粪肠球菌和屎肠球菌临床分离株的毒力因子与耐药性分析

Comparison of the Incidence of Virulence Determinants and Antibiotic Resistance between Clinical Enterococcus faecalis and Enterococcus faecium Strains

目的检测临床分离肠球菌的耐药和毒力因子,比较粪肠球菌和屎肠球菌的耐药性和毒力特征。方法采用琼脂稀释法检测肠球菌对万古霉素(VAN)、四环素(TET)、环丙沙星(CIP)、红霉素(ERY)、复方新诺明(SMZ)、替考拉宁(TEC)、克林霉素(CLI)的耐药性;采用微量板测定肠球菌的生物膜形成能力;观察肠球菌的β溶血和明胶溶解结果,同时用PCR方法检测相应基因cylA和gelE。结果粪肠球菌和屎肠球菌的耐药率分别为0%～100%和3.23%～96.77%,后者对环丙氟哌酸、红霉素的耐药程度高于前者。β溶血试验阳性率为19.23%,cylA基因阳性率为35.38%;明胶表型阳性率为21.54%,gelE阳性率为40.0%,其中有46.15%(12/26)阳性者未出现相应表型;生物膜形成检出率为36.92%;粪肠球菌3种毒力因子(表型和基因型)的阳性率均高于屎肠球菌。结论屎肠球菌耐药率高于粪肠球菌,粪肠球菌毒力因子阳性率高于屎肠球菌。

Objective The aim of this investigation was to compare the incidence of virulence determinants and antibiotic resistance between Enterococcus faecalis and E. faecium strains isolated from patients. Methods Antibiotic susceptibility testing was performed using broth microdilution susceptibility tests to determine the Minimum Inhibition Concentration （MIC）. The phenotypic assay of gelatinase activity and β-hemolysis were performed on agar plate supplemented with 3% gelatin and 5% rabbit blood, respectively. Virulence determinants were detected by PCR. The biofilm assay was performed by using microtiter plate. Results The antibiotic resistant percentage of E. faecalis and E. faecium strains were 0%- 100% and 3.23%-96.77%, respectively. The prevalence of the virulence factors of genotype and phenotype were ： β-hemolysin 19.23% vs. 35.38%, gelatinase 21.54% vs. 40.0%, biofilm formation 36.92%, respectively. Phenotypic testing revealed the existence of apparently silent gelE and cylA genes. Conclusion The results of this study indicate that E. faecalis have more virulence determinants and E. faecium have a higher antibiotic resistant percentage.