Antimicrobial Resistance of Fermented Food Bacteria

Abstract

Lactic acid bacteria (LAB) are the most important bacterial group involved in fermented food production. Some fermented products include additional microbiological groups important for products’ safety and quality such as coagulase- negative staphylococci (CoNS), yeasts and molds. CoNS and molds are particularly important in fermented meat products, by contributing to proteolytic and lipolytic succession. Yeasts are more employed in cheese and fermented milks production. Some species or strains have been selected as technologically or hygienically superior to others, leading to raw materials inoculation (e.g. milk, sausage mixture). Results of their activity during the production phase (or shelf- life) should be the final products with desirable sensorial features and/or lower microbial health hazards. Such kind of microbial species or strains are known as (protective) starter cultures which are recognized as safe in fermented food production. Recently, a great research expansion was done in the area of autochthonous starter cultures, i.e. the potential application of strains isolated from traditionally fermented foodstuffs into industrial conditions. The purpose of that approach is to produce industrial food product with autochthonous sensorial features, with the help of wild strain(s). Selection of potential starter cultures should include health-hazard testing, such as possibility of strains to produce biogenic amines, toxins or antibiotic resistance gene carriage. Today hundreds of substances are currently used as active principles in health products developed for the treatment of food producing animals.According to this many animals are exposed to chemicals that may leave residues in the carcass at the time of slaughter. The possibility of resistant organisms of animal origin becoming directly pathogenic to man, or transferring their resistance genes to pathogens of medical importance, is of particular concern. Due to the intensive use of antibiotics in public health and animal husbandry, antibiotic resistance in pathogens has been an increasing medical problem during the last decades. The prudent use of antibiotics in veterinary medicine and agriculture is an important factor of spreading antimicrobial resistance through food production chain. In addition to spread of resistant zoonotic foodborne pathogens, there is also possibility that food-related commensal bacteria or opportunistic pathogens are carriers of resistance genes and therefore a potential hazard to consumers. Fermented food products could be an ideal vehicle for antimicrobial resistance transfer from animals, environment or humans through food chain, because these products are not thermally treated and are naturally rich in indigenous microbiota. During last decades the hazard potential of natural microbiota from fermented food was assessing in relation to potential hazards, including antimicrobial resistance. In general, low occurrence of hazards determinants was found in food CoNS and LAB, but the presence of resistance genes is still the reason for concern.Antimicrobial resistance is basically most important in clinically relevant zoonotic bacteria, since directly threatened human life. The significance of antimicrobial resistance in food-borne non-pathogens is not recognized as rising public health problem, but theoretically could be taken into account as potential threat. In this respect, naturally present LAB or CoNS in different fermented food can be observed as potentially hazardous microbial groups as transmitters of antibiotic resistance determinants. In present chapter the antimicrobial resistance of CoNS and LAB (enterococci) is discussed, in terms of fermented meat/milk products and raw materials.