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A Salmonella database to monitor and centralize regulatory own-checks results (CE) n° 2073/2005 obtained by slaugterhouse

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Sabine Itié-Hafez (Ministère de l'Agriculture) et Alain Le Roux (Ifip), 13e SafePork, 26-29 août 2019, Berlin, Allemagne, poster

Salmonellosis is a major cause of foodborne outbreaks caused by bacteria in Europe. In 2014, the European Commission reinforced the survey of this contaminant in the pig and pork industry by the competent authority. In this context, French General Directorate for Food required a new system to centralize regulatory own-checks results for Salmonella in pig carcasses.

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2019

Effect of a beneficial flora colonization of pen surfaces on health and performance of pig weaners

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Eric Royer (ancien Ifip, aujourd'hui Idele) et al., 70th Annual Meeting of the European Federation of Animal Science (EAAP), 26-30 octobre 2019, Ghent, Belgique, p. 566

The objective was to test the effects of a positive biofilm formation on the surfaces of post-weaning piglet facilities.
In total, 494 piglets were used in two experiments using a sanitary challenge. 48 h (d-2) before introduction of piglets, 2 identical rooms of 14 pens were sprayed either with water (Control) or a mix (LP) of selected bacteria strains.
Rooms were exchanged between Exp.1 and Exp.2. In Exp.1 rooms were sprayed again at d 15 and in Exp.2 at d 5, 12, 19, 26 and 33. Environmental challenge for piglets was stronger in Exp.1 than in Exp.2. Wiping samples indicated significantly (P<0.05) higher loads of aerobic bacteria (Lactobacillus spp., Bacillus spp.) in LP pen surfaces in Exp.1 at d 0, 5, and 14 and at d 0, 5, 7 and 35 in Exp.2, suggesting the development of the positive biofilm. Percentage of piglets with regular consistency of faeces was continuously higher in LP rooms in Exp.1 (from d 8 to 21) and Exp.2 (from d 5 to 28). Furthermore, mean scores were significantly improved at d 8 in Exp.1 (3.13 vs 4.50; P<0.01) and in Exp.2 at d 9 (2.19 vs 3.19; P=0.01) and 28 (2.03 vs 2.50; P<0.01). Disease outbreaks occurred two days later in Exp.1 (d 9 vs 7) and five days later in Exp.2 (d 12 vs 7) in LP rooms. However, total numbers of deaths from diarrhoea were similar in both treatments in Exp.1 and 2. In Exp.1, LP piglets had numerically better overall ADFI (794 vs 781 g/d; P>0.10) and ADG (510 vs 499 g/d; P>0.10), and had slightly higher weight at d 42 (29.8 vs 29.4 kg; P>0.10). In Exp.2, ADFI (259 vs 219 g/d; P<0.001) and ADG (211 vs 154 g/d; P<0.001) were significantly increased in the LP treatment in phase 1 (d 0 to 15). Weight was significantly higher for LP piglets at d 15 (11.9 vs 11.0 kg; P<0.001), although it was similar at d 41 (P>0.10). In conclusion, the spraying of a beneficial flora on surfaces may result in a protective positive biofilm that would help the piglets to deal better with the weaning challenges.

PDF icon Eric Royer (ancien IFIP, aujourd'hui Idele) et al., 70th EAAP, 26-30 octobre 2019, Ghent, Belgique, p. 566
2019

Development of a quantative PCR method coupled with PMA to quantify viable Salmonella spp. cells in the pork supply chain

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Sabine Jeuge et al., 13e SafePork, 26-29 août 2019, Berlin, Allemagne

In 2017, Salmonella spp. was implied in 30% of foodborne diseases in France (SPF, 2019). Few data on the contamination levels of Salmonella spp., are available along the pork supply chain. The protocol of the standard method (ISO/TS 6579-2:2012) is time-consuming and culture-based methods using chromogenic media are less efficient for matrices with high levels of back ground flora, and for recovering stressed cells. Along the food chain, the cells may be impacted by various stresses (e.g. chemical or thermal), which may lead to physiological changes and the emergence of viable but non-culturable cells (VBNCs).

