Wild Nutria (Myocastor coypus) Is a Potential Reservoir of Carbapenem-Resistant and Zoonotic Aeromonas spp. in Korea

Abstract

The emergence and spread of antibiotic-resistant Aeromonas spp. is a serious public and animal health concern. Wild animals serve as reservoirs, vectors, and sentinels of these bacteria and can facilitate their transmission to humans and livestock. The nutria (Myocastor coypus), a semi-aquatic rodent, currently is globally considered an invasive alien species that has harmful impacts on natural ecosystems and carries various zoonotic aquatic pathogens. This study aimed to determine the prevalence of antibiotic-resistant zoonotic Aeromonas spp. in wild invasive nutrias captured in Korea during governmental eradication program. Three potential zoonotic Aeromonas spp. (A. hydrophila, A. caviae, and A. dhakensis) were identified among isolates from nutria. Some strains showed unexpected resistance to fluoroquinolones, third-generation cephalosporins, and carbapenems. In carbapenem-resistant isolates, the cphA gene, which is related to intrinsic resistance of Aeromonas to carbapenems, was identified, and phylogenetic analysis based on this gene revealed the presence of two major groups represented by A. hydrophila (including A. dhakensis) and other Aeromonas spp. These results indicate that wild nutrias in Korea are a potential reservoir of zoonotic and antibiotic-resistant Aeromonas spp. that can cause infection and treatment failure in humans. Thus, measures to prevent contact of wild nutrias with livestock and humans are needed.

Keywords: Aeromonas spp.; antibiotic resistance; carbapenem; cphA; nutria (Myocastor coypus).

Figure 1

Neighbor-joining phylogenetic tree based on gyrB nucleotide sequences showing the relationships of all Aeromonas isolates reported in this study to some representative type strains of Aeromonas spp. and the outgroup Vibrio cholerae CECT 514^T. The scale bar represents 0.05 nucleotide substitutions per site.

Figure 2

Maximum-likelihood phylogenetic tree based on cphA amino acid sequences showing the relationships of the deduced amino acid sequences of 11 cphA genes reported in this study to eight representative cphA variants in Aeromonadaceae. The scale bar represents 0.01 amino acid substitutions per site.