AUTHOR=Wan Weimin , Yang Xiaochun , Yu Hua , Wang Min , Jia Wei , Huang Bin , Qu Fen , Shan Bin , Tang Yi-Wei , Chen Liang , Du Hong 

TITLE=Genomic characterization of carbapenem-resistant Klebsiella oxytoca complex in China: a multi-center study

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1153781

DOI=10.3389/fmicb.2023.1153781

ISSN=1664-302X

ABSTRACT=<p>Carbapenem-resistant (CR) <italic>Klebsiella oxytoca</italic> complex can be associated with high mortality, emerging as a new threat to the public health. <italic>K. oxytoca</italic> complex is phylogenetically close to <italic>K. pneumoniae</italic>, one of most common species associated with multidrug resistance in Enterobacterale. The latest research showed that <italic>K. oxytoca</italic> is a complex of six species. Currently, the epidemiological and genomic characteristics of CR <italic>K. oxytoca</italic> complex in China are still unclear. Here, we conducted a multi-center study on 25 CR <italic>K. oxytoca</italic> 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 <italic>K. oxytoca</italic> complex had a poor prognosis. In this study, three <italic>K. oxytoca</italic> complex species were detected, namely <italic>K. michiganensis</italic>, <italic>K. oxytoca</italic> and <italic>K. pasteurii</italic>, among which <italic>K. michiganensis</italic> was the most common. Three carbapenemase genes were identified, including <italic>bla</italic><sub>NDM-1</sub> (10, 38.5%), <italic>bla</italic><sub>KPC-2</sub> (9, 34.6%) and <italic>bla</italic><sub>IMP</sub> (6 <italic>bla</italic><sub>IMP-4</sub> and 1 <italic>bla</italic><sub>IMP-8</sub>; 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 <italic>K. pneumoniae</italic> strains, our research revealed a polyclonal dissemination characteristic of CR <italic>K. oxytoca</italic> complex in China. S1-nuclease PFGE and Southern blot experiment showed that carbapenemase genes were encoded in plasmids of different sizes. Two <italic>bla</italic><sub>NDM</sub>-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 <italic>K. oxytoca</italic> complex in China, which improved our understanding of the prevalence and antimicrobial resistance characteristics of CR <italic>K. oxytoca</italic> complex in China.</p>