PDF icon Sabine Jeuge et al., 13e SafePork, 26-29 août 2019, Berlin, Allemagne
2019

Influence of reduced levels or suppression of sodium nitrite on the growth of psychrotrophic Clostridium botulinum group II type B in cooked ham and frankfurters

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Sarah Lebrun (Université  de Liège) et al., 65th International Congress of Meat Science and Technology (ICOMST), 4-9 août 2019, Potsdam/Berlin, Allemagne, poster, p. 28

Sodium nitrite (NaNO2) is commonly used in meat products manufacturing for its antimicrobial effect on Clostridium botulinum, responsible of botulism (a deadly paralytic disease) by production of neurotoxins. Its use can nevertheless be associated with nitrosamines production, which are considered as carcinogenic substances (EFSA, The EFSA Journal, 2013, 14: 1-31). The objective of the present study was to compare the growth and toxinogenesis of psychrotrophic C. botulinum Group II (non-proteolytic) type B in cooked ham and in frankfurters in function of the NaNO2 incorporation rate (0, 30, 60 and 80 mg/kg) in order to evaluate the risk associated with this pathogen in two common cooked meat products.

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2019

Evaluation d’un outil moléculaire pour valider les mesures de maîtrise des salmonelles dans la filière

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Sabine Jeuge, bilan 2018, éditions IFIP, avril 2019, p. 45

En 2017, Salmonella spp. a été responsable de 30 % des toxi-infections alimentaires collectives selon Santé Publique France.
Peu de données quantitatives sont disponibles aux différents maillons de la filière porcine. La méthode de référence (ISO/TS 6579-2:2012) pour le dénombrement de Salmonella spp. présente l’inconvénient d’être chronophage avec un délai de 5 jours avant obtention du résultats de dénombrement. Les méthodes alternatives sur milieux chromogènes sont utilisables sur certaines matrices pauvres en flore annexe et ne permettent pas une récupération optimale des bactéries présentes mais stressées. Or, le long de la chaîne de l’élevage à la transformation de produit en passant par l’abattage, les bactéries subissent des nombreux stress entrainant des changements physiologiques, et un passage à l’état de bactéries viables mais non cultivables (VNC).
L’objectif de ce projet est, dans un premier temps, la mise au point d’une méthode de dénombrement des salmonelles pour les échantillons d’élevage (fèces) et les carcasses de porc basée sur une PCR TaqMan (qPCR) et avec un traitement par un marqueur de viabilité, le propidium monoazide (PMA) afin d’éliminer l’amplification d’ADN des bactéries mortes des matrices

PDF icon Sabine Jeuge, bilan 2018, éditions IFIP, avril 2019, p. 45
2019

Évaluation d’une méthode de quantification des bactéries viables de Listeria après désinfection

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Bastien Frémaux, bilan 2018, éditions IFIP, avril 2019, p. 47

Le nettoyage et la désinfection (N&D) des installations en agroalimentaire est une procédure fondamentale pour garantir la qualité et la sécurité sanitaire des aliments. La validation de l’efficacité des opérations de N&D repose le plus souvent sur un contrôle visuel de l’état de propreté des surfaces et sur la mise en oeuvre d’analyses microbiologiques classiques basées sur des méthodes culturales.
Il est aujourd’hui connu que certains stress, tels que l’exposition aux désinfectants, peuvent conduire à l’apparition de bactéries viables non cultivables (VNC), non détectées dans les procédures de contrôle actuelles. Leur présence non contrôlée sur les surfaces d’ateliers peut être problématique en cas de transfert à l’aliment en contact, où elles pourront se revivifier et se multiplier.
Ce programme visait (1) au développement et à la mise en oeuvre au laboratoire d’une méthode de PMA-PCRq pour la quantification des formes viables de L. monocytogenes, (2) à évaluer la PMAPCRq pour la quantification des formes viables (dont les non cultivables) de L.
monocytogenes
adhérentes en biofilm sur deux types de surface (acier inoxydable et PET) suite à l’exposition à 3 produits désinfectants largement employés dans l’industrie charcutière et plus généralement dans l’agroalimentaire : un alcalin chloré, une formulation à base d’ammonium quaternaire et de glutaraldéhyde et une formulation à base d’acide peracétique.
PDF icon Bastien Frémaux, bilan 2018, éditions IFIP, avril 2019, p. 47
2019

