Understanding hypermucoviscosity in Klebsiella

了解克雷伯氏菌的高粘膜粘稠度

• 批准号: 10442731
• 负责人: VIRGINIA L MILLER
• 金额: $ 44.36万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-16 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10442731
• 关键词: Address; Affect; Antibiotic Resistance; Biological Assay; Carbapenems; Centers for Disease Control and Prevention (U.S.); Characteristics; Clinical; Communities; Complement; Data; Defect; Development; Disease; Enterobacteriaceae; Extended-spectrum β-lactamase; Gene Expression; Genes; Genetic Transcription; Goals; Gram-Negative Bacteria; Immunocompromised Host; In Vitro; Individual; Infection; Klebsiella; Klebsiella pneumoniae; Link; Liver Abscess; Long-Term Care Nursing; Multi-Drug Resistance; Mus; Nosocomial Infections; Operon; Pathogenesis; Phagocytes; Phenotype; Plasmids; Play; Polysaccharides; Prevalence; Production; Property; Proteins; Reporting; Role; Testing; Virulence; Virulence Factors; Work; capsule; carbapenem resistance; carbapenem-resistant Enterobacteriaceae; colistin resistance; diagnostic tool; extracellular; human disease; in vivo; mortality; mouse model; mutant; novel therapeutics; promoter; resistant Klebsiella pneumoniae; resistant strain; targeted treatment

Abstract Klebsiella pneumoniae (Kpn) is a leading cause of Gram-negative nosocomial infections and is associated with a high mortality rate. Antibiotic resistance is a growing issue among the Enterobacteriaceae and of the Enterobacteriaceae Kpn is the most prevalent extended spectrum β-lactamase and carbapenem resistant Enterobacteriaceae isolate. The increasing prevalence of antibiotic-resistant Kpn only serves to compound its clinical importance and to complicate treatment options. Capsule has been established as a key virulence factor and is this species best studied virulence factor. Kpn strains are broadly classified as hypervirulent (hv) or classical, with hv strains typically causing community acquired liver abscess and invasive infections. Classical strains are more typically associated with nosocomial infections. The hv strains have a hypermucoviscous (HMV) phenotype thought to be due to over-production of capsule and have acquired rmpA that contributes to increased capsule (cps) gene expression. Most classical strains, including recent clinical isolates associated with carbapenem resistance (ST258) are not HMV, do not have the rmpA gene and are not virulent in mouse models of infection. Recent reports of these multidrug resistant strains acquiring the HMV phenotype is of significant concern and amplifies the need to understand what HMV is, how it is produced and how it contributes to virulence. Despite the apparent association between HMV and over-production of capsule, what causes the HMV phenotype and its relationship to capsule production is not known. Recent work from our lab using the HMV strain KPPR1S has shown that deletion of rmpA causes decreases in expression from cps promoters, and reduction (but not complete loss) in both capsule production and HMV. In addition, we found that rmpA is the first gene of an operon (rmpADC) and that RmpA positively regulates expression of the operon. Results from analysis of a complete deletion of the operon with the individual genes indicates that from this locus, RmpA primarily is required for expression of the operon, that only RmpC is necessary for expression of cps genes, and that only RmpD is necessary for HMV. Consistent with this, a mutant lacking only rmpD retains WT levels of cps gene expression, capsule production and is HMV negative. The rmpD mutant is the first mutant identified that separates HMV from the over- production of capsule, and the phenotype of the strain only expressing rmpC indicates that over- production of capsule alone is not sufficient for HMV. Due to the importance of HMV to the virulence of hv Kpn strains, the potential for classical strains to acquire HMV, the incomplete picture of what constitutes HMV and what is required to produce HMV, we propose to a) gain a better understanding of RmpD, (b) characterize the interacting partners of RmpD and how they affect HMV, and determine the composition of the HMV exopolysaccharide, and (c) examine how HMV contributes to virulence.

抽象的 肺炎克雷伯氏菌（KPN）是革兰氏阴性症医院感染的主要原因，与之相关 死亡率高。抗生素耐药性是肠杆菌科和 肠杆菌科KPN是最普遍的扩展光谱β-内酰胺酶和碳青霉烯抗性 肠杆菌科。抗生素耐药性KPN的患病率的增加仅使其复杂化 临床重要性和使治疗选择复杂化。胶囊已成为关键病毒 因素，这是该物种最好研究的病毒因子。 KPN菌株被广泛归类为HyperVirus（HV） 或经典，HV菌株通常会导致社区获得的肝脓肿和侵袭性感染。 经典菌株通常与医院感染有关。 HV菌株有一个 高效果（HMV）表型被认为是由于胶囊过量产生的，并且已获得RMPA 这有助于增加胶囊（CPS）基因表达。大多数古典菌株，包括最近的临床 与碳青霉苯抗性相关的分离株（ST258）不是HMV，没有RMPA基因，也不是 在感染的小鼠模型中有力。最近关于这些多药抗性应变的报道 HMV表型引起了重大关注，放大器需要了解HMV是什么，它是如何的 产生及其对病毒的贡献。尽管HMV和 胶囊过量产生，导致HMV表型及其与胶囊的关系 生产尚不清楚。使用HMV菌株KPPR1S的最新工作表明删除 RMPA导致CPS启动子的表达下降，并且两者都会减少（但不是完全损失） 胶囊生产和HMV。此外，我们发现RMPA是操作系统的第一个基因（RMPADC）和 RMPA积极调节歌剧的表达。分析完全删除的结果 带有各个基因的歌剧表明，从该基因座，RMPA主要是表达的 歌剧，仅RMPC对于表达CPS基因是必需的，而HMV仅需要RMPD。 与此相一致，仅缺乏RMPD的突变体保留WT水平的CPS基因表达，胶囊产生 并为HMV负。 RMPD突变体是第一个突变体，该突变体将HMV与过度分离 胶囊的产生，仅表达RMPC的菌株的表型表明过度 仅胶囊的产生不足以用于HMV。由于HMV对HV病毒的重要性 KPN菌株是获得HMV的经典菌株的潜力，这是构成HMV的不完整图片 以及生产HMV所需的内容，我们建议a）更好地了解RMPD，（b）表征 RMPD的相互作用伙伴及其如何影响HMV，并确定HMV的组成 外多糖和（c）检查HMV如何对病毒贡献。