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More than 5000 food-borne outbreaks (FBOs) are reported annually in the EU (EFSA), with bacterial toxins ranking at the third position (850 outbreaks, 16.5%). These include toxins produced by Staphylococcus spp., Bacillus spp. and Clostridium spp. In 2014, 393 FBOs (7.5%) were caused by staphylococcal toxins and 287 (5.5%) by Bacillus toxins. Clostridium toxins accounted for 160 (3.1%) outbreaks, including 124 by C. perfringens, 9 by C. botulinum and 27 by unspecified Clostridia. Overall, 9368 human cases, 592 hospitalizations and 5 deaths caused by bacterial toxins were reported in the EU in 2014.

Staphylococcal food poisoning (SFP) are characterized by nausea followed by incoercible vomiting caused by the ingestion of food contaminated by staphylococcal enterotoxins (SEs) produced by enterotoxigenic strains of coagulase-positive staphylococci (CPS), mainly S. aureus. Detection and quantification of SEs in food remnants remains a real challenge. The available immunoenzymatic methods do not cover the entire spectrum of SEs as only five SE serotypes out of 22 SE types are currently detectable. Epidemiological data indicate that there is an increase of cases caused by emerging S. aureus strains producing other types of toxins. Given the lack of method covering all SE types, the EU reference laboratory for CPS is frequently confronted with SFPs that remain unsolved for the majority of them. B. cereus may cause an emetic or a diarrheal-type of food-borne illness. Although these two types of symptomatology are generally mild and self-limiting, more serious and even lethal cases have been described. Emetic strains can be readily detected due to the presence of the ces gene. Nevertheless, for most of diarrheal diseases, factors leading to diarrheal pathogenicity remain unclear and there is no available method to distinguish pathogenic B. cereus from non-pathogenic strains. C. perfringens may cause gastrointestinal disease, gas gangrene and related necrotic conditions in humans and other mammals. Gastroenteritis is characterized by mild and self-limiting symptoms, including watery diarrhea and mild abdominal cramps, caused by the production of C. perfringens enterotoxin (CPE) encoded. Recently, genome analysis has identified additional genes encoding potential toxins for which no functional data are available and their role in gastroenteritis is unknown.

OBJECTIVES

The aim of this project is to develop and harmonize new (“non-NGS”) methods for a better detection and quantification of bacterial toxins or factors involved in the virulence, including those that remain currently undetectable. Mass spectrometry based methods such as LC-MS/MS will be considered as a relevant choice as this type of method is known to be highly specific and possibly quantitative. Other mass spectrometry method (MALDI-ToF) should also be useful as an alternative tool to NGS for rapid identification of toxigenic bacteria including non-classical or emerging strains. This project will cover all the steps of the analysis, from sample preparation to analytical results. Rapid methods allowing the analysis of toxin gene expression will also be developed and harmonized as complementary tools to provide essential information on the toxigenic potential of bacterial strains. Finally, proficiency tests will be organized to assess the performance of the developed methods. With this project, the partners will be able to harmonize MS-based methods which are currently under development in their laboratories. Reference laboratories with high expertise in FBO investigations are included among the participants which will be an asset to this project. This project will ultimately lead to an increased proportion of “strong evidence” outbreaks versus “weak evidence” outbreaks and therefore to a better investigation of FBOs caused by toxigenic bacteria.

PARTNERS

• ANSES Maisons-Alfort (France) : Drs Jacques-Antoine Hennekinne et Yacine Nia
• WIP-ISP (France) : Dr Julien Masquelier
• BfR (Allemagne) : Dr Alexandra Fetsch
• INRAE Micalis (France) : Drs Nalini Rama Rao et Michel Gohar
• IPP (France) : Drs Dominique Clermont et Julia Chamot-Rooke
• VRI (Norvège) : Drs Taran Skjerdal et Live L. Nesse

FINANCEMENT

One Health European Joint Programme JRP5-FBZ2
Grant agreement N° 773830 2018-2020