Diversité génétique des souches de Listeria isolées dans la filière porcine en France

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Carole Feurer, bilan 2018, éditions IFIP, avril 2019, p. 46

Listeria monocytogenes (Lm) est une bactérie responsable d’une zoonose rare mais grave appelée listériose qui cause 300 à 400 infections par an en France et s’avère mortelle dans 20 à 30% des cas. Elle touche principalement les personnes immunitairement affaiblies. La gravité de l’infection dépend de la dose et de la virulence du groupe génétique de la souche ingérée.
La contamination des aliments peut survenir à partir de matières premières animales ou végétales mais plus particulièrement à partir de l’environnement des sites de production dans lequel les souches de Lm sont capables de survivre, de persister et de s’implanter. La technique MLST (Multi Locus Sequence Typing) est devenue la méthode standardisée au niveau international pour analyser la structure génétique des populations de Lm. Fondée sur le polymorphisme de séquence de 7 gènes de ménage, cette méthode permet l’attribution d’un «complexe clonal» (CC) à une souche. En France, les CC1, CC2, CC4, CC6 sont décrits comme hyper virulents et fréquemment isolés de cas cliniques.
Les CC9 et CC121 sont quant à eux isolés plus fréquemment d’aliments que de cas cliniques. Les CC9 et CC121 sont prévalents dans tous les compartiments de production alimentaire.
Entre 2015 et 2017, l’Ifip en partenariat avec l’Anses de Maisons-Alfort ont mené une étude qui visait à obtenir une meilleure connaissance de la diversité des souches de Listeria monocytogenes (Lm) afin de mieux caractériser la manière dont elle circule dans la filière porcine.
PDF icon Carole Feurer, bilan 2018, éditions IFIP, avril 2019, p. 46
2019

Complete genome sequence of Salmonella enterica subsp. enterica Serotype Derby, associated with the pork sector in France

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Yann Sévellec et al., Microbiology Resource Announcements, volume 7, n° 12, septembre, 4 pages

In the European Union, Salmonella enterica subsp. enterica serovar Derby is the most abundant serotype isolated from pork. Recent studies have shown that this serotype is polyphyletic. However, one main genomic lineage, characterized by sequence type 40 (ST40), the presence of the Salmonella pathogenicity island 23, and showing resistance to streptomycin, sulphonamides, and tetracycline (STR-SSS-TET), is pork associated. Here, we describe the complete genome sequence of a strain from this lineage isolated in France.

https://mra.asm.org/content/ga/7/12/e01027-18.full-text.pdf

2018

Redlosses: reducing food losses by microbial spoilage prediction

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M. Zagorec (INRA) et al., EFFOST, 6-8 novembre 2018, Nantes

Food spoilage leads to significant wastes and losses, and is an important economic issue in food industry. In the case of meat, a large part of spoilage is the consequence of bacterial growth and subsequent metabolic activities causing organoleptic spoilage of the final product (defects in texture, color, odor, or aspect), leading finally to products that are lost because they do not fit the quality standards. In addition, meat production chain requires energy, water and cost consuming operations (i.e. animal breeding, slaughtering, and transformation and storage which are usually performed at low temperature). Therefore meat product spoilage that appears at the end of the process or during shelf life affects the whole production chain performances as well as the sustainability label of the meat sector. The objective of the project is to reduce food losses by predicting, early in the production process, the onset of bacterial spoilage during storage in order to propose decision-support tools for directing process. Pork and poultry meat, the two main meats consumed in France will be studied. The economic impact of losses of these products will be assessed. Dynamics of bacterial communities will be monitored during processing steps (from primary cuts to end products at use-by-date and beyond) and various descriptors of spoilage will be measured. The natural variability between batches and that associated with production processes will be considered. Data will be used to identify accurate spoilage markers and to compute innovative mathematical models for predicting spoilage occurrence as a function of the initial composition of the microbiota (diversity and abundance) and some abiotic factors (lactate concentration, nature of packaging atmosphere). The models will be validated on meat products, including the economic aspect in order to propose decision-support tools for the food producers. The project and first results will be presented.

