Characterization of an NDM-5-producing hypervirulent Klebsiella pneumoniae sequence type 65 clone from a lung transplant recipient

Occurrence of high-risk clones of Klebsiella pneumoniae ST11, ST340, and ST855 carrying the blaKPC-2, blaNDM-1, blaNDM-5, and blaNDM-7 genes from colonized and infected patients in Brazil

AIMS

Determine which sequence type (ST) clones were carrying the blaKPC, blaNDM, blaVIM, blaIMP, and blaGES genes and their variants in clinical isolates of multidrug-resistant Klebsiella pneumoniae.

METHODS AND RESULTS

Ten K. pneumoniae isolates were obtained from the colonized and infected patients in a public hospital in the city of Recife-PE, in northeastern Brazil, and were further analyzed. The detection of carbapenem resistance genes and the seven housekeeping genes [for multilocus sequence typing (MLST) detection] were done with PCR and sequencing. The blaKPC and blaNDM genes were detected concomitantly in all isolates, with variants being detected blaNDM-1, blaNDM-5, blaNDM-7, and blaKPC-2. The blaKPC-2 and blaNDM-1 combination being the most frequent. Molecular typing by MLST detected three types of high-risk ST clones, associated with the clonal complex 258, ST11/CC258 in eight isolates, and ST855/CC258 and ST340/CC258 in the other two isolates.

CONCLUSIONS

These findings are worrying, as they have a negative impact on the scenario of antimicrobial resistance, and show the high genetic variability of K. pneumoniae and its ability to mutate resistance genes and risk of dissemination via different ST clones.

Global spread and evolutionary convergence of multidrug-resistant and hypervirulent Klebsiella pneumoniae high-risk clones

For people living in developed countries life span is growing at a faster pace than ever. One of the main reasons for such success is attributable to the introduction and extensive use in the clinical practice of antibiotics over the course of the last seven decades. In hospital settings, Klebsiella pneumoniae represents a well-known and commonly described opportunistic pathogen, typically characterized by resistance to several antibiotic classes. On the other hand, the broad wedge of population living in Low and/or Middle Income Countries is increasing rapidly, allowing the spread of several commensal bacteria which are transmitted via human contact. Community transmission has been the original milieu of K. pneumoniae isolates characterized by an outstanding virulence (hypervirulent). These two characteristics, also defined as "pathotypes", originally emerged as different pathways in the evolutionary history of K. pneumoniae. For a long time, the Sequence Type (ST), which is defined by the combination of alleles of the 7 housekeeping genes of the Multi-Locus Sequence Typing, has been a reliable marker of the pathotype: multidrug-resistant clones (e.g. ST258, ST147, ST101) in the Western world and hypervirulent clones (e.g. ST23, ST65, ST86) in the Eastern. Currently, the boundaries separating the two pathotypes are fading away due to several factors, and we are witnessing a worrisome convergence in certain high-risk clones. Here we review the evidence available on confluence of multidrug-resistance and hypervirulence in specific K. pneumoniae clones.

Prevalence and molecular characteristics of polymyxin-resistant Enterobacterales in a Chinese tertiary teaching hospital

Introduction

Polymyxin-resistant Enterobacterales poses a significant threat to public health globally, but its prevalence and genomic diversity within a sole hospital is less well known. In this study, the prevalence of polymyxin-resistant Enterobacterales in a Chinese teaching hospital was investigated with deciphering of their genetic determinants of drug resistance.

Methods

Polymyxin-resistant Enterobacterales isolates identified by matrix-assisted laser desorption were collected in Ruijin Hospital from May to December in 2021. Both the VITEK 2 Compact and broth dilution methods were used to determine polymyxin B (PMB) susceptibility. Polymyxin-resistant isolates were further characterized by molecular typing using PCR, multi-locus sequence typing, and sequencing of the whole genome.

Results

Of the 1,216 isolates collected, 32 (2.6%) across 12 wards were polymyxin-resistant (minimum inhibitory concentration (MIC) range, PMB 4-256 mg/ml, and colistin 4 ≥ 16 mg/ ml). A total of 28 (87.5%) of the polymyxin-resistant isolates had reduced susceptibility to imipenem and meropenem (MIC ≥ 16 mg/ml). Of the 32 patients, 15 patients received PMB treatment and 20 survived before discharge. The phylogenetic tree of these isolates showed they belonged to different clones and had multiple origins. The polymyxin-resistant Klebsiella pneumoniae isolates belonged to ST-11 (85.72%), ST-15 (10.71%), and ST-65 (3.57%), and the polymyxin-resistant Escherichia coli belonged to four different sequence types, namely, ST-69 (25.00%), ST-38 (25.00%), ST-648 (25.00%), and ST-1193 (25.00%). In addition, six mgrB specific mutations (snp_ALT c.323T>C and amino acid change p.Val8Ala) were identified in 15.6% (5/32) of the isolates. mcr-1, a plasmid-mediated polymyxin-resistant gene, was found in three isolates, and non-synonymous mutations including T157P, A246T, G53V, and I44L were also observed.

