Characterization difference of typical KL1, KL2 and ST11-KL64 hypervirulent and carbapenem-resistant Klebsiella pneumoniae.

Almost all the formation of hypervirulent and carbapenem-resistant Klebsiella pneumoniae follow two major patterns: KL1/KL2 hvKP strains acquire carbapenem-resistance plasmids (CR-hvKP), and carbapenem-resistant Klebsiella pneumoniae (CRKP) strains obtain virulence plasmids (hv-CRKP). These two patterns may pose different phenotypes. In this study, three typical resistance and hypervirulent K. pneumoniae (KL1, KL2, and ST11-KL64), isolating from poor prognosis patients, were selected. Compared with ST11-KL64 hv-CRKP, KL1/KL2 hypervirulent lineages harbor significantly fewer resistance determinants and exhibited lower-level resistance to antibiotics. Notably, though the blaKPC gene could be detected in all these isolates, KL1/KL2 hvKP strain did not exhibit corresponding high-level carbapenem resistance. Unlike the resistance features, we did not observe significant virulence differences between the three strains. The ST11-KL64 hv-CRKP (1403) in this study, showed similar mucoviscosity, siderophores production, and biofilm production compared with KL1 and KL2 hvKP. Moreover, the hypervirulent of ST11-KL64 hvKP also verified with the human lung epithelial cells infection and G. mellonella infection models. Moreover, we found the pLVPK-like virulence plasmid and IncF blaKPC-2 plasmid was crucial for the formation of hypervirulent and carbapenem-resistant K. pneumoniae. The conservation of origin of transfer site (oriT) in these virulence and blaKPC-2 plasmids, indicated the virulence plasmids could transfer to CRKP with the help of blaKPC-2 plasmids. The co-existence of virulence plasmid and blaKPC-2 plasmid facilitate the formation of ST11-KL64 hv-CPKP, which then become nosocomial epidemic under the antibiotic stress. The ST11-KL64 hv-CPKP may poses a substantial threat to healthcare networks, urgent measures were needed to prevent further dissemination in nosocomial settings.

Zhou Y ，Wu C ，Wang B ，Xu Y ，Zhao H ，Guo Y ，Wu X ，Yu J ，Rao L ，Wang X ，Yu F ... -  《-》

Virulence plasmid with IroBCDN deletion promoted cross-regional transmission of ST11-KL64 carbapenem-resistant hypervirulent Klebsiella pneumoniae in central China.

Carbapenem-resistant and hypervirulent Klebsiella pneumoniae (CR-hvKP) caused infections of high mortality and brought a serious impact on public health. This study aims to evaluate the epidemiology, resistance and virulence characteristics of CR-hvKP and to identify potential drivers of cross-regional transmission in different regions of China, in order to provide a basis for developing targeted prevention measures. Clinical K. pneumoniae strains were collected from Jiujiang and Nanchang in Jiangxi province between November 2021 to June 2022. Clinical data of patients (age, sex, source of infection, and diagnosis) were also gathered. We characterized these strains for their genetic relatedness using PFGE, antimicrobial and virulence plasmid structures using whole-genome sequencing, and toxicity using Galleria mellonella infection model. Among 609 strains, 45 (7.4%) CR-hvKP were identified, while the strains. isolated from Nanchang and Jiujiang accounted for 10.05% (36/358) and 3.59% (9/251). We observed that ST11-KL64 CR-hvKP had an overwhelming epidemic dominance in these two regions. Significant genetic diversity was identified among all ST11-KL64 CR-hvKP cross-regional transmission between Nanchang and Jiujiang and this diversity served as the primary driver of the dissemination of clonal groups. Virulence genes profile revealed that ST11-KL64 CR-hvKP might harbour incomplete pLVPK-like plasmids and primarily evolved from CRKP by acquiring the hypervirulence plasmid. We found the predominance of truncated-IncFIB/IncHI1B type virulence plasmids with a 25 kb fragment deletion that encoded iroBCDN clusters. ST11-KL64 is the most cross-regional prevalent type CR-hvKPs in Jiangxi province, which mainly evolved from CRKPs by acquiring a truncated-IncHI1B/IncFIB virulence plasmid with the deletion of iroBCDN. Stricter surveillance and control measures are urgently needed to prevent the epidemic transmission of ST11-KL64 CR-hvKP.

