Genomic characterization of carbapenem-resistant complex in China: a multi-center study.

Carbapenem-resistant (CR) complex can be associated with high mortality, emerging as a new threat to the public health. complex is phylogenetically close to , one of most common species associated with multidrug resistance in Enterobacterale. The latest research showed that is a complex of six species. Currently, the epidemiological and genomic characteristics of CR complex in China are still unclear. Here, we conducted a multi-center study on 25 CR complex collected from five representative regions in China. These isolates were, respectively, recovered from respiratory tract (12 cases, 48.0%), abdominal cavity (5 cases, 20.0%), blood (4 cases, 16.0%), urine tract (3 cases, 12.0%) and skin or soft tissue (1 cases, 4.0%). Among them, 32.0% (8/25) of patients infected with complex had a poor prognosis. In this study, three complex species were detected, namely , and , among which was the most common. Three carbapenemase genes were identified, including (10, 38.5%), (9, 34.6%) and (6 and 1 ; 7, 26.9%). Subsequent multilocus sequence typing identified various sequence types (STs), among which ST43, ST92 and ST145 were relatively common. Different from the clonal dissemination of high-risk carbapenem-resistant strains, our research revealed a polyclonal dissemination characteristic of CR complex in China. S1-nuclease PFGE and Southern blot experiment showed that carbapenemase genes were encoded in plasmids of different sizes. Two -harboring plasmids were subsequently sequenced, and were characterized to be IncX3 and IncC incompatibility groups, respectively. This is the first multi-center study of CR complex in China, which improved our understanding of the prevalence and antimicrobial resistance characteristics of CR complex in China.