屎肠球菌临床分离株生物膜形成与毒力基因及ST分型之间的关系

The relationship between biofilm formation of Enterococcus faecium clinical isolates and its virulence genes and STs

目的研究临床分离屎肠球菌株生物膜形成与ST分型和毒力基因之间的关系。方法收集深圳市南山医院2011—2017年临床分离的不重复屎肠球菌共122株,采用结晶紫染色法检测细菌生物膜形成能力,对分离株进行多位点序列分型(MLST)分析,PCR方法检测屎肠球菌临床株毒力基因表面蛋白(esp)、透明质酸酶(hyl)、表面聚集蛋白(asa1)、明胶酶(gelE)、溶细胞素(cylA)等的分布。结果122株屎肠球菌生物膜形成阳性率为49.2%,其生物膜形成能力主要表现为弱阳性。屎肠球菌毒力基因检测提示esp和hyl检出率分别为39.3%(48/122)和15.6%(19/122),所有菌株未检测到asa1、gelE、cylA;其中esp阳性与生物膜形成能力相关(P<0.05),而hyl阳性与生物膜形成能力无相关性(P>0.05)。MLST分型提示屎肠球菌临床株主要为ST78及ST18型,分别为26株及18株,其中ST78与ST18之间生物膜形成能力差异无统计学意义(P>0.05),esp更常见于ST78分离株。结论临床分离屎肠球菌生物膜形成能力较弱,其毒力基因esp阳性更容易形成生物膜,而hyl与生物膜形成能力无明显相关性,ST78与ST18之间生物膜形成能力无明显差异,esp更常见于ST78分离株。

Objective To study the characteristics of clinical isolates of Enterococcus faecium biofilm formation and its relationship with sequence types(STs)and virulence genes.Methods A total of 122 Enterococcus faecium isolates were obtained from Nanshan Hospital of the Affiliated Hospital of Guangdong Medical University between 2011 and 2017.The biofilm formation ability of the bacteria was detected by crystal violet staining,and the isolates were subjected to multi-locus sequence typing(MLST)analysis.PCR was used to detect the virulence gene of surface protein(esp),hyaluronidase(hyl),surface aggregation protein(asa1),gelatinase(gelE)and cytolysin(cylA).Results The positive rate of biofilm formation of122 Enterococcus faecium was 49.2%,and the biofilm formation ability was mainly weakly positive.The virulence gene test of Enterococcus faecium showed that the detection rates of esp and hyl were 39.3%(48/122)and 15.6%(19/122),while all strains did not detect asa1,gelE,cylA.There was correlation between the positive rate of esp and the ability of biofilm(P<0.05),and no significant correlation between the positive rate of hyl and the ability of biofilm formation(P>0.05).The MLSTs indicated that the Enterococcus faecium were mainly ST78 and ST18,and the two STs were 26 and 18,respectively.There was no significant difference in biofilm formation ability between ST78 and ST18,and esp is more common in ST78 isolates.Conclusion Enterococcus faecium has weak bio-forming ability,and the virulence gene hyl are not correlated with biofilm formation ability.There is no difference in biofilm formation ability between ST78 and ST18.