新型超广谱β-内酰胺酶PME耐药传播分子机制

Extended-spectrum beta-lactamases (ESBLs) is the most important rival in clinical antibiotic treatment of infection.We preliminary reported a new class of ESBLs PME, and confirmed that PME has been local epidemic with 6.2% relevance ratio in China. But the resistance molecular mechanism of transmission of PME is not clear. The objective of this study was to investigate the molecular epidemiology of PME-producing multidrug resistant clinical isolates in China, with a focus on clarifying the resistance transmission mechanisms of PME. In this project, characterization and resistance transmission mechanisms of PME are used to confirm from different levels using MLST, plasmid conjugation and transformation, pulsed field gel electrophoresis (PFGE), plasmid profiling, S1-PFGE (PFGE with S1 nuclease digestion), southern hybridization, enzyme kinetics, molecular modeling, crystal structure etc. The achievement of this project has a very important theoretical and practical significance.

超广谱β-内酰胺酶(ESBLs)一直是临床抗菌药物感染治疗最主要"对手"。申请人前期发现并报道了一种全新类型ESBL PME；对全国3省7家医院1482株产ESBL菌株监测发现PME已在这些地区流行，检出率达6.2%，且8.7%PME阳性病例因感染而死亡，提示PME很可能成为下一个"超级细菌"危害人类健康。进一步预实验显示产PME菌株间部分同源，blaPME基因周边序列含整合子和插入序列，质粒酶切图谱呈现多样性，提示：染色体、质粒和整合子等耐药移动元件的联合作用影响着PME耐药传播，但确切的耐药传播分子机制有待深入研究。据此，本项目拟以全国PME耐药分子流行病学为切入点，通过全基因组测序、PFGE、质粒酶切图谱、核酸杂交、S1-PFGE、酶动力学和晶体结构等技术和方法，旨在从染色体、质粒和PME酶学特性等各层面阐明PME耐药传播分子机制，为PME疫情监控和指导临床用药提供科学依据。

本项目以项目主持人前期发现并报道的一种全新类型超广谱β-内酰胺酶(ESBLs) PME为对象，阐明了全国PME耐药分子流行病学，证实了PME已在我国局部流行，且出现了2种新亚型PME-2和PME-3。产PME菌株脉冲场凝胶电泳和多位点序列分型（MLST）、以及blaPME基因周边序列和质粒酶切图谱实验结果表明，染色体、质粒和整合子等耐药移动元件的联合介导影响着PME耐药传播。此外，项目还揭示PME关键氨基酸的突变对其水解抗菌耐药能力有明显影响。本项目实验材料来自于临床，做到研究成果直接服务于临床，为PME的监测和控制提供科学依据。