed-field gel electrophoresis revealed that the armA gene was borne on an ~150-kb broad-host-range IncP plasmid, pB1010. To elucidate how armA had integrated in pB1010, a PCR mapping strategy was developed for Tn1548, the genetic platform for armA. The gene was embedded in a Tn1548-like structure, albeit with a deletion of the macrolide resistance genes, and an IS26 was inserted within the mel gene. To our knowledge, this is the first report of ArmA methyltransferase in food, showing a novel route of transmission for this resistance determinant. Further surveillance in food-borne bacteria will be crucial to determine the role of food in the spread of 16S rRNA methyltransferase genes worldwide. Copyright © 2011, American Society for Microbiology. All Rights Reserved.


Guillier L.,Laboratoire Of Securite Des Aliments | Danan C.,Laboratoire Of Securite Des Aliments | Bergis H.,Laboratoire Of Securite Des Aliments | Delignette-Muller M.-L.,University Claude Bernard Lyon 1 | And 5 more authors.
International Journal of Food Microbiology | Year: 2013

A major community outbreak of salmonellosis occurred in France in October 2010. Classical epidemiological investigations led to the identification of beef burgers as the cause of the outbreak and the presence of the emerging monophasic Salmonella Typhimurium 4,5,12:i:-The objective of this study was to understand the events that led to this large outbreak, that is to say, what are the contributing factors associated with consumer exposure to Salmonella. To this end, intensive microbiological investigations on several beef burgers were conducted and a risk assessment model was built.The microbiological results confirm the presence of Salmonella in all analysed frozen burgers at high levels of contamination above 1000MPN/g. These results in frozen burgers combined with a model of thermal destruction were used to estimate the dose ingested by the exposed persons. Most people that consumed cooked beef burgers were exposed from 1.6 to 3.1log10 (MPN). The number of sick people predicted with a dose-response relationship for Salmonella is consistent with the observed number of salmonellosis cases.The very high initial contamination level in frozen beef burgers is the primary cause of this large outbreak rather than bad cooking practices. Intensive investigations, modelling of the initial contamination and quantitative exposure and risk assessments are complementary to epidemiological investigation. They can be valuable elements for the assessment of missing information or the identification of the primary causes of outbreaks. © 2013.


Gossner C.M.,Institute of Veille Sanitaire | Gossner C.M.,U.S. Center for Disease Control and Prevention | van Cauteren D.,Institute of Veille Sanitaire | le Hello S.,Institute Pasteur Paris | And 8 more authors.
Eurosurveillance | Year: 2012

An outbreak of the monophasic variant of Salmonella enterica serotype 4,[5],12:i:- occurred in November and December 2011 in France. Epidemiological investigation and food investigation with the help of supermarket loyalty cards suggested dried pork sausage from one producer as the most likely source of the outbreak. Despite the absence of positive food samples, control measures including withdrawal and recall were implemented.


Dehaut A.,Laboratoire Of Securite Des Aliments | Midelet-Bourdin G.,Laboratoire Of Securite Des Aliments | Brisabois A.,Laboratoire Of Securite Des Aliments | Duflos G.,Laboratoire Of Securite Des Aliments
Letters in Applied Microbiology | Year: 2014

Four strains were isolated from a spoiled whiting (Merlangius merlangus). All of them were able to grow aerobically from 4 to 30°C and also able to develop anaerobically in the presence of trimethylamine N-Oxide (TMAO) at 25°C. Biochemical characterization did not allow identification of the strains species but showed that one of the four strains was unable to produce H2S. Two strains synthetized an ornithine decarboxylase being potential putrescine producers. Results of carbon source use highlighted that the four strains were able to use citrate and d-sucrose and one strain was not able to use l-arabinose. Genotypic characterization of the strains thanks to 16S rRNA and gyrB partial gene sequencing led to their identification as members of Shewanella baltica species. These observations suggest that H2S production may not be the most appropriate screening parameter for Shewanella species and further to monitor the development of spoilage flora. Significance and Impact of the Study: Shewanella is a complex genus composed of numerous and heterogeneous species. One of them Shewanella baltica has previously been described as one of the most important H2S-producing bacterial species in iced stored fish and may act as spoilage organism through the reduction of trimethylamine N-Oxide (TMAO). Four strains of S. baltica were isolated from spoiled whiting (Merlangius merlangus), and description of three H2S-positive strains and one H2S-negative strain of S. baltica is highlighted in this short paper. Consequently, H2S production might not be the most appropriate screening parameter to assess the development of spoilage organisms. © 2014 The Society for Applied Microbiology.


Arnich N.,French Agency for Food | Sirot V.,French Agency for Food | Riviere G.,French Agency for Food | Jean J.,French Agency for Food | And 3 more authors.
Food and Chemical Toxicology | Year: 2012

Dietary exposure of the French population to trace elements has been assessed in the second national Total Diet Study (TDS). Food samples (n= 1319) were collected between 2007 and 2009 to be representative of the whole diet of the population, prepared as consumed, and analyzed. Occurrence data were combined with national individual consumption data to estimate dietary exposure for adults and children mean and high consumers. Compared to the 1st French TDS performed in 2000-2004, exposure is higher for cadmium, aluminium, antimony, nickel, cobalt and lower for lead, mercury and arsenic. For aluminium, methylmercury, cadmium, lead and inorganic arsenic risk cannot be ruled out for certain consumer groups. It still appears necessary to continue undertaking efforts to reduce exposure to these elements. Due to the lack of robust toxicological data and/or speciation analysis in food on chromium, tin, silver and vanadium to perform a risk assessment, data on occurrence and dietary exposure are provided as Supplementary material. In order to minimize nutritional and chemical risks, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) reiterates its recommendation for a diversified diet (food items and origins). © 2012 Elsevier Ltd.

Loading Laboratoire Of Securite Des Aliments collaborators
Loading Laboratoire Of Securite Des Aliments collaborators