Development of a diagnostic test for hypervirulent Klebsiella pneumoniae

 描述(由申请人提供)：一种超强毒力肺炎克雷伯菌(HvKP)的出现和全球传播令人担忧。与西方通常与医疗保健相关的“经典”肺炎克雷伯菌(CKP)感染场所不同，HvKP会在来自社区的年轻、健康的人中引起严重的、危及生命和器官的感染，并有能力从感染部位转移传播。此外，让这种变种完全可怕的是，它有可能获得极端和泛耐药的抗菌素耐药性，这一现实已经开始。据我们所知，很少有实验室在研究HvKP，美国也没有研究HvKP的实验室。存在许多重大的知识差距。重要的是，缺乏可靠和有效的手段来区分HvKP和CKP菌株。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确定为致病因素将通知临床医生根据需要寻找隐匿性脓肿进行引流，保持对眼内炎的发展的警惕(这需要立即实施玻璃体内抗生素和玻璃体切除术)，优化脓肿经皮引流的条件(从而避免开放手术引流)，并根据感染部位(S)改变全身抗菌治疗的性质和持续时间。这项建议的目的是确定hvKP的一个特定的基因和/或表型标记。尽管如阳性串试验所定义的高粘液表型已被用于鉴别HvKP，但这项试验并不是最佳的敏感性或特异性，尤其是在HvKP患病率较低的地区。目前，确定HvKP最可靠的方法是通过临床综合征，即在健康的门诊宿主中严重感染加上/减少感染的转移扩散。尽管并不是所有感染人类免疫缺陷病毒的患者都能以这种方式被识别(合并感染的患者也 发生)，使用这一定义将能够产生富含HvKP和CKP的菌株队列，用于比较研究。来自我们小组和文献的初步数据，已经确定了我们假设可以用于可靠和有效地识别hvKP的基因标记(例如IUCA(好氧肌动蛋白合成)和我们实验室发现的两个新的潜在基因标记)和表型标记(动物感染模型中的总铁载体产量和毒力)。首字母 对富含hvKP和富含CKP的菌株衍生队列的研究将确定最佳标记，随后将在独立的验证队列中进行评估。动物数据将被用来支持hvKP标记物的特异性和敏感性，该标记物可实际应用于临床微生物学和研究实验室。根据这项提议产生的数据将导致开发一种测试，供临床微生物学和研究实验室使用，以可靠和有效地识别HvKP。这一能力将在该领域实现所需的翻译进步，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.