Incidence, prevalence and detection of pathongens through fast techniques in the meat indutstry and RTE meat products

The present proposal intends to make a contribution to the improvement of RTE  meat products safety by analyzing the incidence and prevalence of Listeria monocytogenes, Salmonella, E. coli O157:H7, Y. enterocolítica, Aeromonas, and Campylobacter in the meat industry. The concern for the prevalence and incidence of these microorganisms in the meat industry is quite understandable (Jacobsen and Koch, 2006).

The need for fast pathogen-detecting methods of the above microorganisms has already been stated. The most promising method is that of PCR. The adaptation of PCR systems to real time and final time for detecting and identifying pathogens in RTE products will be tested in order to determine its sensitivity, specificity and profitability. Up to now, the use of PCR as a fast technique for food pathogen detection has not been widespread given the lack of protocols validated and standardized by the CEN (European Committee for Standardization). In this context, the EU has financed a project (V Frame program, “FOOD-PCR”) for developing and validating standardized PCR protocols for pathogens detection (Salmonella, E. coli O157:H7 L. monocytogenes, Y. enterocolítica, Campylobacter). The study of PCR application in real time for detecting and identifying some pathogenic microorganisms in food from pure cultures are already under way (Rodríguez-Lázaro et al., 2003; 2004; 2005). This project intends to use the experience of the group led by Aymerich in the application of PCR methods developed for detecting pathogens in RTE food. The development of a mixed system for detecting Salmonella and L. monocytogenes simultaneously will be researched.

But not only these microorganisms are relevant for RTE products. A variety of species of staphylococci and moulds such as the prevailing microorganisms during the maturing process of raw meat and different types of raw cured meat products have been recorded (Núñez et al., 1996; Lizaso et al., 1999; Kitai et al., 2005). Among these microorganisms some toxigenic species have been found. In this way, staphylococci that produce enterotoxin have been isolated in cured ham and raw-matured cold meats and the production of enterotoxins in meat products have been proved (Portacarrero et al., 2002). At the same time, most mould species found in raw cured meat products can synthesize mycotoxins such as cyclopiazonic acid, ochratoxin A, sterigmatocystin and citrinine, verrucosidin, aflatoxin B and patulin when they grow under conditions present in the ripening process (Núñez et al., 1996; Sosa et al., 2002). Thus, there is an urge for developing fast methods to detect  toxigenic microorganisms (Staphylococcus spp. that produces enterotoxins and moulds that produce mycotoxins). This is one of the goals of this subproject.

Finally, this subproject will also tackle the detection and quantification of enteric viruses in food through similar techniques. Available data on the incidence of food-borne infections of viral origin is limited. This partially results from the absence of laboratories with appropriate equipment to investigate the presence of viruses in food and confirm the viral aetiology of the outbreak because this methodology has been complex and non-standardized. Moreover, protocols used to extract viruses from food are not contrasted and standardized enough and are characterized by a very low and variable recovery rate (2-53%). Thanks to molecular biology breakthroughs, new analytical techniques applicable to virus detection on food have come up in the past years. These techniques are based on the hybridization of the nucleic acid with a DNA or RNA probe, and on polymerase chain reaction (PCR). This research intends to come up with a fast, sensitive, robust and specific analytical methodology to detect and quantify –through end time PCR and real time PCR- the RNA virus of interest as to food safety, responsible for enteric, non bacterial infections (Hepatitis A virus, rotavirus, and Norwalk virus) present in meat products. It also intends to evaluate the incidence of such viruses in meat products

Instituto de Recerca I Tecnologia Agroalimentaria (IRTA)

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