尿路致病性大肠埃希菌耐药情况与定植相关性研究

发布时间：2018-04-24 05:07

  本文选题：尿路致病性大肠埃希菌 + I型菌毛　； 参考：《天津医科大学》2017年硕士论文

【摘要】：目的尿路致病性大肠埃希菌(UPEC)是引起尿路感染的主要致病菌。黏附素被认为是UPEC最重要的毒力因子,主要包括I型菌毛、P型菌毛、S型菌毛、FIC菌毛和Afa/Dr菌毛等。I型菌毛最常见,而fimH基因编码的I型菌毛顶端fimH蛋白粘附于人尿道上皮细胞,是引发尿路感染的关键环节;P型菌毛同样广泛存在,被认为是UPEC在感染尿道后继续上行至肾脏引起肾盂肾炎的关键因子。本文旨在研究不同耐药程度的UPEC临床分离株I型菌毛及P型菌毛相关菌毛基因fimA、fim B、fimH、papA、papB、papC、papGII在基因水平、转录水平及粘附水平存在的差异,分析其原因,并初步探讨耐药情况与黏附功能的关系,从而提高粘附阻断性治疗的精确度。方法收集2012年3月至2015年10月天津地区四家三级甲等医院(天津医科大学第二医院、天津市一中心医院、天津市儿童医院、天津医科大学总医院)非植入导尿管患者尿液样本分离的非重复感染大肠埃希菌。菌株采用法国生物梅里埃公司VitekⅡ系统鉴定,配套革兰阴性杆菌药敏卡片进行体外药敏试验,筛选出多重耐药菌株和非多重耐药菌株。将UPEC分为敏感组(非多重耐药菌株)和耐药组(多重耐药菌株),每组菌株50株,共100株。通过PCR方法进行基因片段扩增,然后通过琼脂糖凝胶电泳的方式判断毒力因子基因的检出情况;针对不同耐药程度单个毒力因子基因检出阳性的菌株进行荧光定量PCR检测毒力因子基因的相对表达量;UPEC表达I型菌毛的能力通过与酵母细胞的黏附实验来检测,表达P型菌毛的能力通过与人A型红细胞的凝血实验来检测,通过酵母细胞及红细胞凝集试验分别检测I型菌毛及P菌毛的粘附情况。两组之间的比较采用卡方检验和t检验。结果UPEC I型菌毛和P型菌毛通过基因片段扩增,毒力基因fimH、fimA、fimB、papGII、papA、papB、papC在敏感组中的检出率分别为90%、48%、76%、16%、26%、64%、32%,在耐药组中的检出率为84%、46%、58%、42%、36%、56%、38%。fimH基因在敏感组和耐药组的检出率都处于高水平。papGII基因在敏感组中的检出率明显高于耐药组(χ~2=8.208,P0.05),而其他基因在两组间的检出率差异无统计学意义(P0.05)。Rt-PCR结果表明敏感组毒力因子基因fimH、fimB、papC表达量高于耐药组;粘附实验表明敏感组菌株I型菌毛的黏附能力高于耐药组(χ~2=5.769,P0.05),P型菌毛的黏附能力在两组间没有区别(χ~2=2.439,P0.05)。结论UPEC毒力因子基因fimH无论是在敏感组还是耐药组菌株都存在广泛的流传性;UPEC敏感组菌株I型菌毛的粘附能力高于耐药组,推测与耐药菌的适应性代价有关;UPEC粘附功能除受fimH基因及papGII基因这些关键因素影响外,fim及pap基因簇编码的其他基因的缺失和转录也会对I型菌毛及P型菌毛的黏附功能产生影响。
[Abstract]:Objective Urethropathogenicity Escherichia coli (UPEC) is the main pathogen causing urinary tract infection. Adhesion factor is considered to be the most important virulence factor of UPEC, mainly including type I pili, type S pili and Afa/Dr pili. FimH protein at the tip of type I pili encoded by fimH gene adheres to human urethral epithelial cells. It is the key link of urinary tract infection that P type pili also exists widely, which is considered to be the key factor that UPEC continues to uplink to the kidney to cause pyelonephritis after infection of urethra. The purpose of this study was to study the differences in gene level, transcription level and adhesion level between type I and P type pili genes of UPEC clinical isolates with different degrees of drug resistance, and analyze the reasons for the differences in gene level, transcriptional level and adhesion level. The relationship between drug resistance and adhesion function was discussed in order to improve the accuracy of adhesion blocking therapy. Methods from March 2012 to October 2015, four Grade 3A hospitals (the second Hospital of Tianjin Medical University, the first Central Hospital of Tianjin, the Children's Hospital of Tianjin) were collected. Urine samples from patients with non-implanted catheter were isolated from non-repeated infection Escherichia coli. The strains were identified by Vitek 鈪，

本文编号：1795260