Emergence of a Hypermucoviscous Strain Coproducing Carbapenemase-2 and New Delhi Metallo-β-Lactamase-5 Carbapenemases in Shanghai, China.

Recently, the emergence of carbapenem-resistant hypermucoviscous has aroused increasing attention in China. We investigated the characteristics of a carbapenemase-2 (KPC-2) and New Delhi metallo-β-lactamase-5 (NDM-5) coproducing hypermucoviscous strain, named RJ-8061, which was isolated from the urine of an 86-year-old female patient with pneumonia. The RJ-8061 strain was investigated by string test, antimicrobial susceptibility testing, polymerase chain reaction for carbapenemase genes detection, capsular genotyping, multilocus sequence typing, whole-genome sequencing, and phylogenetics. A serum killing assay and a infection model were used to evaluate the virulence of RJ-8061 and . RJ-8061 belonged to the sequence type 11 K64 serotype and showed high-level resistance to almost all frequently used antibiotics, only remaining susceptible to amikacin, colistin, and tigecycline. The complete genome size of RJ-8061 was 6,106,028 bp, including a 5,394,921 bp chromosome and seven circular plasmids. Plasmid pRJ-8061-hybrid is a 294,249 bp hybrid plasmid that co-harbored resistance genes [, , ] and virulence genes (, ), whereas is a truncated version. In addition, and were located on plasmids 171,321 bp pRJ-8061-KPC-2 (IncFII/IncR) and 46,161 bp pRJ-8061-NDM-5 (IncX3), respectively. K-mer-based phylogenetic analysis grouped RJ-8061 into a carbapenem-resistant cluster. The infection model revealed that RJ-8061 showed relatively low virulence, with a 50% lethal dose of 10 cfu. To the best of our knowledge, this is the first report of a hypermucoviscous coproducing KPC-2 and NDM-5 carbapenemases.