AUTHOR=Zhao Junhui , Zheng Beiwen , Xu Hao , Li Junfeng , Sun Tengfei , Jiang Xiawei , Liu Wenhong 

TITLE=Emergence of a NDM-1-producing ST25 Klebsiella pneumoniae strain causing neonatal sepsis in China

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.980191

DOI=10.3389/fmicb.2022.980191

ISSN=1664-302X

ABSTRACT=<p>Carbapenem-resistant <italic>Klebsiella pneumoniae</italic> (CRKP) seriously threaten the efficacy of modern medicine with a high associated mortality rate and unprecedented transmission rate. In this study, we isolated a clinical <italic>K. pneumoniae</italic> strain DY1928 harboring <italic>bla</italic><sub>NDM-1</sub> from a neonate with blood infection. Antimicrobial susceptibility testing indicated that DY1928 was resistant to various antimicrobial agents, including meropenem, imipenem, ceftriaxone, cefotaxime, ceftazidime, cefepime, piperacillin-tazobactam, and amoxicillin-clavulanate. S1 nuclease-pulsed field gel electrophoresis (S1-PFGE), southern blot and conjugation experiment revealed that the <italic>bla</italic><sub>NDM-1</sub> gene was located on a conjugative plasmid of IncA/C2 type with a 147.9 kb length. Whole-genome sequencing showed that there was a conservative structure sequence (<italic>bla</italic><sub>NDM-1</sub>-<italic>ble</italic>-<italic>trpF</italic>-<italic>dsbD</italic>) located downstream of the <italic>bla</italic><sub>NDM-1</sub> gene. Multilocus sequence typing (MLST) classified DY1928 as ST25, which was a hypervirulent <italic>K. pneumoniae</italic> type. Phylogenetic analysis of genomic data from all ST25 <italic>K. pneumoniae</italic> strains available in the NCBI database suggested that all <italic>bla</italic><sub>NDM-1</sub> positive strains were isolated in China and had clinical origins. A mouse bloodstream infection model was constructed to test the virulence of DY1928, and 11 <italic>K. pneumoniae</italic> strains homologous to DY1928 were isolated from the feces of infected mice. Moreover, we found that DY1928 had a tendency to flow from the blood into the intestine in mice and caused multiple organ damage. To our knowledge, this is the first study to report an infection caused by <italic>bla</italic><sub>NDM-1</sub>-positive ST25 <italic>K. pneumoniae</italic> in the neonatal unit. Our findings indicated that stricter surveillance and more effective actions were needed to reduce the risk of disseminating such <italic>K. pneumoniae</italic> strains in clinical settings, especially in neonatal wards.</p>