Abstract
Animal and food sources are seen as a potential transmission pathway of antimicrobial resistance (AMR) to humans. The aim of this study is to describe Campylobacter, Salmonella, and commensal Escherichia coli multi-drug resistance (MDR) in the food chain between 2014 and 2019 in Portugal. AMR surveillance data from food-producing animals and food were assessed. MDR relative frequencies were estimated by bacterial genus and year. AMR profiles were created using observations of resistance to antimicrobial classes from each isolate. Antimicrobial susceptibility testing results were clustered using k-modes. Clusters were described by population, AMR classification, β-lactamases, sample stage, sample type, season, and year. Overall, MDR was more prevalent for E. coli, ranging from 74–90% in animal and 94–100% in food samples. MDR was found to be more widespread in resistance profiles that were common among E. coli and Salmonella isolates and in those exclusively observed for E. coli, frequently including (fluoro)quinolones and cephalosporins resistance. β-lactam resistance was observed around 75% to 3rd/4th-generation cephalosporins in E. coli. Clusters suggest an escalating MDR behaviour from farm to post-farm stages in all bacteria and that Salmonella (fluoro)quinolones resistance may be associated with broilers. These findings support policy and decision making to tackle MDR in farm and post-farm stages.
Highlights
Anthropogenic, commensal, and environmental bacteria collectively contribute to the antimicrobial resistance (AMR), increasing human vulnerability through resistant strains that colonize the intestinal tract and transfer resistance genes [1,2,3]
AMR evolution can be influenced jointly by factors, such as bacteria environmental persistence, host immune status, microflora composition, and antimicrobial interventions [7]. This evolution can result in multi-drug resistance (MDR), i.e., resistance to three or more antimicrobial classes, affecting the usefulness of multiple last-resort antimicrobials, such as 3rd-generation cephalosporins and carbapenems, two of the leading antimicrobial classes used in the treatment of MDR infections [8,9]
Multiresistance was more prevalent for E. coli isolates, ranging from 74% to 90% in animal populations (Figure 1A,B) and 94% to 100% in food products (Figure 1C,D)
Summary
Anthropogenic, commensal, and environmental bacteria collectively contribute to the antimicrobial resistance (AMR), increasing human vulnerability through resistant strains that colonize the intestinal tract and transfer resistance genes [1,2,3]. AMR evolution can be influenced jointly by factors, such as bacteria environmental persistence, host immune status, microflora composition, and antimicrobial interventions [7]. This evolution can result in multi-drug resistance (MDR), i.e., resistance to three or more antimicrobial classes, affecting the usefulness of multiple last-resort antimicrobials, such as 3rd-generation cephalosporins and carbapenems, two of the leading antimicrobial classes used in the treatment of MDR infections [8,9]. While AMR cannot be realistically eradicated, antimicrobials will continue to lose their efficacy, and, in the near future, more people may die from infections as treatment options disappear [11]
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