Development of a diagnostic test for hypervirulent Klebsiella pneumoniae

 描述（由申请方提供）：肺炎克雷伯菌（hvKP）的高毒力致病型的出现和全球传播令人担忧。与通常的医疗保健相关场所的“经典”K。在西方，hvKP在来自社区的年轻健康个体中引起严重的、威胁生命和器官的感染，并且具有从感染部位转移性传播的能力。此外，使这种变异完全可怕的是它获得极端和泛耐药的抗菌素耐药性的潜力，这一现实已经开始。据我们所知，很少有实验室在研究hvKP，在美国也没有。存在许多重大的知识差距。重要的是，缺乏区分hvKP菌株与cKP菌株的可靠且有效的手段。这一缺陷导致了对hvKP的认识不足，阻碍了科学进步，并对患者护理产生了不利影响。将hvKP确定为致病因子将告知临床医生根据需要寻找隐性脓肿进行引流，对眼内炎的发展保持警惕（需要立即使用玻璃体内抗生素和玻璃体切除术），优化成功经皮引流积液的条件（从而避免开放式手术引流），并根据感染部位的需要改变全身性抗菌治疗的性质和持续时间。本提案的目的是鉴定hvKP的特异性基因型和/或表型标记。虽然高粘液粘性表型，定义为一个积极的字符串测试，已被用来区分hvKP，这个测试是不是最佳的敏感性或特异性，特别是在较低的hvKP患病率的地区。目前，鉴定hvKP的最可靠的方法是来自非卧床健康宿主中严重感染的临床综合征加上/减去感染的转移性扩散。尽管并非所有感染hvKP的患者都可以以这种方式鉴定（具有共病的患者中的感染也可以用免疫组织化学方法鉴定）。 发生），使用该定义将使得能够产生富含hvKP和富含cKP的菌株群组用于比较研究。来自我们小组和文献的初步数据已经鉴定了基因型标记物（例如iucA（需氧肌动蛋白合成）和我们实验室鉴定的2种新的潜在基因标记物）和表型标记物（动物感染模型中的总铁载体产生和毒力），我们假设这些标记物可以用于可靠和有效地鉴定hvKP。初始 对hvKP富集和cKP富集菌株衍生组群的研究将鉴定最佳标记物，随后将在独立验证组群中对其进行评估。动物数据将用于支持hvKP标志物的特异性和灵敏度，该标志物可实际用于临床微生物学和研究实验室。本提案产生的数据将导致开发一种供临床微生物学和研究实验室使用的检测方法，以可靠有效地识别hvKP。这种能力将使该领域所需的转化进步，最重要的是改善患者护理。

 DESCRIPTION (provided by applicant): The emergence and global dissemination of a hypervirulent pathotype of Klebsiella pneumoniae (hvKP) is concerning. In contrast to the usual healthcare-associated venue for "classical" K. pneumoniae (cKP) infections in the West, hvKP causes serious, life and organ threatening infections in younger, healthy individuals from the community and has the ability to metastatically spread from sites of infection. Further, what makes this variant outright scary is its potential to acquire extreme and pan-resistant antimicrobial resistance, a reality that has already begun. Few laboratories are studying hvKP and none in the US that we are aware of. Many significant knowledge gaps exist. Importantly, a reliable and efficient means to differentiate hvKP strains from cKP strains is lacking. This deficiency has resulted in under-recognition of hvKP, impeded scientific advances, and has adversely affected patient care. Identification of hvKP as the offending agent will inform the clinician to seek out occult abscesses for drainage as needed, maintain vigilance for the development of endophthalmitis (which requires immediate institution of intravitreal antibiotics & vitrectomy), optimize conditions for successful percutaneous drainage of abscesses (and thereby avoid open surgical drainage), and modify the nature and duration of systemic antimicrobial therapy as dictated by site(s) of infection. The objective of this proposal is to identify a specific genotypic and/or phenotypic marker for hvKP. Although a hypermucoviscous phenotype, as defined by a positive string test, has been used to discriminate hvKP, this test is NOT optimally sensitive or specific, especially in regions of lower hvKP prevalence. Presently, the most reliable means to identify hvKP is from the clinical syndrome of serious infection in ambulatory, healthy hosts plus/minus metastatic spread of infection. Although not all patients infected with hvKP can be identified in this manner (infection in patients with co-morbidities also occurs), using this definition will enable the generation of hvKP-rich and cKP-rich strain cohorts for comparative study. Preliminary data from our group and the literature, has identified genotypic markers (e.g. iucA (aerobactin synthesis) and 2 new potential gene markers identified by our lab) and phenotypic markers (total siderophore production and virulence in an animal infection model) that we hypothesize can be used to reliably and efficiently identify hvKP. Initial studies on hvKP-rich and cKP-rich strain derivation cohorts will identify the optimal marker, which will be subsequently assessed in independent validation cohorts. Animal data will be used to support the specificity and sensitivity of an hvKP marker that can be practically employed in both clinical microbiology and research laboratories. Data generated from this proposal will result in the development of a test for use by the clinical microbiology and research laboratories to reliably and efficiently identify hvKP. This ability will enable the needed translational advancs in the field and most importantly improved patient care.