Search

International audience; The rise of antibiotic resistance is not only a challenge for human and animal health treatments, but is also posing the risk of spreading among bacterial populations in foodstuffs. Farmed fish-related foodstuffs, the food of animal origin most consumed worldwide, are suspected to be a reservoir of antibiotic resistance genes and resistant bacterial hazards. However, scant research has been devoted to the possible sources of diversity in fresh fillet bacterial ecosystems (farm environment including rivers and practices, and factory environment). In this study bacterial communities and the antibiotic resistance genes of fresh rainbow trout fillet were described using amplicon sequencing of the V3-V4 region of the 16S rRNA gene and high-throughput qPCR assay. The antibiotic residues were quantified using liquid chromatography/mass spectrometry methods. A total of 56 fillets (composed of muscle and skin tissue) from fish raised on two farms on the same river were collected and processed under either factory or laboratory sterile filleting conditions. We observed a core-bacterial community profile on the fresh rainbow trout fillets, but the processing conditions of the fillets has a great influence on their mean bacterial load (3.38 ± 1.01 log CFU/g vs 2.29 ± 0.72 log CFU/g) and on the inter-individual diversity of the bacterial community. The bacterial communities were dominated by Gamma- and Alpha-proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. The most prevalent genera were Pseudomonas, Escherichia-Shigella, Chryseobacterium, and Carnobacterium. Of the 73 antibiotic residues searched, only oxytetracycline residues were detected in 13/56 fillets, all below the European Union maximum residue limit (6.40-40.20 μg/kg). Of the 248 antibiotic resistance genes searched, 11 were found to be present in at least 20% of the fish population (tetracycline resistance genes tetM and tetV, β-lactam resistance genes bla (DHA) and bla (ACC), macrolide resistance gene mphA, vancomycin resistance genes vanTG and vanWG and multidrug-resistance genes mdtE, mexF, vgaB and msrA) at relatively low abundances calculated proportionally to the 16S rRNA gene.

National audience; The role of food in the routes of transmission of resistant bacteria and antimicrobial resistance genes (ARG) is yet to be explored. Farmed fish filets can carry antibiotic-resistant bacteria because of their environmental exposure (animal farms, human activities, aquatic environment…). The presence of such bacteria on foodstuff must be evaluated as it might present a risk for the consumers. To extend our knowledge about the farmed fish filet resistome, ARG were sought in the bacterial communities of fresh rainbow-trout filets. Antimicrobial residues were also dosed in the filets. The analyses were performed on fishes originating from a single batch sampled in two conditions: a) filets excised in laboratory conditions (N = 14) and b) filets excised in an industrial facility (N = 14). Each filet was divided, one sample was rinsed and the DNA was extracted to perform the ARG investigation and one sample was analysed to perform the antimicrobial residues dosing. Insights about events occurring during the lifetime of the fishes, such as diseases, treatments, vaccines and pond cleaning frequency were provided by the breeders. The ARG were detected and quantified using a 245 primers pairs set. The set were chosen after bibliography analyses [1] and in silico verification. It was designed to detect resistances to 10 antimicrobial classes, including beta lactams, macrolides, tetracyclines, aminoglycosides, phenicols, as well as multidrug efflux pumps and biocides resistance genes. The amplification was realised thanks to the Smartchip Real-Time PCR technology (Takara). The residues of 75 antimicrobials, covering 10 antimicrobial classes, were looked for and quantified by LC-MS/MS. Some ARG were detected at Ct around 25 (tetL, tetB, sul1), as well as biocide resistance genes (qacEΔ1). Oxytetracycline residues were detected in 13 filets (out of 28) in concentrations lower than the authorized maximum residue limit. The concentrations ranged from 5,84 to 40,2 μg/kg and the authorized maximum residue limit is 100 μg/kg in the fish muscle. Fishes were treated with oxytetracycline more than 6 months before the sampling. Overall, few antimicrobial resistance genes were detected and the detected genes displayed high Ct, suggesting that this genes had low prevalence in the bacterial communities. Presence of tetracycline resistance genes and oxytetracycline residues have been observed in fish samples from a batch where an oxytetracycline treatment has been applied. No correlation has been established yet. Further investigations are necessary in order to understand the links between the presence of residues and genes, and the phenotypic resistances

International audience; RATIONALE: This paper investigates the validity of the transfer of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the determination of veterinary medicinal products in honey and compares it with an LC/linear ion trap/Orbitrap mass spectrometry method. A descriptive statistical approach was used in order to assess whether such a transfer would succeed or fail. This approach is based on the simultaneous evaluation of the trueness and of the intermediate precision for each compound at a 95% interval of confidence of both analytical techniques. METHODS: Two grams of honey were placed in a centrifuge tube and diluted with 2.5 mL of ultra-pure water and 2.5 mL of acidified methanol with hydrochloric acid at 2 mol.mL-1 . The extract was purified with 50 mg of primary secondary amine and then analyzed using LC/MS/MS in multiple reaction monitoring (MRM) mode and LC/orbitrap high-resolution mass spectrometry in full scan mode. Both analytical techniques were compared by using the descriptive statistical approach for the determination of antimicrobial residues in honey. RESULTS: The transfer of the method showed that the Orbitrap system provides the same accurate analytical results compared with the LC/MS/MS method except for 4-epitetracycline, anhydroerythromycin A, erythromycin A enol ether, and dihydrostreptomycin. Furthermore, the LC/LTQ-Orbitrap system is capable of successfully competing with the LC/MS/MS method by additional provision of high mass resolution and mass accuracy even though it shows less sensitivity compared with the LC/MS/MS instrument. CCalpha levels for most analytes were 1.3 times higher by LC/MS/MS than those observed by LC/LTQ-Orbitrap. The method was assessed in terms of relative bias through analysis of a reference material provided by FAPAS (Food Analysis Performance and Assessment Scheme) and also through the control of several contaminated honey samples from local Lebanese markets. Satisfactory relative bias was below 22% except for tetracycline found in one sample that showed a higher bias at 29%. CONCLUSIONS: The LC/LTQ-Orbitrap method offers adequate performance in comparison with previously validated method on a LC/MS/MS system resulting in acceptance of the transfer of the method from LC/MS/MS to LC/LTQ-Orbitrap.

International audience; Pour la recherche de résidus antibiotiques dans la viande bovine, par exemple, des méthodes de chromatographie liquide couplée à la spectrométrie sont désormais validées et utilisées en France, permettant de détecter rapidement plus de 60 antibiotiques. Sont ciblées les carcasses “anormales” ou qui font l’objet d’informations suspectes sur le document d’accompagnement.La filière bovine française a obtenu des résultats très encourageants sur les échantillons de 2013 (les résultats 2016 sont en cours d’analyse). Le non-respect des temps d’attente ou de la prescription, chez les vaches de réforme et les veaux, est principalement en cause pour les résidus dans la viande bovine. Des progrès semblent encore possibles.

International audience; Antibiotiques et biocides désinfectants de l’eau font-ils toujours bon ménage ?