Discussion

In our study, a low prevalence of polymyxin-resistant Enterobacterales was observed, but these isolates were also identified as multidrug resistant. Therefore, efficient infection control measures should be implemented to prevent the further spread of resistance to last-line polymyxin therapy.

Emergence of Extensively Drug-Resistant and Hypervirulent KL2-ST65 Klebsiella pneumoniae Harboring blaKPC-3 in Beijing, China

Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKp) has been emerging worldwide. However, the clinical, microbiological, and genomic characteristics of newly emerged MDR sequence type 65 (ST65) hvKp are unclear. We conducted active longitudinal genomic surveillance of K. pneumoniae in the hospital starting in 2017. Clinical characteristics, including demographic data, infection type, and outcomes, were collected. Whole-genome sequencing was performed to clarify phylogenetic and plasmid features, and phenotype determined by growth curves, plasmid transferability and stability, hypermucoviscosity, biofilm formation, and serum survival were analyzed to microbiologically characterize ST65 in depth. Ten ST65 (1.4%, 10/720) isolates were detected from 720 K. pneumoniae isolates in total. Nine patients (90%, 9/10) were older than 60 years and had multiple underlying diseases. All ST65 K. pneumoniae isolates harbored iucA, rmpA, rmpA2, iroB, and peg344 and were identified as hvKp. Surprisingly, two MDR-hvKp isolates that grew slowly were observed. Isolate PEKP4222 harbored a pLVPK-like plasmid and a conjunctive MDR plasmid. Isolate P1 harbored blaKPC-3 in a new plasmid, pP1-54, resulting in an extensively drug-resistant (XDR) phenotype; this isolate, which might have evolved from a strain harboring blaKPC-2, resulted in fatal infection. The pP1-54 plasmid could not be transferred to Escherichia coli by conjugation but could be stably inherited vertically. Interestingly, P1 also carried the pLVPK-like plasmid and acquired various antimicrobial resistance genes, and blaCTX-M-3 was detected in the IncB/O/K/Z plasmid. The convergence of XDR and hypervirulence within classical ST65 hvKp is emerging, highlighting the need for enhanced genomic surveillance. IMPORTANCE XDR-hvKp poses a great challenge to public health. ST65, a classical hvKp subtype, mostly presented with hypermucoviscosity, which restricts antimicrobial resistance acquisition. However, few studies have demonstrated the clinical, microbiological, and genomic characteristics of ST65, especially MDR-ST65 hvKp. Here, we first reported that ST65 hvKp acquired blaKPC-3 and then conferred the XDR-hvKp phenotype. Genomic context analysis concluded that the blaKPC-3 gene might have evolved from blaKPC-2. Additionally, the pLVPK-like plasmid seemed to acquire more resistance genes, and blaCTX-M-3 located in the IncB/O/K/Z plasmid was observed. The XDR-hvKp phenotype could be stably inherited vertically, indicating that strains harboring blaKPC-3 and pLVPK-like plasmids could persistently exist in hospital settings. These data suggest that genomic adaptation is rapid and that enhanced surveillance is essential.

Resistance Phenotype and Molecular Epidemiology of Carbapenem-Resistant Klebsiella pneumoniae Isolated from Nanjing Children's Hospital in Jiangsu Province, China

Objective

The drug resistance phenotype and molecular epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) were identified among children in Jiangsu Province, China.

Methods

CRKP strains were collected from the Children’s Hospital of Nanjing Medical University from December 2020 to March 2022. CRKP strains were characterized for further study: antimicrobial susceptibility testing, carbapenem resistance genes and homology analysis.

Results

Among 86 strains of CRKP, 85 carried carbapenemase genes; the dominant gene was bla_KPC-2 (88.2%, 75/85), followed by bla_NDM-1 (4.7%, 4/85), bla_NDM-5 (4.7%, 4/85), bla_IMP-8 (2.3%, 2/85), and bla_OXA-181 (1.2%, 1/85). Among the 86 strains of CRKP, one isolate contained both the bla_NDM-5 and bla_OXA-181 genes, which is the first time that Klebsiella pneumoniae has been shown to jointly carry these genes in China. Another CRKP strain did not carry any carbapenemase gene. MLST analysis identified a total of 10 different sequence types, among which sequence type (ST) 11 was the most common. PFGE analysis identified 75 bla_KPC-2-producing CRKP ST11 strains, of which 68 were dominant clusters distributed among 11 different wards, mainly the neonatal medical centre (18 strains), neonatal surgery (17 strains) and cardiac care unit (CCU) (8 strains) wards.