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2018

Population genetic structure of Listeria monocytogenes strains isolated from the pig and pork meat production chain in France

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Benjamin Félix (Anses) et al., Food Micro, 3-6 septembre 2018, Berlin, Allemagne

Listeria monocytogenes is an ubiquitous pathogenic bacterium, transmissible to humans through the consumption of contaminated food. The pork production sector has been hit hard by a series of L. monocytogenes-related food poisoning outbreaks in France. An overview of the diversity of strains circulating at all levels of the pork production chain, from pig farming to finished food products, is needed to identify the contamination routes and improve food safety. Until now, no typing data has been available on strains isolated across the entire pig and pork production chain. 
Here, we analyzed the population genetic structure of 687 L. monocytogenes strains isolated over the last 20 years in virtually all the French départements from three compartments of this production sector: pig farming (PF), the food processing environment (FPE) and finished food products (FFP). The genetic structure was described based on MLST clonal complexes (CCs). The CCs were obtained by mapping the PFGE profiles of the strains. The distribution of CCs was compared firstly between the three compartments and then with CCs obtained from 1106 strains isolated from other food production sectors in France. 
The predominant CCs of pig and pork strains were not equally distributed among the three compartments: the CC37, CC59 and CC77 strains, rarely found in FPE and FFP, were prevalent in PF. The two most prevalent CCs in the FPE and FFP compartments, CC9 and CC121, were rarely or never detected in PF. No CC was exclusively associated with the pork sector. Three CCs (CC5, CC6, CC2) were considered ubiquitous, because they were observed in comparable proportions in all food production sectors. The two most prevalent CCs in all sectors were CC9 and CC121, but their distribution was disparate. CC9 was associated with meat products and food products combining several food categories, whereas CC121 was not associated with any given sector. Based on these results, CC121 is likely able to colonize a larger diversity of food products than CC9. Both CCs being associated with the food production suggests, that certain processing steps, such as slaughtering or stabilization treatments, favor their settlement and the recontamination of the food produced.

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2018

Ecology of Salmonella and antimicrobial resistance in a pig slaughterhouse

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Arnaud Bridier et al., Food Micro, 3-6 septembre 2018, Berlin, Allemagne et I3S, 24-26 septembre 2018, Saint-Malo, France

Salmonella is a bacterial pathogen responsible for a large number of food associated infections. In order to guarantee food safety, a better understanding of Salmonella ecology and adaptation strategies on the food production chain constitutes a prerequisite. In a One Health perspective, data on Salmonella antibiotic resistance in food environments are also crucial to decipher transmission routes of resistant foodborne pathogens as well as resistance genetic determinants involved, and the role of process and selection pressures underwent in food industries (as cleaning and disinfection) in bacterial adaptation and antimicrobial resistance emergence.
Using a pig slaughterhouse as a model food environment, occurrence of Salmonella was investigated at six different areas along the slaughter chain and through 4 sampling campaign, each time before and after cleaning and disinfection procedures (a total of 48 surface samples). Characterization of isolated Salmonella strains using serotyping and pulsotyping enabled to identify and trace persistent strains in the slaughterhouse. Minimal inhibiting concentrations (MIC) were also determined for various relevant antibiotics and for biocides used in the slaughterhouse. In addition, associated indigenous bacterial communities were characterized using 16S rRNA amplicon sequencing. 
Results revealed the presence of Salmonella at all sampling area. Five serotypes were identified: S.4,5,12:i:- (50%), Rissen (16%), Typhimurium (16%), Infantis (10%) and Derby (8%). Strains were found at different dates and potentially at the same sampling area suggesting they persist in the slaughterhouse despite of the cleaning and disinfection procedures. Approximately 70% of isolated Salmonella strains exhibit resistance to ampicillin and sulfamethoxazole, 80% to tetracycline and 10% to chloramphenicol. There was no evolution of CMI comparing strains before and after cleaning and disinfection procedures concerning both biocides and antibiotics. Bacterial diversity analyses showed that populations in slaughterhouse were highly dominated by &a1;-proteobacteria and especially by the Moraxellaceae family (genus Psychrobacter, Moraxella, Enhydrobacter and Acinetobacter) at the different sampling areas. Population compositions were overall stable in time at a given sampling area suggesting that the surface populations are resident populations within the slaughterhouse, rather than populations introduced each week by the new swine bands. Cleaning and disinfection procedures tend to reduce bacterial diversity by eliminating the minority species but did not greatly impact the composition of bacterial communities with regards to the dominant species.
Together, such data participate to the construction of a comprehensive view of Salmonella ecology in food environments integrating associated resident microbial flora and the distribution of antimicrobial resistance in relation to processing conditions.

