眼源性蜡样芽孢杆菌vrrA基因型及其与病情和预后关系

摘要

目的 建立PCR检测眼源性蜡样芽孢杆菌,了解不同vrrA基因型蜡样芽孢杆菌感染与临床病情和预后关系.方法 选择vrrA为靶基因设计引物,建立检测蜡样芽胞杆菌PCR.PCR产物用琼脂糖凝胶电泳检测并进行序列测定.采用Clustal 软件对获得的vrrA基因序列进行分型.对不同vrrA基因型蜡样芽胞杆菌感染与眼内炎患者病情严重程度及转归分析与比较.结果 所建立的PCR可有效检测眼源性蜡样芽胞杆菌并有较高的敏感性和特异性.5株分离自眼内炎患者标本中的蜡样芽胞杆菌可分为MT1、MT2、MT3三种vrrA基因型,其中MT1、MT2型各2株,MT3型1株.MT1和MT2型蜡样芽胞杆菌感染性眼内炎病情重、预后差,MT3型蜡样芽胞杆菌感染性眼内炎病情较轻、预后较好.结论 vrrA基因为靶基因的PCR可用于眼源性蜡样芽孢杆菌快速检测.不同蜡样芽孢杆菌vrrA基因型感染所致的眼内炎病情严重程度及转归有明显差异.%In order to establish a PCR assay for detecting Bacillus cereus from eye-origin, and to understand the correlation among vrrA genotypes and disease severity and prognosis,the vrrA gene was selected as the target gene to design primers for establishirg a PCR to detect Bacillus cereus.The PCR product was examined by agarose gel electronphoresis and analyzed by sequencing.Clustal software was applied for genotyping of the obtained vrrA gene sequences.Correlation among the infec tion of different vrrA genotypes and severity as well as prognosis of endophthalmitis were analyzed and compared.The established PCR could efficiently detect Bacillus cereus from eye-origin with high sensitivity and specificity.The Bacillus cereus isolated from the specimens of endophthalmitis patients were classified as MT1, MT2 and MT3 vrrA genotypes.Among the five Bacillus cereus isolates, two were MT1 genotype, two were MT2 genotype and one was MT3 genotype.The endophthalmitis caused by infection of either MT1 or MT2 genotype of Bacillus cereus presented more seriously pathogenetic condition and unfavourable prognosis.On the contrast, the endophthalmitis caused by infection of MT3 genotype of Bacillus cereus presented more mildly pathogenetic condition and better prognosis.Our study shows the PCR using vrrA as the target gene could be used to rapidly detect Bacillus cereus from eye-origin.There are diversities among the infection of different vrrA gene genotypes of Bacillus cereus and severity as well as prognosis of Bacillus cereus endophthalmitis.