Bacteriophages as biocontrol tools of pathogens in meat and dairy products

Abstract

Biocontrol by bacteriophages in meat and dairy products was developed in the last years and their recent ´generally recognized as safe´ (GRAS) designation and approval as food additives (FDA, 2006) has opened the discussion about edible virus. The phage treatment can be applied at different stages in the food chain production, from the live animal to the manufactured product. In this chapter we focus on their application during milk and raw meat processing prior to consumption in order to extend the shelf life of these perishable foods. Studies using bacteriophages as biocontrol tools in meat products have focused particularly on Escherichia coli O157:H7, but other pathogens such as Campylobacter jejuni, Listeria monocytogenes and Salmonella enterica have also received attention. Even though the major concern in dairy production is preventing phage infection of dairy starter cultures, the aim of this chapter is to address the use of bacteriophages for biocontrol of pathogens like Staphylococcus aureus, Escherichia coli, Enterobacter sakazakii, Listeria monocytogenes, Mycobacterium smegmatis and Salmonella enteritidis. On the other hand, a section will be dedicated to revise the biocontrol of Shiga-toxigenic Escherichia coli (STEC) pathogens in meat and dairy foods. STEC is the etiologic agent of hemolytic uremic syndrome (HUS), a disease endemic in countries like Argentine, which has the highest incidence worldwide with 13.9 cases per 100,000 children under 5 years of age. In spite of the advantages of the use of bacteriophages in food safety, a drawback is the emergence of bacteriophage insensitive mutants (BIMs). Nevertheless, low frequency of emergence, phenotype reversions and variable stability of BIMs were reported to date. Furthermore, phage cocktails can be used to counteract the effect of BIMs occurrence.