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2018

Selection procedure of bioprotective cultures for their combined use with High Pressure Processing to control spore-forming bacteria in cooked ham.

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Mihanta Ramaroson et al., International journal of food microbiology, 2018, voluime 276, 2 juillet, p. 28-38

High Pressure Processing (HPP) and biopreservation can contribute to food safety by inactivation of bacterial contaminants. However these treatments are inefficient against bacterial endospores. Moreover, HPP can induce spore germination. The objective of this study was to select lactic acid bacteria strains to be used as bioprotective cultures, to control vegetative cells of spore-forming bacteria in ham after application of HPP. A collection of 63 strains of various origins was screened for their antagonistic activity against spore-forming Bacillus and Clostridium species and their ability to resist to HPP. Some safety requirements should also be considered prior to their introduction into the food chain. Hence, the selection steps included the assessment of biogenic amine production and antibiotic resistance. No strain produced histamine above the threshold detection level of 50 ppm. From the assessment of antibiotic resistance against nine antibiotics, 14 susceptible strains were kept. Antagonistic action of the 14 strains was then assessed by the well diffusion method against pathogenic or spoilage spore-forming species as Bacillus cereusClostridium sp. like botulinum, Clostridium frigidicarnis, and Clostridium algidicarnis. One Lactobacillus curvatus strain and one Lactococcus lactis strain were ultimately selected for their widest inhibitory spectrum and their potential production of bacteriocin. A Lactobacillus plantarum strain was included as control. Their resistance to HPP and ability to regrow during chilled storage was then assessed in model ham liquid medium. Treatments of pressure intensities of 400, 500, and 600 MPa, and durations of 1, 3, 6, and 10 min were applied. After treatment, cultures were incubated at 8 °C during 30 days. Inactivation curves were then fitted by using a reparameterized Weibull model whereas growth curves were modelled with a logistic model. Although the two Lactobacillus strains were more resistant than L. lactis to HPP, the latter was the only strain able to regrow following HPP. The absence of biogenic amine production of this strain after growth on diced cube cooked ham was also shown. In conclusion this L. lactis strain could be selected as representing the best candidate for a promising preservative treatment combining biopreservation and HPP to control spore-forming bacteria in cooked ham.

 
2018

Population Genetic Structure of Listeria monocytogenes Strains Isolated From the Pig and Pork Production Chain in France

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Benjamin Félix (Anses) et al., Frontiers in Microbiology, 2018, n° 9, 6 avril, 11 pages

Listeria monocytogenes is an ubiquitous pathogenic bacterium, transmissible to humans through the consumption of contaminated food. The pork production sector has been hit hard by a series of L. monocytogenes-related food poisoning outbreaks in France. An overview of the diversity of strains circulating at all levels of the pork production chain, from pig farming (PF) to finished food products (FFP), is needed to identify the contamination routes and improve food safety. Until now, no typing data has been available on strains isolated across the entire pig and pork production chain. Here, we analyzed the population genetic structure of 687 L. monocytogenes strains isolated over the last 20 years in virtually all the French départements from three compartments of this production sector: PF, the food processing environment (FPE), and FFP. The genetic structure was described based on Multilocus sequence typing (MLST) clonal complexes (CCs). The CCs were obtained by mapping the PFGE profiles of the strains. The distribution of CCs was compared firstly between the three compartments and then with CCs obtained from 1106 strains isolated from other food production sectors in France. The predominant CCs of pig and pork strains were not equally distributed among the three compartments: the CC37, CC59, and CC77 strains, rarely found in FPE and FFP, were prevalent in PF. The two most prevalent CCs in the FPE and FFP compartments, CC9 and CC121, were rarely or never detected in PF. No CC was exclusively associated with the pork sector. Three CCs (CC5, CC6, and CC2) were considered ubiquitous, because they were observed in comparable proportions in all food production sectors. The two most prevalent CCs in all sectors were CC9 and CC121, but their distribution was disparate. CC9 was associated with meat products and food products combining several food categories, whereas CC121 was not associated with any given sector. Based on these results, CC121 is likely able to colonize a larger diversity of food products than CC9. Both CCs being associated with the food production suggests, that certain processing steps, such as slaughtering or stabilization treatments, favor their settlement and the recontamination of the food produced. 

