Dataset Information

Whole-Genome-Sequencing characterization of bloodstream infection-causing hypervirulent Klebsiella pneumoniae of capsular serotype K2 and ST374.

ABSTRACT: Hypervirulent K. pneumoniae variants (hvKP) have been increasingly reported worldwide, causing metastasis of severe infections such as liver abscesses and bacteremia. The capsular serotype K2 hvKP strains show diverse multi-locus sequence types (MLSTs), but with limited genetics and virulence information. In this study, we report a hypermucoviscous K. pneumoniae strain, RJF293, isolated from a human bloodstream sample in a Chinese hospital. It caused a metastatic infection and fatal septic shock in a critical patient. The microbiological features and genetic background were investigated with multiple approaches. The Strain RJF293 was determined to be multilocis sequence type (ST) 374 and serotype K2, displayed a median lethal dose (LD50) of 1.5 × 102 CFU in BALB/c mice and was as virulent as the ST23 K1 serotype hvKP strain NTUH-K2044 in a mouse lethality assay. Whole genome sequencing revealed that the RJF293 genome codes for 32 putative virulence factors and exhibits a unique presence/absence pattern in comparison to the other 105 completely sequenced K. pneumoniae genomes. Whole genome SNP-based phylogenetic analysis revealed that strain RJF293 formed a single clade, distant from those containing either ST66 or ST86 hvKP. Compared to the other sequenced hvKP chromosomes, RJF293 contains several strain-variable regions, including one prophage, one ICEKp1 family integrative and conjugative element and six large genomic islands. The sequencing of the first complete genome of an ST374 K2 hvKP clinical strain should reinforce our understanding of the epidemiology and virulence mechanisms of this bloodstream infection-causing hvKP with clinical significance.

SUBMITTER: Wang X

PROVIDER: S-EPMC5955473 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Whole-Genome-Sequencing characterization of bloodstream infection-causing hypervirulent Klebsiella pneumoniae of capsular serotype K2 and ST374.

Wang Xiaoli X Xie Yingzhou Y Li Gang G Liu Jialin J Li Xiaobin X Tian Lijun L Sun Jingyong J Ou Hong-Yu HY Qu Hongping H

Virulence 20180101 1

Hypervirulent K. pneumoniae variants (hvKP) have been increasingly reported worldwide, causing metastasis of severe infections such as liver abscesses and bacteremia. The capsular serotype K2 hvKP strains show diverse multi-locus sequence types (MLSTs), but with limited genetics and virulence information. In this study, we report a hypermucoviscous K. pneumoniae strain, RJF293, isolated from a human bloodstream sample in a Chinese hospital. It caused a metastatic infection and fatal septic shock ...[more]

