Scientific Opinion on the public health risks of bacterial strains producing extended-spectrum β-lactamases and/or AmpC β-lactamases in food and food-producing animals

The potential contribution of food-producing animals or foods to public health risks by ESBL and/or AmpC-producing bacteria is related to specific plasmid-mediated ESBL and/or AmpC genes encoded by a number of organisms. The predominant ESBL families encountered are CTX-M, TEM, and SHV; the predominant AmpC-family is CMY. The most common genes associated with this resistance in animals are bla_CTX-M-1 (the most commonly identified ESBL), and bla_CTX-M-14, followed by bla_TEM-52 and bla_SHV-12. Among the genes encoding AmpC-type β-lactamases, bla_CMY-2 is the most common.The bacterial species most commonly identified with these genes are Escherichia coli and non-typhoidal Salmonella. ESBL/AmpC transmission is mainly driven by integrons, insertion sequences, transposons and plasmids, some of which are homologous in isolates from both food-production animals and humans. Cefotaxime is used as the drug of choice for optimum detection of bla_ESBL and/or bla_AmpC genes. The preferred method for isolation of ESBL- and/or AmpC-producers is screening on selective agar preceded by selective enrichment in a broth.The establishment of risk factors for occurrence of ESBL/AmpC-producing bacteria is particularly complicated by the data unavailability or lack of its accuracy. The use of antimicrobials is a risk factor for the selection and spread of resistant clones, resistance genes and plasmids. Since most ESBL- and AmpC-producing strains carry additional resistances to other commonly-used veterinary drugs, generic antimicrobial use is a risk factor for ESBL/AmpC and it is not restricted specifically to the use of cephalosporins. An additional risk factor is extensive trade of animals in EU MS. There are no data on the comparative efficiency of individual control options in reducing public health risks caused by ESBL and/or AmpC-producing bacteria related to food-producing animals. Prioritisation is complex, but it is considered that a highly effective control option would be to stop all uses of cephalosporins/systemically active 3^rd/4^th generation cephalosporins, or to restrict their use (use only allowed under specific circumstances). As co-resistance is an important issue, it is also of high priority to decrease the total antimicrobial use in animal production in the EU.