Conclusion

Clonal dissemination of KPC-2-producing CRKP ST11 was observed in multiple departments. Additionally, non-ST11 strains showed high polymorphism based on molecular typing, indicating increasing diversity in CRKP strains. To our knowledge, this is the first report of NDM-5 and OXA-181-coproducing Klebsiella pneumoniae causing infection in children in China, which poses a significant health risk for paediatric patients. Active surveillance and effective control measures are urgently needed to prevent further transmission of these strains among children.

Epidemiological characteristics and molecular evolution mechanisms of carbapenem-resistant hypervirulent Klebsiella pneumoniae

Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP), a type of Klebsiella pneumoniae (KP) that exhibits hypervirulence and carbapenem resistance phenotypes, can cause severe infections, both hospital- and community-acquired infections. CR-hvKP has brought great challenges to global public health and is associated with significant morbidity and mortality. There are many mechanisms responsible for the evolution of the hypervirulence and carbapenem resistance phenotypes, such as the horizontal transfer of the plasmid carrying the carbapenem resistance gene to hypervirulent Klebsiella pneumoniae (hvKP) or carbapenemase-producing Klebsiella pneumoniae (CRKP) acquiring a hypervirulence plasmid carrying a virulence-encoding gene. Notably, KP can evolve into CR-hvKP by acquiring a hybrid plasmid carrying both the carbapenem resistance and hypervirulence genes. In this review, we summarize the evolutionary mechanisms of resistance and plasmid-borne virulence as well as the prevalence of CR-hvKP.

Successful treatment of acute respiratory distress syndrome caused by hypervirulent Klebsiella pneumoniae with extracorporeal membrane oxygenation and continuous renal replacement therapy: A case report and literature review

Hypervirulent Klebsiella pneumoniae (hvKP) causes invasive infections and leads to high morbidity and mortality rates. Here, we report the case of a Chinese man with diabetes mellitus who developed acute respiratory distress syndrome and septic shock due to hvKP belonging to the K1 strain. The patient was treated with venovenous extracorporeal membrane oxygenation and continuous renal replacement therapy, in combination with antibiotics and recovered well. Clinicians should be aware of fatal infections caused by hvKP and investigate the best treatment options for patients at various stages of infection.

Convergence of MCR-8.2 and Chromosome-Mediated Resistance to Colistin and Tigecycline in an NDM-5-Producing ST656 Klebsiella pneumoniae Isolate From a Lung Transplant Patient in China

We characterized the first NDM-5 and MCR-8.2 co-harboring ST656 Klebsiella pneumoniae clinical isolate, combining with chromosomal gene-mediated resistance to colistin and tigecycline. The K. pneumoniae KP32558 was isolated from the bronchoalveolar lavage fluid from a lung transplant patient. Complete genome sequences were obtained through Illumina HiSeq sequencing and nanopore sequencing. The acquired resistance genes and mutations in chromosome-encoded genes associated with colistin and tigecycline resistance were analyzed. Comparative genomic analysis was conducted between mcr-8.2-carrying plasmids. The K. pneumoniae KP32558 was identified as a pan-drug resistant bacteria, belonging to ST656, and harbored plasmid-encoded blaNDM-5 and mcr-8.2 genes. The blaNDM-5 gene was located on an IncX3 type plasmid. The mcr-8.2 gene was located on a conjugative plasmid pKP32558-2-mcr8, which had a common ancestor with another two mcr-8.2-carrying plasmids pMCR8_020135 and pMCR8_095845. The MIC of KP32558 for colistin was 256 mg/L. The mcr-8.2 gene and mutations in the two-component system, pmrA and crrB, and the regulator mgrB, had a synergistic effect on the high-level colistin resistance. The truncation in the acrR gene, related to tigecycline resistance, was also identified. K. pneumoniae has evolved a variety of complex resistance mechanisms to the last-resort antimicrobials, close surveillance is urgently needed to monitor the prevalence of this clone.

