湖南省猪源粪肠球菌毒力基因的检测及部分表型的测定

Detection of the virulence genes of swine-origin Enterococcus faecalis and identification of phenotypes of these strains in Hunan Province

采用PCR方法对湖南省分离的42株粪肠球菌的8种毒力相关的基因即溶血素基因cylA、明胶酶基因gelE、表面蛋白基因esp、胶原蛋白黏附素基因ace、聚集物质基因asa1、心内膜炎有关的抗原基因efaA以及2个假定毒力相关基因EF3314、EF0591进行了检测,并用平板法测定了这些分离株的溶血性和明胶溶解性。结果显示,24株粪肠球菌分离株普遍存在EF3314基因,检出率为100%;其次是efaA基因,检出率为92.9%;其他毒力基因gelE、ace、asa1、cylA、esp、EF0591的检出率为分别为88.1%、59.5%、52.4%、54.8%、38.1%、4.76%。菌株在绵羊血琼脂平板上以α溶血为主,而在家兔血琼脂平板中以β溶血为主,家兔血琼脂平板溶血的检出率(95.2%)高于绵羊血琼脂平板溶血的检出率(88.1%)。HN45菌株属于cylA基因阳性菌株却表现为不溶血,而19株cylA基因阴性菌株中只有YZ28菌株在家兔血琼脂平板上表现不溶血,HH57菌株在绵羊血琼脂平板上表现不溶血。5株gelE基因阴性分离株只有2株不分解明胶,37株gelE基因阳性分离株中,有32株分解明胶,5株gelE基因阳性菌株不能分解明胶。结果表明,这42株粪肠球菌中每株菌最少携带1个毒力因子基因,有些菌株最多携带7个毒力因子基因;菌株的溶血与明胶溶解的基因型和表现型并非完全一致。

Eight virulence associated genes were detected from 42 strains of Enterococcus faecalis by PCR in Hunan Province,and the hemolytic and gelatin solubility of these isolates were also determined by plate method. The 8 genes included cytolysin activator gene cylA, gelatinase gene gelE,Enterococcus sur- face protein gene esp, collagen adhesion gene ace, aggregation substance gene asal,E, faecalis endocarditis antigen gene efaA,and 2 supposed virulence associated genes EF3314 and EF0591 were also included. In result,EF3314 gene was widespread in 24 E. faecalis isolates,with the detection rate of 100% ,followed by efaA gene with the detection rate of 92.9~. Detection rates of other virulence genes such as gelE,ace, asal,cylA,esp and EF0591 were 88.1%,59.5%,52.4%,54.8%,38.1~ and 4.76%,respectively. On the strains mainly presented a hemolysis in sheep blood agar plates, while they mainly presented ~ hemolysis in rabbit blood agar plates. Detection rate of rabbit blood agar plate hemolysis was 95.2%, higher than that of sheep blood agar plate hemolysis（88.1%）. HN45 strain was cylA gene-positive, however,it did not present hemolysis. Among the 19 cylA gene-neganve bu,~ J rabbit blood agar plate,and HH57 strain showed no hemolysis in sheep blood agar plates. Among 5 gelE genenegative strains, only 2 strains did not decompose gelatin. Among 37 gelE gene-positive strains, 32 strains could decompose gelatin, and the rest did not decompose gelatin. The results showed that among the 42 strains of E. faecalis, each carried at least one virulence factor gene, and some strains carried 7 virulence factor genes at most. In addition, performance and genotype of strains with regards to hemolysis and gelatin decomposition were not completely consistent.