Virulence, phenotype and genotype characteristics of endodontic Enterococcus spp.
Virulence, phenotype and genotype characteristics of endodontic Enterococcus spp.
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DOI：
10.1111/j.1399-302x.2004.00180.x
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发表时间：
2005-02-01
影响因子：
--
通讯作者：
Dahlén, G
中科院分区：
文献类型：
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作者：
Sedgley, CM;Molander, A;Dahlén, G
背景/目的：肠球菌与持续性根管感染有关，但它们在感染过程中的作用尚不清楚。本研究调查了33株牙髓肠球菌的毒力、表型和基因型别。方法：进行表型试验，包括对抗生素的耐药性、对信息素的聚集反应以及明胶酶、溶血素和细菌素的产生。基因分型包括聚合酶链式反应扩增编码聚集物质AsA和Asa373、细胞溶素激活剂Cyla、明胶酶明胶、明胶酶阴性表型ef1841/FSRC、黏附因子esp和ace以及心内膜炎抗原eFAA的毒力决定簇。结果：表达的潜在毒力特征包括粪肠球菌产生明胶酶(n=23)和对粪肠球菌培养滤液中信息素的反应(n=16)。有14株细菌产生细菌素。5株对四环素耐药，1株对庆大霉素耐药，对氨苄西林、青霉素、氯霉素、红霉素、夫西地酸、卡那霉素、利福平、链霉素和万古霉素敏感。所有分离株均检测到编码eFAA、ACE和ASA的聚合酶链式反应产物，其中20株检测到ESP，6株检测到CylA，但从未检测到Asa373。31株粪肠球菌均检测到明胶酶基因(GLE)，2株粪肠球菌未检测到明胶酶基因，在8株不产明胶酶的粪肠球菌中有6株检测到23.9kb的缺失序列。脉冲场凝胶电泳法和质粒法均显示出明显的克隆类型的遗传多态性。在25株牙髓肠球菌中检测到4个以上的质粒DNA，其中16株有类似的5.1kb的质粒。结论：在牙髓肠球菌中发现了潜在毒力因子的表型和基因证据，特别是明胶酶的产生和对信息素的反应。
Background/aims: Enterococci have been implicated in persistent root canal infections but their role in the infection process remains unclear. This study investigated the virulence, phenotype and genotype of 33 endodontic enterococcal isolates.Methods: Phenotypic tests were conducted for antibiotic resistance, clumping response to pheromone, and production of gelatinase, hemolysin and bacteriocin. Genotype analysis involved polymerase chain reaction amplification of virulence determinants encoding aggregation substances asa and asa373, cytolysin activator cylA, gelatinase gelE, gelatinase-negative phenotype ef1841/fsrC, adherence factors esp and ace, and endocarditis antigen efaA. Physical DNA characterization involved pulsed-field gel electrophoresis of genomic DNA, and plasmid analysis.Results: Potential virulence traits expressed included production of gelatinase by Enterococcus faecalis (n = 23), and response to pheromones in E. faecalis culture filtrate (n = 16). Fourteen strains produced bacteriocin. Five strains were resistant to tetracycline and one to gentamicin, whereas all were susceptible to ampicillin, benzylpenicillin, chloramphenicol, erythromycin, fusidic acid, kanamycin, rifampin, streptomycin and vancomycin. Polymerase chain reaction products encoding efaA, ace, and asa were detected in all isolates; esp was detected in 20 isolates, cylA in six isolates, but asa373 was never detected. The gelatinase gene (gelE) was detected in all isolates of E. faecalis (n = 31) but not in Enterococcus faecium (n = 2); a 23.9 kb deletion sequence corresponding to the gelatinase-negative phenotype was detected in six of the eight E. faecalis isolates that did not produce gelatinase. Pulsed-field gel electrophoresis and plasmid analyses revealed genetic polymorphism with clonal types evident. Plasmid DNA was detected in 25 strains, with up to four plasmids per strain and a similar (5.1 kb) plasmid occurring in 16 isolates.Conclusions: Phenotypic and genotypic evidence of potential virulence factors were identified in endodontic Enterococcus spp., specifically production of gelatinase and response to pheromones.