https://www.frontiersin.org/articles/10.3389/fmicb.2018.00684/pdf

2018

Prévalence des Staphylococcus aureus résistants à la méticilline (SARM) sur carcasses de porc en abattoirs

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Carole Feurer, bilan 2017, éditions IFIP, mai 2018, p. 82-83

En France en 2015, l’agent responsable de toxi-infections alimentaires collectives (TIAC) le plus fréquemment suspecté ou avéré était l’entérotoxine staphylococcique (33% des 1 390 foyers de TIAC) (InVS, 2015).
Staphylococcus aureus appartient au groupe des staphylocoques à coagulase positive (SCP), pathogènes pour l’Homme. S. aureus est un germe commensal de la peau et des muqueuses de l’homme et de la plupart des animaux.
Staphylococcus aureus peut être considéré comme un agent zoonotique, cependant les souches isolées lors d’intoxinations ont très majoritairement une origine humaine (contamination de l’aliment par l’homme au cours du procédé ou lors de sa préparation avant consommation) (Anses, 2011). Le rôle pathogène de S. aureus est lié à la production d’entérotoxines (ES) staphylococciques. Vingt-six ES (SEA à SEY) ont été décrites et sont toutes hautement toxiques.
Il existe un Staphylococcus aureus résistant à la méthicilline (SARM), ce variant est pratiquement résistant à toutes les bétalactamines.
En France, les résultats des différentes enquêtes disponibles montrent que les porcs sont d’importants réservoirs de souches de SARM.
En 2014, une étude menée par l’Ifip a montré que dans un abattoir, sur 189 carcasses prélevées par chiffonnage d’une demi-carcasse (1 m²) avant entrée en découpe, réparties sur 10 journées d’abattage, les staphylocoques à coagulase positive (SCP) étaient dénombrés sur 43,4% [36,5 - 50,5] des carcasses, avec des nombres très faibles compris entre 0,01 et 2 UFC/cm2. Cependant, les souches isolées n’ont pas été caractérisées pour leur appartenance à l’espèce S. aureus ni leur capacité de production d’entérotoxines.
Les SARM étaient quant à eux isolés sur 87,3% [82 - 91,5] des carcasses. La très forte fréquence de SCP et de SARM observée sur carcasse dans cet abattoir nous a amené à nous interroger sur l’origine de cette contamination : liée à un portage cutané ou à des contaminations croisées localisées lors de la manipulation des têtes en sortie de réfrigération.
Ces résultats préliminaires nécessitaient d’être confirmés dans un plus grand nombre d’abattoirs.
Ainsi ce projet visait à déterminer le taux de prévalence de SCP et SARM sur carcasses en fin de chaîne d’abattage, avant réfrigération dans 4 abattoirs afin de consolider les résultats obtenus dans un seul abattoir.
Il visait également à caractériser les souches de SCP isolées pour : (1) leur appartenance à l’espèce S. aureus et (2) leur capacité de production d’entérotoxines, afin de confirmer le risque d’intoxination lié à la présence de Staphylococcus aureus d’origine porcine.

PDF icon Carole Feurer, bilan 2017, éditions IFIP, mai 2018, p. 82-83, fiche n° 45
2018

Impact de sel nitrité ou de bouillon de nitrate fermenté sur la croissance de germes dans le jambon cuit

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Bastien Frémaux, bilan 2017, éditions IFIP, mai 2018, p. 78

