Microbiology Spectrum
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2022
·Vol. 10
·期 6
·
IF 9.043
Shuyi Wang,Qi Ding,Yawei Zhang,Anru Zhang,Qi Wang,Ruobing Wang,Xiaojuan Wang,Longyang Jin,Shuai Ma,Hui Wang
Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) is recognized as a threat worldwide, but the mechanisms underlying its emergence remain unclear. As most CR-hvKP isolates are not hypermucoviscous, we speculated that the evolution of the capsule might result in the convergence of carbapenem resistance and hypervirulence. Here, 2,096 K. pneumoniae isolates were retrospectively collected to screen the ST23-K1 clone, and hypervirulence was roughly defined as being highly resistant to serum killing. The effect of wcaJ on the capsule, virulence, fitness, and resistance acquisition was further analyzed. The capsule gene wcaJ, inserted by ISKpn26/ISKpn74, was identified via whole-genome sequencing in four hvKP, but not hypermucoviscous, isolates. Uronic acid quantitation results revealed that these isolates produced significantly less capsular polysaccharides than NTUH-K2044. A significant increase in capsular production was observed in wcaJ-complemented isolates and confirmed by transmission electron microscopy. Further, all wcaJ-complemented isolates acquired greater resistance to macrophage phagocytosis, and one representative isolate resulted in a significantly higher mortality rate than the parental isolate in mice, indicating that wcaJ inactivation might compromise virulence. However, isolates with wcaJ interruption demonstrated a lower fitness cost and a high conjugation frequency of the blaKPC-2 plasmid, raising concerns about the emergence of carbapenem resistance in hvKP.IMPORTANCE Klebsiella pneumoniae is one of the most common nosocomial pathogens worldwide, and we speculated that the evolution of the capsule might result in the convergence of carbapenem resistance and hypervirulence of K. pneumoniae. The wcaJ gene was first reported to be interrupted by insertion sequence elements in ST23-K1 hypervirulent Klebsiella pneumoniae, resulting in little capsule synthesis, which plays an important role in virulence. We examined the effect of wcaJ on the capsule, virulence, and fitness. Isolates with wcaJ interruption might compromise virulence and demonstrated a lower fitness cost and a high conjugation frequency of the blaKPC-2 plasmid, highlighting its role as a potential factor facilitating hypervirulence and carbapenem resistance.
研究领域:
微生物学
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感染病学
·
基因组学
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DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2025
·
IF 6.7
Dumei Ma,Yongqi Wang,Jiacheng Ye,Chao Xin,Chuan-Fan Ding,Yinghua Yan
Carbapenem resistance and hypervirulence represent two distinct evolutionary pathways in Klebsiella pneumoniae, posing significant challenges in clinical settings. Of particular concern are convergent strains that combine both traits, complicating timely diagnosis and treatment. Herein, we present a novel MOF-derived bimetallic nanocube hybrid nanosheet (denoted Pt-G@Cu5Zn8C@Au) designed to enhance laser desorption/ionization mass spectrometry (LDI-MS) in distinguishing convergent strains from other variants. The novel material, synthesized through the pyrolysis of pristine MOFs, features uniformly distributed Cu and Zn synergistic metal sites within the carbon matrix, addressing critical limitations of current nanomatrices for in situ extraction of metabolic fingerprints from microbial cells, such as limited sensitivity (e.g., amorphous silicon, TiO2, and metal nanoparticles) or relatively weak conductivity and stability (MOF-based materials). Utilizing this advanced matrix, the metabolic fingerprints of 248 K. pneumoniae isolates were rapidly extracted, identifying 23 top VIP-score peaks as potential biomarkers for differentiating convergent strains from their variants. Combined with machine learning, the prediction model achieved 100% accuracy in distinguishing convergent strains from carbapenem-sensitive isolates (CS_cKP) or hypervirulent isolates (hvKP) using the SVM model, while achieving 78.26% accuracy in differentiating them from carbapenem-resistant isolates (CR_cKP) with the KNN/NB models. These findings highlight the high accuracy and efficacy of our assay in distinguishing convergent strains from their variants.
