Antimicrobial resistance and the food industry

Does food serve as a source for the acquisition, by humans, of antimicrobial-resistant (AMR) bacteria or bacteria-borne antimicrobial resistance genes? The European Food Safety Authority (EFSA) posed this question to its Panel on Biological Hazards (BIOHAZ) and asked the panel to rank the identified risks and to identify potential control options for reducing exposure.

The role of food consumption and processing in human exposure to antimicrobial resistant bacteria is an emerging biological hazard caused in part by the use of antimicrobial agents throughout the food chain, from the farm to the fork according to the opinion released by the BIOHAZ Panel.

The opinion, 'Foodborne antimicrobial resistance as a biological hazard', says that the general principles on the prevention and control of the transmission of harmful bacteria to humans through food will contribute to prevent the transmission of antimicrobial-resistant bacteria by this route. These principles include the sustained practice of improved hygiene at all stages of the food chain.

The present extent of exposure to AMR bacteria was found to be difficult to determine, and the role of food in the transfer of resistance genes insufficiently studied. Nevertheless, foodborne bacteria, including known pathogens and commensal bacteria, display an increasing, extensive and diverse range of resistance to antimicrobial agents of human and veterinary importance, and any further spread of resistance among bacteria in foods is likely to have an influence on human exposure.

In all cases where antimicrobial treatment in humans is indicated, resistance to the antimicrobials of choice is of clinical importance. Resistant Salmonella and Campylobacter involved in human disease are mostly spread through foods. With regards to Salmonella, contaminated poultry meat, eggs, pork and beef are prominent in this regard. For Campylobacter, contaminated poultry meat is prominent. Cattle are a major verotoxigenic Escherichia coli (VTEC) reservoir and resistant strains may colonise humans via contaminated meat of bovine origin more commonly than from other foods. Animal-derived products remain a potential source of meticillin-resistant Staphylococcus aureus (MRSA). Food-associated MRSA, therefore, may be an emerging problem. Food is also an important source for human infections with antimicrobial-resistant Shigella spp. and Vibrio spp.

The principles that are applied to the prevention and control of the spread of pathogenic bacteria via food will also contribute to the prevention and the spread of antimicrobial-resistant pathogenic bacteria. As antimicrobial resistance in foodborne pathogens and commensals represents a specific public health hazard, additional control measures for antimicrobial-resistant bacteria may therefore be necessary. There are few examples of control programs that directly control AMR as the hazard, using measures that specifically address food. In terms of impact, controls operated at the pre-harvest phase, for example, those aimed at the control and limitation of antimicrobial usage, are potentially the most effective and as such are capable of playing a major role in reducing the occurrence of AMR bacteria in food as presented for sale.

The development and application of new approaches to the recognition and control of food as a vehicle for AMR bacteria and related genes based on epidemiological and source attribution studies directed towards fresh crop-based foods, raw poultry meat, raw pigmeat and raw beef are recommended.

Specific measures to counter the current and developing resistance of known pathogenic bacteria to fluoroquinolones as well as to third- and fourth-generation cephalosporins found in a variety of foods and in animals in primary production now require to be defined and put in place as a matter of priority.

A major source of human exposure to fluoroquinolone resistance via food appears to be poultry, whereas for cephalosporin resistance it is poultry, pork and beef that are important; these food production systems require particular attention to prevent spread of such resistance from these sources.

If a full risk assessment for a specific food-bacterium combination, in respect of AMR, should be undertaken, methodologies currently available for the risk assessment of foods would require modification for uniform adaptation at both MS and EU level. The risk assessment would need to cover the combinations (including foods originating from food animals, fish, fresh produce (eg, lettuce etc) and water, as vehicles for the transmission of AMR bacteria and related genes).

Overall, control of all the routes by which AMR bacteria and their related genes can arise in the human patient, of which food is but one such route, requires a response from all stakeholders to acknowledge their responsibilities for preventing both the development and spread of AMR, each in their own area of activity including medicine, veterinary medicine, primary food animal production, food processing and food preparation, as well as in the regulation of food safety.

The BIOHAZ opinion represents a basis for further risk assessment studies on AMR bacteria in the food chain, as well as a firm input for risk managers to develop further approaches in dealing with AMR.