Le nitrite en tant qu’additif, contribue à la sécurité microbiologique, à la saveur, la couleur et à la stabilité antioxydative des produits à base de viande. Pour certaines charcuteries vulnérables sur le plan microbiologique comme le jambon cuit, son utilisation combinée à celle du sel (chlorure de sodium, NaCl) permet de garantir un niveau de sécurité suffisant, notamment vis-à-vis de C. botulinum. Deux procédés sont aujourd’hui employés pour incorporer du nitrite dans le jambon cuit. Il peut être introduit directement dans la saumure sous forme de sel nitrité (sel ordinaire + nitrite de sodium NaNO2, E250 ou de potassium KNO2, E249) ou généré en cours de procédé à partir de nitrate d’un bouillon de légumes fermenté par une flore technologique inoculée volontairement.
Cette étude visait à caractériser les fonctionnalités de conservation et sensorielle du nitrite d’origine fermentaire en comparaison au sel nitrité. Pour cela, différentes teneurs en nitrite et en NaCl ont été combinées, et leurs impacts étudiés vis-à-vis du devenir de germes d’intérêt (pathogène ou d’altération) durant la fabrication et la conservation du jambon cuit. Une analyse sensorielle des jambons issus des différentes formulations a en parallèle été réalisée par un panel d’experts IFIP.

PDF icon Bastien Frémaux, bilan 2017, éditions IFIP, mai 2018, p. 78, fiche n° 41
2018

Développement d’une méthode alternative de quantifi cation de Pseudomonas par PCR quantitative dans les produits carnés

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Bastien Frémaux, bilan 2017, éditions IFIP, mai 2018, p. 40

Les Pseudomonas sont les principales bactéries psychrotrophes retrouvées sur les carcasses après refroidissement. La réfrigération permet leur multiplication et la production d’enzymes protéolytiques et lipolytiques responsables d’altérations (rancissement, putréfaction). Pseudomonas est principalement utilisée comme indicateur d’altération des viandes fraîches ou d’un défaut de conditionnement.
La FCD impose des critères microbiologiques relatifs aux Pseudomonas pour certains produits à la distribution, dont les pièces de découpe réfrigérées porcines, les viandes piécées de porc ou les saucisses à cuire. La méthode de référence NF EN ISO 13720 relative au dénombrement de Pseudomonas dans les viandes et produits à base de viande repose sur l’utilisation de la gélose sélective CFC (cétrimide, fucidine, céphaloridine). Sa sélectivité est toutefois controversée ; des essais antérieurs réalisés par l’IFIP ayant montré que jusqu’à 40% des colonies caractéristiques isolées sur CFC sont en fait des entérobactéries, surévaluant ainsi la concentration réelle de Pseudomonas dans les produits analysés. Cette étude visait à développer une méthode de dénombrement des Pseudomonas, alternative à la norme NF EN ISO 13720 par PCR quantitative, afin de proposer aux professionnels une méthode plus robuste. Ses performances ont été confrontées à celles de la norme NF EN ISO 13720 et celles de la méthode RHAPSODY Agar® validée en 2015 par l’AFNOR (validation NF) pour le dénombrement des Pseudomonas dans les produits carnés et les produits laitiers.

PDF icon Bastien Frémaux, bilan 2017, éditions IFIP, mai 2018, p. 40, fiche n° 12
2018

Polyphyletic nature of Salmonella enterica serotype Derby and lineage-specific host-association revealed by genome-wide analysi

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Yann Sévellec (Anses) et al., Frontiers in Microbiology, 2018, 17 mai, 13 pages

In France, Salmonella Derby is one of the most prevalent serotypes in pork and poultry meat. Since 2006, it has ranked among the 10 most frequent Salmonella serotypes isolated in humans. In previous publications, Salmonella Derby isolates have been characterized by pulsed field gel electrophoresis (PFGE) and antimicrobial resistance (AMR) profiles revealing the existence of different pulsotypes and AMR phenotypic groups. However, these results suffer from the low discriminatory power of these typing methods. In the present study, we built a collection of 140 strains of S. Derby collected in France from 2014 to 2015 representative of the pork and poultry food sectors. The whole collection was characterized using whole genome sequencing (WGS), providing a significant contribution to the knowledge of this underrepresented serotype, with few genomes available in public databases. The genetic diversity of the S.Derby strains was analyzed by single-nucleotide polymorphism (SNP). We also investigated AMR by both genome and phenotype, the main Salmonella pathogenicity island (SPI) and the fimH gene sequences. Our results show that this S. Derby collection is spread across four different lineages genetically distant by an average of 15k SNPs. These lineages correspond to four multilocus sequence typing (MLST) types (ST39, ST40, ST71, and ST682), which were found to be associated with specific animal hosts: pork and poultry. While the ST71 and ST682 strains are pansusceptible, ST40 isolates are characterized by the multidrug resistant profile STR-SSS-TET. Considering virulence determinants, only ST39 and ST40 present the SPI-23, which has previously been associated with pork enterocyte invasion. Furthermore, the pork ST682 isolates were found to carry mutations in the fimH sequence that could participate in the host tropism of this group. Our phylogenetic analysis demonstrates the polyphyletic nature of the Salmonella serotype Derby and provides an opportunity to identify genetic factors associated with host adaptation and markers for the monitoring of these different lineages within the corresponding animal sectors. The recognition of these four lineages is of primary importance for epidemiological surveillance throughout the food production chains and constitutes the first step toward refining monitoring and preventing dispersal of this pathogen.

