Objectives

This study aimed to retrospectively investigate the epidemiology and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates from neonatal intensive care units (NICU) between 2017 and 2021.

Methods

The antibacterial susceptibility of all strains was assessed using the VITEK 2 compact system. The presence of antibiotic resistance, virulence genes, sequence types (STs), capsular (K) types, and the wzi genes was determined through polymerase chain reaction (PCR). Molecular typing was performed by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme XbaI. Additionally, the virulence potential of peg344-positive strains was evaluated using the string test and mouse intraperitoneal infection models. Whole-genome sequencing was conducted on the DNB system and PacBio platforms.

Results

A total of 46 CRKP isolates were collected during the study period. Out of these, 93.47% (43/46) were identified as CRKP strains belonging to the ST76-K10 type carrying bla_NDM-5. It was observed that CRKP infection resulted in more severe clinical symptoms compared to CRKP colonization. Among the CRKP strains, a hypervirulent CRKP strain called KP-63, belonging to the ST23 type, was identified. This strain exhibited high mortality in the mouse infection model and was found to possess virulence genes. Genomic alignment analysis revealed a significant similarity between the virulence plasmid from KP-63 strain (pKP-63) and pK2044 from the hypervirulent K. pneumoniae strain NTUH-2044.

Conclusions

There has been a potential dissemination of ST76-K10 type CRKP carrying bla_NDM-5 in the NICU at Ningxia Hospital. Neonatal CRKP infection has been found to cause more severe clinical symptoms than colonization. Furthermore, we have discovered a CR-hvKP strain of ST23 with serotype K1, which exhibits a significant resemblance in its virulent plasmid to pK2044. Therefore, it is crucial to enforce effective measures to restrict the spread and hinder the evolution of CRKP within the hospital.

中文翻译：

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2017-2021年宁夏医科大学总医院新生儿重症监护病房分离的耐碳青霉烯类肺炎克雷伯菌流行病学及分子特征分析

目标

本研究旨在回顾性调查2017年至2021年新生儿重症监护病房（NICU）分离的耐碳青霉烯类肺炎克雷伯菌（CRKP）的流行病学和分子特征。

方法

使用 VITEK 2 紧凑系统评估所有菌株的抗菌敏感性。通过聚合酶链式反应 (PCR) 确定抗生素耐药性、毒力基因、序列类型 (ST)、荚膜 (K) 类型和wzi基因的存在。使用限制酶 XbaI 通过脉冲场凝胶电泳 (PFGE) 进行分子分型。另外，使用串线测试和小鼠腹膜内感染模型评估了peg344阳性菌株的毒力潜力。全基因组测序在 DNB 系统和 PacBio 平台上进行。

结果

研究期间总共收集了 46 个 CRKP 分离株。其中，93.47%（43/46）被鉴定为属于携带bla _NDM-5的ST76-K10型CRKP菌株。据观察，与 CRKP 定植相比，CRKP 感染导致更严重的临床症状。在CRKP菌株中，鉴定出一种高毒力CRKP菌株，称为KP-63，属于ST23型。该菌株在小鼠感染模型中表现出高死亡率，并被发现具有毒力基因。基因组比对分析显示，KP-63 菌株 (pKP-63) 的毒力质粒与高毒力肺炎克雷伯菌菌株 NTUH-2044 的 pK2044 之间存在显着相似性。

结论

宁夏医院新生儿重症监护病房中存在携带bla _NDM-5的ST76-K10型CRKP的潜在传播。已发现新生儿 CRKP 感染会导致比定植更严重的临床症状。此外，我们还发现了 ST23 血清型 K1 的 CR-hvKP 菌株，其毒力质粒与 pK2044 显着相似。因此，采取有效措施限制院内CRKP的传播和发展至关重要。