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Working Group 5: Environmental lifestyle and persistence of food – borne pathogens

WG Leader: Hanne Ingmer, KU, Denmark

Members: Kieran Jordan, TEAGASC, Ireland; Martin Wager, vetmeduni, Austria; Jürgen Zentek, Anneluise Mader, FUB, Germany; Peter Raspor, Sonja Smole-Mozina, UNI-LJ, Slovenia; John Wallace, UNIABDN, UK; Hanna-Leena Alakomi, VTT, Finland.

Research topics for the future:

Role of persistent /re-occurring bacteria in food safety. Bacteria persist in the food chain and this persistence result in contamination of production animals and of raw materials and processed food. In some cases the exact same bacteria/clone can be identified with years in between suggesting that this specific type or clone of bacteria survive on the farm or in the feed and food processing environment despite cleaning and disinfection. In other cases the pathogens survive in the external environment and are re-introduced into the food chain. More knowledge is needed to understand how bacteria behave in the food chain and the mechanisms behind some bacteria´s ability to survive in often harsh conditions for years.

Prevention of contamination and reduction of the levels of pathogens (persistent and re-occuring) in the food chain. Identification of the main sources for pathogen re-introduction into the food chain is highly important in order to reduce the prevalence. However, pathogens will occur in animals and strategies on how to reduce levels of colonization and cross contamination within herds/flock is very important. However, in many cases the role of the different factors is not fully understood. In primary production we need more knowledge on 1) the level of contamination with pathogens in feed (e.g. commercial versus self mixed feed) 2) the importance of different factors that favour the spread of pathogens and factors that seems to decrease the risk of pathogen colonization such as the efficacy of feed additives (different organic acids, essentiel oils, fermentable carbohydrates etc.) on reducing intestinal numbers of pathogens, 3) Role of the intestinal microbiota for prevention of colonization with pathogens and whether it is possible to manipulate the microbiota to reduce colonization with pathogens like Salmonella, VTEC, and Campylobacter.

In the secondary production / food and feed processing environment, we need a better understanding of 1) How to prevent biofilm formation (antibacterial surfaces, antifouling layers), 2) The role of multispecies biofilms and microbial communities in field conditions for persistence, 3) The impact of targeted hygiene, cleaning and disinfection strategies 4) Identification of critical sites for re-contamination/survival of pathogens and for this fast and reliable detection and characterization methods. Finally, new technologies to reduce pathogen load is also needed including knowledge on the use of bacteriophages to control pathogens in raw materials and food and in the processing environment.

The effects of interventions along the food chain on human health: Many of the human cases of food borne infections are zoonotic and several initiatives are discussed in order to break the chain of infection and reduce the number of zoonotic infections in humans such as Salmonellosis and Campylobacteriosis. These includes interventions at farm level, at slaughter houses and processing plants and at the consumers such as 1) reduction of the flock/herd prevalence of pathogens; 2) reduced shedding/prevalence of persistent bacteria; 3) reduction of the number of eg Salmonella and/or Campylobacter on the animal/carcasses/raw meat; 4) reduction of cross-contamination from pathogen positive to pathogen negative flocks/herds during slaughter; and 5) reduction of the occurrence of cross-contamination during food handling. Estimates of the influence of different mitigation strategies are needed in order to find (the most) effective, robust and cheap solutions.

Fast and reliable detection and characterization of pathogens in the food chain. In order to intervene it is necessary to have updated knowledge on source attributions to human infections. In recent years we have seen infections with eg. Salmonella from sources that were no previously associated with Salmonella such a vegetables and food products with low water activity. In contrast to many food products of animal origin and faecal samples, the levels of pathogens in these products are often very low but the infective dose of the pathogen is also estimated to be as low as <100 CFU when originating from such dry products. The likelihood of detecting Salmonella in some of these product including many dry feed and food product as well in certain processing environments could be very low as the role of some feed/food matrixes for detection probability of pathogens in all relevant products is not fully understood. Also the role of non culturable bacteria in this area needs further investigation. Furthermore, in order to track and trace pathogens in the food chain e.g. after an outbreak it is necessary to characterize these isolates. An important topic is thus development and implementation of new technologies for a more fast and precise monitoring/traceability and characterization of pathogens (incl “new” pathogens as well as new combinations of pathogen/food) and their potential in the food chain (various matrices).

Relevant publication of the Group:

Title (and if available Link): Persistence of foodborne pathogens and their control in primary and secondary food production chains;

Please note access to the full text of this article will depend on personal or institutional entitlements; Authors: Marianne Halberg Larsen, Marion Dalmasso, Hanne Ingmer, Solveig Langsrud, Mindaugas Malakauskas, Anneluise Mader, Trond Møretrø, Sonja Smole Možina , Kathrin Rychli, Martin Wagner, R. John Wallace, Jurgen Zentek and Kieran Jordan. Title/No. of periodical: Food control vol. 44 page 92-109, Year of publication: 2014

The article´s essential statements: The review highlights factors involved in the persistence of foodborne pathogens in selected food chains and covers aspects of the basis for persistence, the consequences of persistence in terms of food safety implications, and the strategies that can be employed to combat persistence. The examples selected are Escherichia coli O157 and Salmonella at primary production of cattle and pigs, respectively, Listeria monocytogenes and Cronobacter spp. at secondary production, while persistence of Campylobacter spp. represents both primary and secondary production.