Analysis of fecal samples from Amami rabbits (Pentalagus furnessi) indicates low levels of antimicrobial resistance in Escherichia coli

Abstract

In recent years, antimicrobial-resistant bacteria have been isolated from different wildlife species that have not been exposed to antibiotics. Antimicrobial resistance profile analysis of wildlife-derived Escherichia coli is one of the ways to obtain information about changes in wildlife habitats. The Amami rabbit (Pentalagus furnessi) is one of the Japanese endemic wildlife species that requires conservation due to its declining population. However, detailed information on its ecology, including habitat, is unclear. We conducted antimicrobial susceptibility testing (broth microdilution assay) of 12 antimicrobials on 135 E. coli strains isolated from the feces of free-living Amami rabbits, collected between 2017 and 2020. No antimicrobial-resistant E. coli were isolated from any sample, indicating that antimicrobial-resistant E. coli were not widely distributed in the Amami rabbit population. In addition, these results suggested that the habitat of Amami rabbits may not be contaminated with antimicrobials derived from humans, Japanese livestock, and wildlife that come in contact with the rabbits. This is the first study to examine the antimicrobial resistance of bacterial isolates from the Amami rabbits for a multi-year period. In order to observe changes in wildlife habitats on the Amami-Oshima Island, inhabited by many rare species including Amami rabbits, continued surveillance of antimicrobial-resistant E. coli in wildlife is necessary.