How Should Staphylococcal Food Poisoning Outbreaks Be Characterized?

Staphylococcal food poisoning is one of the most common food-borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All SEs have superantigenic activity whereas only a few have been proved to be emetic, representing a potential hazard for consumers. Characterization of staphylococcal food poisoning outbreaks (SFPOs) has considerably progressed compared to 80 years ago, when staphylococci were simply enumerated and only five enterotoxins were known for qualitative detection. Today, SFPOs can be characterized by a number of approaches, such as the identification of S. aureus biovars, PCR and RT-PCR methods to identify the se genes involved, immunodetection of specific SEs, and absolute quantification by mass spectrometry. An integrated gene-to-protein approach for characterizing staphylococcal food poisoning is advocated

How does a mouse increase its velocity? A model for investigation in the control of locomotion

We analysed treadmill locomotion of the adult SWISS-OF1 mice over a large range of velocities. The use of a high-speed video camera combined with cinefluoroscopic equipment allowed us to quantify in detail the various space and time parameters of limb kinematics. We find that velocity adjustments depend upon whether animal used a symmetrical or non-symmetrical gait. In symmetrical gaits, the increase of velocity generally results equally from an increase in the stride frequency and the stride length. On the other hand, in non-symmetrical gaits, the increase in velocity is achieved differently according to the level of velocity used. As speed increases, velocity increases first as a consequence of increased stride frequency, then as in symmetrical gaits, by an equal increase in both variables, and finally at high speed, velocity increases through increased stride length. In both symmetrical and non-symmetrical gaits, stance and swing-time shortening contributed to the increase of the stride frequency, with stance time decrease being the major contributor. The pattern of locomotion obtained in the present study may be used as a model mouse system for studying locomotor deficits resulting from specific mutations in the nervous system

Gait parameters of treadmill versus overground locomotion in mouse

International audienc

Capteurs pour la surveillance de la qualité de l'air ambiant extérieur : Enseignements et résultats du premier essai national d'aptitudes des micro-capteurs

International audienc

Organization and ELISA-Based Results of the First Proficiency Testing to Evaluate the Ability of European Union Laboratories to Detect Staphylococcal Enterotoxin Type B (SEB) in Buffer and Milk

The aim of this work was to organize the first proficiency test (PT) dedicated to staphylococcal enterotoxin B (SEB) detection in milk and buffer solutions. This paper describes the organization of the PT trial according to EN ISO 17043 requirements. Characterization of the SEB stock solution was performed using SDS-PAGE and SE-specific ELISA, and amino acid analysis was used to assign its protein concentration. The solution was then used to prepare six PT materials (four milk and two buffer batches) at a ng/g toxin level, which included one blank and one SEA-containing milk as specificity control. Suitable material homogeneity and stability were assessed using screening and quantitative ELISAs. Among the methods used by the participants, ELISA-based methods demonstrated their efficiency for the detection of SEB in both simple and complex matrices. The results serve as a basis for further improving the detection capabilities in expert laboratories and can therefore be considered as a contribution to biopreparedness

The cytotoxic potential of Bacillus cereus strains of various origins

https://doi.org/10.1016/j.fm.2021.103759 B. cereus is a human pathogen associated with food poisoning leading to gastrointestinal disorders, as well as local and severe systemic infections. The pathogenic spectrum of B. cereus ranges from strains used as probiotics in humans to lethal highly toxic strains. In this study, we gathered a collection of 100 strains representative of the pathological diversity of B. cereus in humans, and characterized these strains for their cytotoxic potential towards human cells. We analyzed the correlation between cytotoxicity to epithelial and macrophage cells and the combination of 10 genes suspected to play a role during B. cereus virulence. We highlight genetic differences among isolates and studied correlations between genetic signature, cytotoxicity and strain pathological status. We hope that our findings will improve our understanding of the pathogenicity of B. cereus, thereby making it possible to improve both clinical diagnosis and food safety

: Travaux LCSQA 2017 (Convention n°2201070603)

Note technique rendant compte de l’opportunité d’établir un protocole pour la caractérisation métrologique en laboratoire de micro-capteurs pour la mesure indicative des particules (au sens de la Directive européenne "Qualité de l'air 2008/50/CE")