Coexistence of plasmid-mediated <i>tmexCD2-toprJ2</i> , <i>bla</i> _IMP-4 , and <i>bla</i> _NDM-1 in <i>Klebsiella quasipneumoniae</i>

<i>Klebsiella quasipneumoniae</i> is a potential pathogen that has not been studied comprehensively. The emergence of multidrug-resistant (MDR) <i>K. quasipneumoniae</i>, specifically strains resistant to tigecycline and carbapenem, presents a significant challenge to clinical treatment. This investigation aimed to characterize MDR <i>K. quasipneumoniae</i> strain FK8966, co-carrying <i>tmexCD2-toprJ2</i>, <i>bla</i>_IMP-4, and <i>bla</i>_NDM-1 by plasmids. It was observed that FK8966's MDR was primarily because of the IncHI1B-like plasmid co-carrying <i>tmexCD2-toprJ2</i> and <i>bla</i>_IMP-4, and an IncFIB(K)/IncFII(K) plasmid harboring <i>bla</i>_NDM-1. Furthermore, the phylogenetic analysis revealed that IncHI1B-like plasmids carrying <i>tmexCD2-toprJ2</i> were disseminated among different bacteria, specifically in China. Additionally, according to the comparative genomic analysis, the MDR regions indicated that the <i>tmexCD2-toprJ2</i> gene cluster was inserted into the <i>umuC</i> gene, while <i>bla</i>_IMP-4 was present in transposon Tn<i>As3</i> linked to the class 1 integron (<i>IntI1</i>). It was also observed that an ΔTn<i>3000</i> insertion with <i>bla</i>_NDM-1 made a novel <i>bla</i>_NDM-1 harboring IncFIB(K)/IncFII(K) plasmid. The antimicrobial resistance prevalence and phylogenetic analyses of <i>K. quasipneumoniae</i> strains indicated that FK8966 is a distinct MDR branch of <i>K. quasipneumoniae</i>. Furthermore, CRISPR-Cas system analysis showed that many <i>K. quasipneumoniae</i> CRISPR-Cas systems lacked spacers matching the two aforementioned novel resistance plasmids, suggesting that these resistance plasmids have the potential to disseminate within <i>K. quasipneumoniae</i>. Therefore, the spread of MDR <i>K. quasipneumoniae</i> and plasmids warrants further attention.IMPORTANCEThe emergence of multidrug-resistant <i>K. quasipneumoniae</i> poses a great threat to clinical care, and the situation is exacerbated by the dissemination of tigecycline- and carbapenem-resistant genes. Therefore, monitoring these pathogens and their resistance plasmids is urgent and crucial. This study identified tigecycline- and carbapenem-resistant <i>K. quasipneumoniae</i> strain, FK8966. Furthermore, it is the first study to report the coexistence of <i>tmexCD2-toprJ2</i>, <i>bla</i>_IMP-4, and <i>bla</i>_NDM-1 in <i>K. quasipneumoniae</i>. Moreover, the CRISPR-Cas system of many <i>K. quasipneumoniae</i> lacks spacers that match the plasmids carried by FK8966, which are crucial for mediating resistance against tigecycline and carbapenems, indicating their potential to disseminate within <i>K. quasipneumoniae</i>.