Identification of Capsular Types in Carbapenem-Resistant Klebsiella pneumoniae Strains by wzc Sequencing and Implications for Capsule Depolymerase Treatment
Identification of Capsular Types in Carbapenem-Resistant Klebsiella pneumoniae Strains by wzc Sequencing and Implications for Capsule Depolymerase Treatment
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DOI：
10.1128/aac.03560-14
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发表时间：
2015-02-01
影响因子：
4.9
通讯作者：
Wang, Jin-Town
中科院分区：
文献类型：
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作者：
Pan, Yi-Jiun;Lin, Tzu-Lung;Wang, Jin-Town
肺炎克雷伯菌是一种与多种疾病相关的重要人类病原体，耐多药肺炎克雷伯菌（MDRKP）的流行正在迅速增加。本文采用wzc测序法对85株耐碳青霉烯肺炎克雷伯菌（CRKP）的荚膜类型进行了鉴定，并研究了CRKP菌株中碳青霉烯酶和整合子的存在情况。10株（12%）CRKP碳青霉烯酶阳性（亚胺青霉烯酶，6/85株；肺炎克雷伯菌碳青霉烯酶，3/85株；维罗纳整合子编码金属β -内酰胺酶，1/85株）。荚膜型K64占32株（38%），其次是K62（13%）、K24（8%）、KN2（7%）和K28（6%）。通过多位点序列分型（multilocus Sequence typing， MLST）确定序列类型（STs），结果表明ST11为主要st，占这些CRKP菌株（40/85株）的47%。我们进一步分离出K64特异性荚膜解聚合酶（K64dep），该酶能增强体外接种K64肺炎克雷普菌小鼠的血清和中性粒细胞杀伤，提高其存活率。毒性研究表明，经K64dep处理的小鼠生化指标正常，肝、肾、脾组织病理变化不明显，说明酶处理对小鼠无毒性作用。因此，CRKP菌株之间荚膜型聚类的发现以及MDRKP感染的荚膜解聚合酶的有效治疗对基于荚膜的疫苗开发和治疗具有重要意义。
Klebsiella pneumoniae is an important human pathogen associated with a variety of diseases, and the prevalence of multidrug-resistant K. pneumoniae (MDRKP) is rapidly increasing. Here we determined the capsular types of 85 carbapenem-resistant K. pneumoniae (CRKP) strains by wzc sequencing and investigated the presence of carbapenemases and integrons among CRKP strains. Ten CRKP strains (12%) were positive for carbapenemase (imipenemase, 6/85 strains; K. pneumoniae carbapenemase, 3/85 strains; Verona integron-encoded metallo-beta-lactamase, 1/85 strains). Capsular type K64 accounted for 32 CRKP strains (38%), followed by K62 (13%), K24 (8%), KN2 (7%), and K28 (6%). Sequence types (STs) were determined by multilocus sequence typing (MLST), and the results indicated that ST11, which accounted for 47% of these CRKP strains (40/85 strains), was the major ST. We further isolated a K64-specific capsule depolymerase (K64dep), which could enhance serum and neutrophil killing in vitro and increase survival rates for K64 K. pneumoniae-inoculated mice. The toxicity study demonstrated that mice treated with K64dep showed normal biochemical parameters and no significant histopathological changes of liver, kidney, and spleen, indicating that enzyme treatment did not cause toxicity in mice. Therefore, the findings of capsular type clustering among CRKP strains and effective treatment with capsule depolymerase for MDRKP infections are important for capsule-based vaccine development and therapy.