Unravelling the Diversity and Abundance of the Red Fox (Vulpes vulpes) Faecal Resistome and the Phenotypic Antibiotic Susceptibility of Indicator Bacteria

SIMPLE SUMMARY: Antimicrobial resistance was considered one of the major concerns of the twenty-first century by the World Health Organization in 2014. A holistic approach known as “One Health” recognizes the connections and interdependence between the health of people, domestic and wild animals, plants, and the ecosystem. The red fox is the most widespread wild canid in Europe that adapts easily and is distributed in natural environments and urban and peri-urban areas due to its increasing abundance. Foxes are reservoirs and disseminators of antibiotic resistance and zoonotic agents. They interact with watercourses, soils and livestock, and although they have no gastronomic interest, they are a game species, highlighting the potential risk of contamination between them and the hunters. Our main goal was to characterize antibiotic resistance in red foxes. Several clinically relevant antibiotic resistance genes were identified, as well as multidrug-resistant bacteria. ABSTRACT: The WHO considers that antimicrobial resistance (AMR) is among the ten greatest global public health risks of the 21st century. The expansion of human populations and anthropogenically related activities, accompanied by the fragmentation of natural habitats, has resulted in increased human–wildlife interaction. Natural ecosystems are therefore subjected to anthropogenic inputs, which affect the resistome of wild animals. Thus, urgent multisectoral action is needed to achieve the Sustainable Development Goals following the One Health approach. The present work falls within the scope of this approach and aims to characterize the AMR of the faecal microbiome of the red fox (Vulpes vulpes), an opportunistic and generalist synanthropic species whose abundance has been increasing in urban and peri-urban areas. A high number of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) were screened and quantified using a high-throughput qPCR approach, and the antimicrobial susceptibility of cultivable E. coli and Enterococcus spp. were assessed interpreted with both ECOFFs and clinical breakpoints. The most abundant ARGs detected confer resistance to trimethoprim and tetracyclines, although the first were absent in one of the locations studied. Several ARGs considered to be threats to human health were identified in high relative abundances (bla(TEM), ermB, aadA, tetM, tetW, tetL, drfA1 and drfA17), especially in the geographical area with greater anthropogenic influence. Although at a low percentage, resistant and multidrug-resistant (MDR) E. coli and Enterococcus spp. were isolated, including one MDR E. coli showing resistance to 12 antimicrobials from 6 different classes.