Emergence of Colistin Resistance Gene mcr-8 and Its Variant in Raoultella ornithinolytica

Recently, a novel mobile colistin resistance gene, , was identified in . Here, we report the identification of and its variant, , in isolates which also belong to Enterobacteriaceae family. The gene was located on transferrable plasmids with difference sizes. Notably, the transferability of -carrying plasmids was enhanced once they entered into hosts and multiple β-lactamase genes could co-transfer with . These findings expand our knowledge of -carrying bacterial species.