Hong HX ，Huo BH ，Xiang TX ，Wei DD ，Huang QS ，Liu P ，Zhang W ，Xu Y ，Liu Y ... -  《BMC MICROBIOLOGY》

Emergence of IS26-mediated pLVPK-like virulence and NDM-1 conjugative fusion plasmid in hypervirulent carbapenem-resistant Klebsiella pneumoniae.

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) has been widely reported and poses a global threat. However, the comprehensive genetic structure of ST11-KL64 hv-CRKP and the possible evolutionary mechanisms from a genetic structure perspective of this high-risk clone remain unclear. Here, a blaKPC-2-blaNDM-1-positive ST11-KL64 hv-CRKP isolate was obtained from a human bloodstream infection (BSI). Whole-genome sequencing and bioinformatics analyses revealed that it contained a fusion plasmid, pKPTCM2-1. pKPTCM2-1 is a conjugative plasmid composed of an oriT-positive pLVPK-like virulence plasmid and a type IV secretion system-produced blaNDM-1-bearing IncX3 plasmid mediated by IS26-based co-integration. This progress generated 8-bp target site duplications (TGAAAACC) on both sides. The fusion plasmid possessed self-transferability and could be transferred to blaKPC-2-harboring ST11-KL64 CRKP to form the ST11-KL64 hv-CRKP clone. The pLVPK-like-positive ST11-KL64 strain exhibited virulence levels similar to those of the typical hypervirulent K. pneumoniae NTUH-2044. The mutation, Tet(A) (A276S), which was believed to lead to tigecycline resistance was observed. Overall, this high-risk clone has emerged as a tremendous threat in fatal BSIs and thus, targeted surveillance is an urgent need to contain the hv-CRKP clones.

Tian C ，Shi Y ，Ren L ，Huang D ，Wang S ，Zhao Y ，Fu L ，Bai Y ，Xia D ，Fan X ... -  《-》

Prevalence of hypervirulent and carbapenem-resistant Klebsiella pneumoniae under divergent evolutionary patterns.

Tian D ，Liu X ，Chen W ，Zhou Y ，Hu D ，Wang W ，Wu J ，Mu Q ，Jiang X ... -  《Emerging Microbes & Infections》

Nosocomial transmission and rearrangement of large resistance-virulence hybrid plasmids between two bacteremic ST11 carbapenem-resistant hypervirulent Klebsiella pneumoniae strains with low fitness cost.

To characterize nosocomial transmission and rearrangement of the resistance-virulence plasmid between two ST11-K64 carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) strains (JX-CR-hvKP-10 and JX-CR-hvKP-9) with low fitness. Phenotypic tests were used to assess the virulence of JX-CR-hvKP-10 and JX-CR-hvKP-9. Whole-genome sequencing was used to analyze JX-CR-hvKP-10 and JX-CR-hvKP-9 chromosomes and plasmids. Fitness and conjugation experiments were also conducted using these two CR-hvKP isolates. Phenotypic tests indicated that both JX-CR-hvKP-10 and JX-CR-hvKP-9 were multidrug-resistant and hypervirulent K. pneumoniae. Whole-genome sequencing and clinical information demonstrated that the super large resistance-virulence fusion plasmid pJX10-1 formed precisely by the fusion of pJX9-1 and pJX9-2 via the nosocomial transmission. Interestingly pJX9-1 itself was also a classic resistance-virulence fusion plasmid by way of the blaKPC-carrying resistance plasmid and pLVPK-like virulence plasmid. Compared with classic K. pneumoniae ATCC700603, fitness analysis revealed no significant difference in growth was observed between JX-CR-hvKP-10 and JX-CR-hvKP-9. Nosocomial transmission and rearrangement of a blaKPC-harboring plasmid and a pLVPK-like virulence plasmid with a low fitness cost in ST11 K. pneumoniae enhances drug resistance and virulence simultaneously. Thus, active surveillance of this hybrid plasmid is needed to prevent these efficient resistance-virulence plasmids from disseminating in hospital settings.

Liao W ，Huang QS ，Wei D ，Xiong Z ，Du FL ，Xiang TX ，Zhang S ，Wan LG ，Zhang W ，Liu Y ... -  《-》