PMID: 29338592

Similar Datasets

Project description:Klebsiella pneumoniae is a major cause of neonatal sepsis. Hypervirulent Klebsiella pneumoniae (hvKP) that cause invasive infections and/or carbapenem-resistant hvKP (CR-hvKP) limit therapeutic options. Such strains causing neonatal sepsis have rarely been studied. Characterization of neonatal septicemic hvKP/CR-hvKP strains in terms of resistance and virulence was carried out. Antibiotic susceptibility, molecular characterization, evaluation of clonality, in vitro virulence, and transmissibility of carbapenemase genes were evaluated. Whole-genome sequencing (WGS) and mouse lethality assays were performed on strains harboring pLVPK-associated markers. About one-fourth (26%, 28/107) of the studied strains, leading to mortality in 39% (11/28) of the infected neonates, were categorized as hvKP. hvKP-K2 was the prevalent pathotype (64.2%, 18/28), but K54 and K57 were also identified. Most strains were clonally diverse belonging to 12 sequence types, of which ST14 was most common. Majority of hvKPs possessed virulence determinants, strong biofilm-forming, and high serum resistance ability. Nine hvKPs were carbapenem-resistant, harboring blaNDM-1/blaNDM-5 on conjugative plasmids of different replicon types. Two NDM-1-producing high-risk clones, ST11 and ST15, had pLVPK-associated markers (rmpA, rmpA2, iroBCDEN, iucABCDiutA, and peg-344), of which one co-transferred the markers along with blaNDM-1. The 2 strains revealed high inter-genomic resemblance with the other hvKP reference genomes, and were lethal in mouse model. To the best of our knowledge, this study is the first to report on the NDM-1-producing hvKP ST11-K2 and ST15-K54 strains causing fatal neonatal sepsis. The presence of pLVPK-associated markers and blaNDM-1 in high-risk clones, and the co-transmission of these genes via conjugation calls for surveillance of these strains. IMPORTANCE Klebsiella pneumoniae is a leading cause of sepsis in newborns and adults. Among the 2 major pathotypes of K. pneumoniae, classical (cKP) and hypervirulent (hvKP), hvKP causes community-acquired severe fatal invasive infections in even healthy individuals, as it possesses several virulence factors. The lack of comprehensive studies on neonatal septicemic hvKPs prompted this work. Nearly 26% diverse hvKP strains were recovered possessing several resistance and virulence determinants. The majority of them exhibited strong biofilm-forming and high serum resistance ability. Nine of these strains were also carbapenem (last-resort antibiotic)-resistant, of which 2 high-risk clones (ST11-K2 and ST15-K54) harbored markers (pLVPK) noted for their virulence, and were lethal in the mouse model. Genome-level characterization of the high-risk clones showed resemblance with the other hvKP reference genomes. The presence of transmissible carbapenem-resistant gene, blaNDM, along with pLVPK-markers calls for vigilance, as most clinical microbiology laboratories do not test for them.

Project description:Hypervirulent Klebsiella pneumoniae with capsular polysaccharides (CPSs) causes severe nosocomial- and community-acquired infections. Phage-derived depolymerases can degrade CPSs from K. pneumoniae to attenuate bacterial virulence, but their antimicrobial mechanisms and clinical potential are not well understood. In the present study, Klebsiella phage GH-K3-derived depolymerase Depo32 (encoded by gene gp32) was identified to exhibit high efficiency in specifically degrading the CPSs of K2 serotype K. pneumoniae. The cryo-electron microscopy structure of trimeric Depo32 at a resolution up to 2.32 Å revealed potential catalytic centers in the cleft of each of the two adjacent subunits. K. pneumoniae subjected to Depo32 became more sensitive to phagocytosis by RAW264.7 cells and activated the cells by the mitogen-activated protein kinase signaling pathway. In addition, intranasal inoculation with Depo32 (a single dose of 200 µg, 20 µg daily for 3 days, or in combination with gentamicin) rescued all C57BL/6J mice infected with a lethal dose of K. pneumoniae K7 without interference from its neutralizing antibody. In summary, this work elaborates on the mechanism by which Depo32 targets the degradation of K2 serotype CPSs and its potential as an antivirulence agent. IMPORTANCE Depolymerases specific to more than 20 serotypes of Klebsiella spp. have been identified, but most studies only evaluated the single-dose treatment of depolymerases with relatively simple clinical evaluation indices and did not reveal the anti-infection mechanism of these depolymerases in depth. On the basis of determining the biological characteristics, the structure of Depo32 was analyzed by cryo-electron microscopy, and the potential active center was further identified. In addition, the effects of Depo32 on macrophage phagocytosis, signaling pathway activation, and serum killing were revealed, and the efficacy of the depolymerase (single treatment, multiple treatments, or in combination with gentamicin) against acute pneumonia caused by Klebsiella pneumoniae was evaluated. Moreover, the roles of the active sites of Depo32 were also elucidated in the in vitro and in vivo studies. Therefore, through structural biology, cell biology, and in vivo experiments, this study demonstrated the mechanism by which Depo32 targets K2 serotype K. pneumoniae infection.

