Molecular Characterization of the First Emerged NDM-1-Producing Isolates in South Korea.

Carbapenemase-producing (CPPA) is a threat to public health. This study aimed to describe the first emergence and molecular characterization of NDM-1-producing in South Korea. A total of 183 carbapenem-resistant (CRPA) isolates were recovered from patients at a university hospital in Seoul, South Korea. The antimicrobial resistance genes and their genetic environments were determined through molecular sequencing. Antimicrobial susceptibility testing was performed using the VITEK 2 system and broth microdilution method. Genetic relatedness was assessed using multilocus sequence typing and pulsed-field gel electrophoresis. Whole genome sequencing (WGS) was carried out to analyze the entire genome of a CPPA isolated from the index patient; the first identified infected patient. All 16 CPPA isolates from the 183 CRPA carried the gene and exhibited a high level of resistance to β-lactams, aminoglycosides, and ciprofloxacin. Fifteen of the 16 isolates were recovered from urine samples. They were attributed to ST773 and showed high clonal similarity (>86%). Post-WGS analysis revealed that the gene and the 16S rRNA methyltransferase gene were located in the integrative and conjugative element (ICE) on the chromosome. This ICE region was very similar to the ICE region carrying the gene and the 16S rRNA methyltransferase gene in a previously described strain. This study described the first emergence and clonal spread of the NDM-1-producing ST773 isolates possessing , at a university hospital in South Korea, suggesting that continuous surveillance is necessary to prevent infection and transmission of these CRPAs, which can endanger public health.