https://www.frontiersin.org/articles/10.3389/fmicb.2018.00891/pdf

2018

Genomic diversity of Salmonella Derby populations from animals to humans: study on source attribution and identification of specific host associations

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Yann Sévellec et al., Congrès international, IAFP, 25-27 avril 2018, Stockholm, Suède, poster

In the European Union (EU), Salmonella enterica subsp. enterica serotype Derby (S. Derby) is the most abundant serotype isolated from pork meat. In France this pathogen is mainly isolated from pork and poultry meat and ranks since 2000 between the 5th and 8th position of the most frequently isolated serotypes in humans. Despite significant threat to human health, few studies have focused on the genetic diversity of this pathogen and all suffer from the low discriminatory power of the sub-typing method used or the lack of strains.

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2018

RedLosses: REDucing food LOSSES by microbial spoilage prediction

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Monique Zagorec et al., 3rd International Symposium on Fermented Meat (ISM), Clermont-Ferrand, 27-29 septembre 2017, poster

Food spoilage leads to significant wastes and losses, and is an important economic issue in food industry. In the case of meat, a large part of spoilage is the consequence of bacterial growth and subsequent metabolic activities causing organoleptic spoilage of the final product (defects in texture, color, odor, or aspect), leading finally to products that are lost because they do not fit the quality standards. In addition, meat production chain requires energy, water and cost consuming operations (i.e. animal breeding, slaughtering, and transformation and storage which are usually performed at low temperature). Therefore meat product spoilage that appears at the end of the process or during shelf life affects the whole production chain performances as well as the sustainability label of the meat sector. The objective of the project is to reduce food losses by predicting, early in the production process, the onset of bacterial spoilage during storage in order to propose decision-support tools for directing process. Pork and poultry meat, the two main meats consumed in France will be studied. The economic impact of losses of these products will be assessed. Dynamics of bacterial communities will be monitored during processing steps (from primary cuts to end products at use-by-date and beyond) and various descriptors of spoilage will be measured. The natural variability between batches and that associated with production processes will be considered. Data will be used to identify accurate spoilage markers and to compute innovative mathematical models for predicting spoilage occurrence as a function of the initial composition of the microbiota (diversity and abundance) and some abiotic factors (lactate concentration, modified atmosphere packaging). The models will be validated on meat products, including the economic aspect in order to propose decision-support tools for the food producers. The project involves 8 academic or ITAI partners constituting the REDLOSSES consortium and 2 industrial partners producing sausages.

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2017

In vitro characterization of the ability of Yersinia enterocolitica BT4 to colonize pigs and stainless steel surfaces

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Pierre Raymond et al., 12th SAFEPORK, 21-24 août 2017, Foz do Iguassu, Brésil, poster

Y. enterocolitica is the third bacterial cause of human enteritis in Europe (1). The biotype 4 (BT4) is the biotype the most frequently isolated from both pigs and clinical yersiniosis (2, 3). The ability of BT4 strains to infect humans may depend on their capability to colonize pigs and to develop biofilm on conventional materials used in food industries.
This study investigated the use of two in vitro tests to assess the ability of BT4 strains, to adhere and invade intestinal pig cells (IPEC-J2) and to adhere to stainless steel surfaces.

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2017

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