VanM基因阳性屎肠球菌分子生物学特征以及临床感染控制的研究

发布时间：2018-03-05 11:08

  本文选题：vanM　切入点：万古霉素耐药屎肠球菌　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：目的:本研究通过分析一位新型vanM基因阳性耐万古霉素屎肠球菌(VRE)血流感染患者的临床表现,临床及周围环境45株vanM基因阳性屎肠球菌的分子生物学特征,有助于进一步认识这种新型vanM型耐万古霉素肠球菌感染的特征及相关的预防治疗措施。方法:收集和分析患者的临床资料,按照我国2012年发布的医院消毒卫生标准,进行周围环境采样、送检培养。送检的标本做了以下的检测:MALDI-TOFMS确定分离菌株为屎肠球菌。E-test法测定8种抗生素对屎肠球菌的最小抑菌浓度(MIC)。脉冲场凝胶电泳(PFGE)和多位点序列分析(MLST)确定菌株之间的同源性。多重聚合酶链反应(PCR)检测万古霉素屎肠球菌耐药基因及毒力基因。质粒接合试验验证vanM基因是否可以转移。根据结果分析比较临床和环境菌株的分子生物学特征。同时,院感科为预防该基因型耐药菌株进一步传播,对该感染患者进行接触隔离并对患者周围环境进行严格消毒。结果:一位51岁男性患者因为反复头痛和肢体活动障碍入院。头颅磁共振(MRI)检查提示脑脓肿。患者在立体定向穿刺引流术后转入我院中心监护室(ICU)进一步治疗。入科后立即留取血液、痰液、颅内穿刺引流液进行培养,予广谱抗生素亚胺培南-西司他丁(0.5g,q6h)和万古霉素(1.0g,q12h)经验性抗感染治疗。入ICU后第4天,患者反复发热,再次留取血培养,3天后结果回报示vanM基因阳性VRE,根据药敏结果,停用万古霉素,改为利奈唑胺。尽管临床症状逐渐好转,入ICU后第10天患者出现腹泻,粪便培养示vanM基因阳性VRE,加用蒙脱石散止泻治疗。入ICU第13天我院院感科对该患者周围环境采样培养,结果示周围环境存在大量vanM基因阳性VRE,而从周围患者的环境中未发现耐药菌株。留取43株环境和2株临床来源VRE进行分子生物学研究。PFGE显示,45株携带vanM基因的屎肠球菌分为4个不同的克隆,MLST显示两种序列分型(sequence type),ST564和ST78。患者周围环境的vanM基因阳性VRE在进行环境消毒后被清除。通过严格执行感染控制措施,有效的阻止了 vanM基因阳性VRE感染的爆发。入ICU后12天该患者转至脑外科病房,3天后患者至当地医院康复锻炼。结论:本研究提示携带vanM基因的VRE易于在肠道和患者周围环境定植,但是通过及时治疗和采取有效的感染控制措施,血流感染患者能得到良好的预后,通过严格实施感控措施,可以有效预防爆发流行。
[Abstract]:Objective: to investigate the clinical manifestations and molecular biological characteristics of a new type of vanM gene positive Enterococcus faecium (VREE) infected by vancomycin-resistant Enterococcus faecium and 45 strains of vanM gene positive Enterococcus faecium in clinical and surrounding environment. It is helpful to further understand the characteristics of this new type of vancomycin resistant Enterococcus infection and related preventive and therapeutic measures. Methods: collect and analyze the clinical data of the patients, according to the hospital disinfection hygiene standards issued in 2012 in China, Sampling the surrounding environment, The specimens were tested as follows: the isolated strains were determined to be Enterococcus faecium by the method of E-test. The minimum inhibitory concentration of 8 antibiotics against Enterococcus faecium was determined by using the method of the minimum inhibitory concentration (MEC). Pulse field gel electrophoresis (PFGE) and multilocus sequence analysis (MLST) were used to determine the results. Homology among strains. Multiplex polymerase chain reaction (PCR) detection of vancomycin-resistant and virulence genes of Enterococcus faecium. Plasmid conjugation test to verify whether the vanM gene can be transferred. Clinical and environmental bacteria were analyzed and compared based on the results. Molecular biological characteristics of the strain. At the same time, In order to prevent further transmission of the genotypic resistant strain, The infected patient was subjected to contact isolation and strict disinfection of the patient's surroundings. Results: a 51-year-old male patient was admitted to hospital with repeated headache and limb dyskinesia. Cranial magnetic resonance imaging (MRI) showed brain abscess. After stereotactic puncture and drainage, they were transferred to our central care unit (ICU) for further treatment. Sputum, intracranial puncture and drainage fluid were cultured and treated with broad-spectrum antibiotic imipenan-cilastatin 0.5 g / q6h and vancomycin 1.0 g / q12h). After 3 days of blood culture, the results showed that vanM gene was positive. According to the results of drug sensitivity, vancomycin was stopped and changed to linazolamide. Although the clinical symptoms gradually improved, the patient developed diarrhea on the 10th day after entering ICU. Fecal culture showed vanM gene positive and was treated with montmorillonite powder to relieve diarrhea. On the 13th day of ICU, the surrounding environment of the patient was sampled and cultured. The results showed that there were a large number of VRE-positive vanM genes in the surrounding environment, but no drug-resistant strains were found in the surrounding patients' environment. The molecular biology of 43 strains of VRE and 2 strains of VRE from clinical sources were collected for molecular biological study. PFGE showed that 45 strains of feces carrying vanM gene were isolated from the surrounding patients. Enterococci were divided into four different clones. MLSTs showed two sequence typing sequences: ST564 and ST78.The vanM gene positive VRE in the patients' surrounding environment was cleared after disinfection, and the infection control measures were strictly carried out. It effectively prevented the outbreak of vanM gene positive VRE infection. 12 days after entering ICU, the patient was transferred to the brain surgery ward for 3 days. Conclusion: this study suggests that VRE carrying vanM gene is easy to be found in the intestine and in the local hospital. The surrounding environment of the patient was colonized. But through timely treatment and effective infection control measures, blood flow infection patients can get a good prognosis, through strict implementation of sensible control measures, can effectively prevent the outbreak of epidemic.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R515
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本文编号：1569987