Outbreak of IncX8 Plasmid-Mediated KPC-3-Producing Enterobacterales Infection, China

Carbapenem-resistant Enterobacterales (CRE) infection is highly endemic in China; Klebsiella pneumoniae carbapenemase (KPC) 2-producing CRE is the most common, whereas KPC-3-producing CRE is rare. We report an outbreak of KPC-3-producing Enterobacterales infection in China. During August 2020-June 2021, 25 bla_KPC-3-positive Enterobacteriale isolates were detected from 24 patients in China. Whole-genome sequencing analysis revealed that the bla_KPC-3 genes were harbored by IncX8 plasmids. The outbreak involved clonal expansion of KPC-3-producing Serratia marcescens and transmission of bla_KPC-3 plasmids across different species. The bla_KPC-3 plasmids demonstrated high conjugation frequencies (10^-3 to 10^-4). A Galleria mellonella infection model showed that 2 sequence type 65 K2 K. pneumoniae strains containing bla_KPC-3 plasmids were highly virulent. A ceftazidime/avibactam in vitro selection assay indicated that the KPC-3-producing strains can readily develop resistance. The spread of bla_KPC-3-harboring IncX8 plasmids and these KPC-3 strains should be closely monitored in China and globally.

Two Phenotypes of Klebsiella pneumoniae ST147 Outbreak from Neonatal Sepsis with a Slight Increase in Virulence

Purpose

Severe infection has been the leading causes of neonatal death, especially the emergency of multidrug-resistant bacteria such as carbapenem-resistant Enterobacteriaceae. This study aimed to investigate the outbreak of carbapenem-resistant Klebsiella pneumoniae (CR-KP) in neonatal wards and to explore the possible pathogenesis of Klebsiella pneumoniae.

Materials and Methods

CR-KP were collected from neonatal ward of Chongqing Health Center for Women and Children between 2017 and 2019. Broth microdilution method was used to evaluate the antimicrobial activities in vitro, at the same time, the virulence of the strain was evaluated by in vitro and in vivo experiments. At last, prokaryotic chain specific transcriptome sequencing was conducted to explore the possible pathogenesis of CR-KP.

Results

In this study, a total of 14 carbapenem-resistant-Klebsiella pneumoniae (CR-KP) strains were isolated from Chongqing Health Center for Women and Children, among which all CR-KP isolates were identified as NDM-1-producers. Molecular epidemiological studies revealed ST147 being the most common sequence type (ST). Moreover, we first found two phenotypes of K. pneumoniae with different virulence from the same specimen. Type I, which was a white and sticky colony had a slight increase in virulence with higher biofilm formation, serum resistance and virulence than Type II with gray colony. Compared with the Type II, 10 pathways were obviously changed in Type I especially amino acid metabolism, such as arginine and proline metabolism.

Conclusion

Our findings revealed a new potential threat of NDM-1-positive CR-KP with higher virulence in neonatal ICU ward. We found two phenotypes of K. pneumoniae with different virulent, which may be due to the difference expression of arginine and proline metabolism.

Structural Diversity, Fitness Cost, and Stability of a BlaNDM-1-Bearing Cointegrate Plasmid in Klebsiella pneumoniae and Escherichia coli

Cointegrate/hybrid plasmids combine the genetic elements of two or more plasmids and generally carry abundant antimicrobial resistance determinants. Hence, the spread of cointegrate plasmids will accelerate the transmission of AMR genes. To evaluate the transmission risk caused by cointegrate plasmids, we investigated the structural diversity, fitness cost, and stability of a cointegrate plasmid in Klebsiella pneumoniae YZ6 and Escherichia coli EC600. The cointegrate plasmid pSL131_IncA/C_IncX3 was from a clinical Salmonella Lomita strain. After transferring the plasmid into E. coli EC600 by conjugation, we observed plasmids with different structures, including a full-length original plasmid and two truncated versions. By contrast, DNA fragment deletion and bla_CTX-M-14 gene insertion in the plasmid were detected in a transconjugant derived from K. pneumoniae YZ6. These results suggest that the structure of the plasmid was unstable during conjugation. Furthermore, both the full-length plasmid in EC600 and the structurally reorganized plasmid in YZ6 imposed a fitness cost on the bacterial host and enhanced biofilm formation ability. Serial passaging in antibiotic-free medium resulted in a rapid decline of the plasmid in YZ6. However, the stability of the structurally reorganized plasmid in YZ6 was improved via serial passaging in antibiotic-containing medium. SNP calling revealed that mutations of the outer membrane porin may play an essential role in this process. These findings indicate that structural versatility could contribute to the dissemination of cointegrate plasmids. Although the plasmid incurred a fitness cost in other Enterobacteriaceae species, positive selection could alleviate the adverse effects.