Project description:The genomic organization of the chromosomal cps region that is responsible for capsular polysaccharide synthesis in Klebsiella pneumoniae Chedid (O1:K2) was investigated. Deletion analyses and Southern hybridization studies suggested that the central region of the cloned 29-kb BamHI fragment is indispensable for K2 capsular polysaccharide synthesis. The 24,329-bp nucleotide sequence of the Klebsiella cps region was determined and deposited in the EMBL and GenBank databases through DDBJ and assigned accession number D21242. Nineteen possible open reading frames (ORFs) were identified in the sequenced area. Among them, 13 ORFs are very close to each other. Six of the 19 ORFs show considerable nucleotide sequence similarities to Salmonella typhimurium cpsG, cpsB, rfbP, and orf2.8, Escherichia coli gnd, and Haemophilus influenzae bexD, respectively. Moreover, the deduced amino acid sequence of the ORF10 product demonstrated a highly hydrophobic profile and showed putative membrane topology similarity to Rickettsia prowazekii ATP/ADP translocase. Nucleotide sequence similar to the sigma 54-dependent promoter, as well as the usual -35 and -10 sequences, were identified just upstream of ORF3, which is the first ORF in the polycistronic structure. Furthermore, a sequence (GGGCGGTAGCGT) found just downstream of the sigma 54-dependent promoter-like sequence was generally conserved among gene clusters implicated in cell surface polysaccharide synthesis, such as Salmonella rfb and viaB and E. coli kpsMT and rfaQPG. A possible transcriptional terminator with a hairpin loop structure found just downstream of ORF15 that is a homolog of E. coli gnd. K2 capsular polsaccharide biosynthesis in E. coli K-12 depends on cpsB (mannose-1-phosphate guanyltransferase gene), and Klebsiella cpsB, found in the downstream region of the polycistronic structure, was able to complement cpsB of E. coli. Results of transposon insertion and promoter-cloning analyses were consistent with the results of nucleotide sequence analysis.

Project description:Hypervirulent Klebsiella pneumoniae (hvKp) is a variant that has been increasingly linked to severe, life-threatening infections including pyogenic liver abscess and bloodstream infections. HvKps belonging to the capsular serotypes K1 and K2 have been reported worldwide, however, very scarce studies are available on their genomics and virulence. In the current study, we report four hypermucoviscous extended-spectrum β-lactamase-producing hvKp clinical strains of capsular serotype K1 and K2 isolated from pus and urine of critically ill patients in tertiary care hospitals in Oman. These strains belong to diverse sequence types (STs), namely ST-23(K1), ST-231(K2), ST-881(K2), and ST-14(K2). To study their virulence, a Galleria mellonella model and resistance to human serum killing were used. The G. mellonella model revealed that the K1/ST-23 isolate was the most virulent, as 50% of the larvae died in the first day, followed by isolate K2/ST-231 and K2/ST-14, for which 75% and 50% of the larvae died in the second day, respectively. Resistance to human serum killing showed there was complete inhibition of bacterial growth of all four isolates by the end of the first hour and up to the third hour. Whole genome sequencing (WGS) revealed that hvKp strains display a unique genetic arrangement of k-loci. Whole-genome single-nucleotide polymorphism-based phylogenetic analysis revealed that these hvKp isolates were phylogenetically distinct, belonging to diverse clades, and belonged to different STs in comparison to global isolates. For ST-23(K1), ST-231(K2), ST-881(K2), and ST-14(K2), there was a gradual decrease in the number of colonies up to the second to third hour, which indicates neutralization of bacterial cells by the serum components. However, this was followed by a sudden increase of bacterial growth, indicating possible resistance of bacteria against human serum bactericidal activity. This is the first report from Oman detailing the WGS of hvKp clinical isolates and assessing their resistance and virulence genomics, which reinforce our understanding of their epidemiology and dissemination in clinical settings.

Dataset Information

Whole-Genome-Sequencing characterization of bloodstream infection-causing hypervirulent Klebsiella pneumoniae of capsular serotype K2 and ST374.

Publications

Whole-Genome-Sequencing characterization of bloodstream infection-causing hypervirulent Klebsiella pneumoniae of capsular serotype K2 and ST374.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets