Escherichia coli carrying IncI2 plasmid-mediated mcr-1 genes in crested ibis (Nipponia nippon)

Antimicrobial resistance is a quintessential One Health issue, among the most serious 21st century global threats in human and veterinary medicine. Wild animals are usually not directly exposed to clinically relevant antibiotics; however, antibacterial resistance in wild animals has been increasingly reported worldwide in parallel to the situation in human and veterinary medicine. In this work, we collected 100 fecal samples from the crested ibis protected areas. A total of eight Escherichia coli (E. coli) isolates positive for mcr-1 were obtained, and all of them were analyzed using WGS (whole genome sequencing). The WGS analysis showed that the isolates were assigned to four different sequence types (ST) overall. The antibiotic susceptibility profile showed that of eight E. coli isolates, six strains exhibited resistance to tetracycline and all mcr-1-positive E. coli (MCREC) strains showed resistance to colistin. Our findings importantly document the epidemic spread of MCREC in crested ibis in China.