研究领域:
微生物学
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医学诊断
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材料科学
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产品关联
DOI
PubMed
高影响因子
Frontiers in Microbiology
·
2023
·
IF 5.2
Tang Miran,Huang Zeyu,Zhang Xiaodong,Kong Jingchun,Zhou Beibei,Han Yijia,Zhang Yi,Chen Lijiang,Zhou Tieli
Introduction: Phage is promising for the treatment of hypervirulent Klebsiella pneumoniae (hvKP) infections. Although phage resistance seems inevitable, we found that there still was optimization space in phage therapy for hvKP infection.Methods: The clinical isolate K. pneumoniae FK1979 was used to recover the lysis phage ΦFK1979 from hospital sewage. Phage-resistant bacteria were obtained on LB agar and used to isolate phages from sewage. The plaque assay, transmission electron microscopy (TEM), multiplicity of infection test, one-step growth curve assay, and genome analysis were performed to characterize the phages. Colony morphology, precipitation test and scanning electron microscope were used to characterize the bacteria. The absorption test, spot test and efficiency of plating (EOP) assay were used to identify the sensitivity of bacteria to phages. Whole genome sequencing (WGS) was used to identify gene mutations of phage-resistant bacteria. The gene expression levels were detected by RT-qPCR. Genes knockout and complementation of the mutant genes were performed. The change of capsules was detected by capsule quantification and TEM. The growth kinetics, serum resistance, biofilm formation, adhesion and invasion to A549 and RAW 264.7 cells, as well as G. mellonella and mice infection models, were used to evaluate the fitness and virulence of bacteria.Results and discussion: Here, we demonstrated that K2 capsule type sequence type 86 hvKP FK1979, one of the main pandemic lineages of hvKP with thick capsule, rapidly developed resistance to a K2-specific lysis phage ΦFK1979 which was well-studied in this work to possess polysaccharide depolymerase. The phage-resistant mutants showed a marked decrease in capsule expression. WGS revealed single nucleotide polymorphism (SNP) in genes encoding RfaH, galU, sugar glycosyltransferase, and polysaccharide deacetylase family protein in the mutants. RfaH and galU were further identified as being required for capsule production and phage sensitivity. Expressions of genes involved in the biosynthesis or regulation of capsule and/or lipopolysaccharide significantly decreased in the mutants. Despite the rapid and frequent development of phage resistance being a disadvantage, the attenuation of virulence and fitness in vitro and in vivo indicated that phage-resistant mutants of hvKP were more susceptible to the immunity system. Interestingly, the newly isolated phages targeting mutants changed significantly in their plaque and virus particle morphology. Their genomes were much larger than and significantly different from that of ΦFK1979. They possessed much more functional proteins and strikingly broader host spectrums than ΦFK1979. Our study suggests that K2-specific phage has the potential to function as an antivirulence agent, or a part of phage cocktails combined with phages targeting phage-resistant bacteria, against hvKP-relevant infections.
研究领域:
微生物学
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分子生物学
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传染病学
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基因组学
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噬菌体疗法
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产品关联
DOI
PubMed
高影响因子
CURRENT MICROBIOLOGY
·
2025
·Vol. 82
·期 10
·1-12
·
IF 2.6
Bi Jinli,Huang Xin,Meng Liqin,Li Jinghan,He Yu,Jin Jing,Li Taijie
Hypervirulent Klebsiella pneumoniae (hvKP) possesses multiple virulence factors and causes severe infections with elevated mortality rates. It induces a strong inflammatory response in the host, with macrophages playing a key role in defense and inflammation. However, the signaling pathways of macrophages involved in response to hvKP infection remain unclear. In this study, we developed a stable hvKP infection model in differentiated THP-1 macrophages, confirmed by CFU assay and LDH cytotoxicity assay, and subsequently performed transcriptomic profiling analysis of hvKP-infected cells to characterize infection-induced gene expression changes. Pathway and differential gene correlation network analyses identified 14 potential regulatory genes primarily involved in inflammation. These changes in gene expression were further validated by Reverse transcription quantitative PCR (RT-qPCR). KEGG and GO analyses revealed several key signaling pathways involved in inflammation and immune response, particularly the TNF, IL-17, NF-κB, and JAK-STAT pathways. Further analysis indicated that the NF-κB signaling pathway plays a central role in the inflammatory response to hvKP infection, whereas the TNF and IL-17 pathways act synergistically to upregulate pro-inflammatory cytokines and chemokines. Western blot analysis confirmed the expression of TRAF6 and NF-κB p65 protein during hvKP infection. This study provides valuable insights into the molecular mechanisms of macrophage responses to hvKP, offering potential targets for therapeutic intervention.
研究领域:
微生物学
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免疫学
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分子生物学
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传染病学
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基因组学
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细胞生物学
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生物信息学
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产品关联
DOI
PubMed
高影响因子
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