Department of Infectious Diseases, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
Key Laboratory of Microbial Technology and Bioinformatics of Zhejiang Province, Hangzhou, China.
BMC Microbiol. 2018 Aug 29;18(1):94. doi: 10.1186/s12866-018-1236-2.
Hypervirulent Klebsiella pneumoniae (hvKP) is emerging around the Asian-Pacific region and it is the major cause of the community-acquired pyogenic liver abscesses. Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKP) isolates were reported in France, China and Taiwan. However, the international-ally agreed definition for hvKP and the virulence level of hvKP are not clear.
In this study, 56 hvKP isolates were collected from March 2008 to June 2012 and investigated by string test, capsule serotyping, multilocus sequence typing (MLST), virulence gene detection and serum resistance assay. Among the 56 K. pneumoniae isolates, 64.3% had the hypermucoviscosity phenotype, meanwhile, 64.3% were the K1 serotype and 19.6% were the K2 serotype. Within the K1 serotype, 94.4% were ST23, and within the K2 serotype, ST65, ST86 and ST375 accounted for the same percentage 27.3%. The serum resistance showed statistically normal distribution. According to the 50% lethal dose of Galleria. mellonella infection model, hvKP isolates were divided into high virulence level group and moderate virulence level group. The ability of each method evaluating the virulence level of hvKP was assessed using the area under the receiver operating characteristic curve.
K1 ST23 K. pneumoniae was the most prevalent clone of the hvKP. However, K1 ST23 K. pneumoniae was the dominant clone in the moderate virulence level group. MLST was a relatively reliable evaluation method to discriminate the virulence level of hvKP in our study.
产超广谱β-内酰胺酶（ESBL）肺炎克雷伯菌（hvKP）在亚太地区流行，是社区获得性化脓性肝脓肿的主要原因。法国、中国和中国台湾地区均有报道耐多药产超广谱β-内酰胺酶肺炎克雷伯菌（MDR-hvKP）分离株。然而，hvKP 的国际公认定义和 hvKP 的毒力水平尚不清楚。
本研究收集了 2008 年 3 月至 2012 年 6 月的 56 株 hvKP 分离株，通过.string 试验、荚膜血清分型、多位点序列分型（MLST）、毒力基因检测和血清抵抗试验进行分析。在 56 株肺炎克雷伯菌中，64.3%具有高黏液表型，同时 64.3%为 K1 血清型，19.6%为 K2 血清型。在 K1 血清型中，94.4%为 ST23，在 K2 血清型中，ST65、ST86 和 ST375 各占 27.3%。血清抵抗呈统计学正态分布。根据金龟子幼虫半数致死量感染模型，hvKP 分离株分为高毒力水平组和中毒力水平组。使用受试者工作特征曲线下面积评估每种方法评估 hvKP 毒力水平的能力。
K1 ST23 肺炎克雷伯菌是 hvKP 最常见的克隆。然而，K1 ST23 肺炎克雷伯菌是中毒力水平组的优势克隆。MLST 是本研究中区分 hvKP 毒力水平的一种相对可靠的评估方法。
