Antimicrobial resistant bacteria in wild mammals and birds: a coincidence or cause for concern?

Background: The emergence and dissemination of antimicrobial resistance (AMR) is a growing concern to public and animal health. The contribution attributable to wildlife remains unclear. In this study two unrelated wildlife species herring gulls (Larus argentatus) and a hybrid deer (Cervus elaphus x Cervus nippon) were investigated for the presence of Escherichia coli expressing an AMR phenotype. Findings: Bacterial isolates resistant to beta-lactam compounds were identified in both animal species and the production of functional beta-lactamase was confirmed using nitrocefin. The prevalence of resistant isolates was higher in herring gulls (87%) compared to deer (31%). Resistance to this class of antibiotic was found only in non-pathogenic E. coli in herring gulls and in both pathogenic and non-pathogenic E. coli strains in deer. Conclusions: The presence of AMR in wildlife has implications for public health, food safety and potable water source protection among others.