Detecting pathogens in seafood

The food of choice at end-of year festivities and wedding breakfasts, seafood is an integral part of festive occasions. But in order to ensure that the party does not end badly, the quality and freshness of this tempting food must be guaranteed. Indeed, seafood can be a carrier of different pathogenic microorganisms. In Europe, the marketing of seafood is fortunately well controlled in order to minimize health risks to consumers. Georges Daube and his team at the Food Microbiology Laboratory of the University of Liege have developed a method of molecular biology which makes it possible to amplify specific genes of microorganisms in order not only to detect pathogens, but also to estimate their quantity.

HuitresFrom 1995 to 2009, the Food Microbiology Laboratory of the University of Liege, directed by Professor Georges Daube, has been the stand out laboratory in this area as far as the ministry of public health is concerned. "In this context, a large part of our activities consisted of managing approved laboratories but also to develop and validate efficient methods for assessing and managing the microbiological quality of food at a national level", explains Georges Daube, of the Food Science Department of the Faculty of Veterinary Medicine of the University of Liege. "We were more particularly specialized in the bacterial and virological examination of live bivalve molluscs", explains the Professor.

Oysters, mussels and other shellfish are particularly problematic from a food hygiene point of view because these organisms filter large quantities of water in order to feed. Particles suspended in the water carry bacteria and viruses, which come from human or animal feces and which are then concentrated in molluscs. "The role of our laboratory was to perfect methods for detecting these types of pathogens", continues the researcher.

Developing an efficient method for the AFSCA

Apart from the “filtering” activity of bivalve molluscs, the way we eat them, either raw or lightly cooked, represents an extra health risk. While oysters do not generally make it to the saucepan, the cooking of mussels and shellfish stops as soon as the bivalves open. "They are therefore not subjected to temperatures that are high enough to remove the microorganisms present in the water ", continues Georges Daube. " And as far as crustaceans are concerned, there are often cases or recontamination after cooking, when they are de-shelled for example. The bacteria and viruses present on the hands or on the raw shrimps handled just before can also make their way to our plates as well".

Although there is only one producer of oysters and one producer of mussels in Belgium, we consume seafood from France, Spain and other neighboring or other overseas countries. In order to ensure the safety of Belgian consumers, the Ministry of Health, and more particularly, the Federal Agency for Safety of the Food Chain (FASFC), needs efficient methods for carrying out these checks. This is exactly what Georges Daube and his colleagues suggest in a recent study published in Food Control (1). "At the beginning of the 2000s, we only had rudimentary methods for detecting the presence of microorganisms in food", indicates the scientist. "It was necessary to crush the food, place it in solution, and isolate the microorganisms by placing them in Petri dish cultures in order to allow them to multiply. These methods were very laborious".

(1) B. Taminiau, N. Korsak, C. Lemaire, V. Delcenserie, G. Daube. Validation of real-time PCR for detection of six major pathogens in seafood products. Food Control. Volume 44, October 2014, Pages 130–137

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