Institute of Microbiology Prof Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Res Microbiol. 2011 Feb-Mar;162(2):151-8. doi: 10.1016/j.resmic.2010.09.018. Epub 2010 Nov 24.
The high prevalence of Enterococcus faecalis in root canal treated teeth with post-treatment disease, as evidenced by both molecular and traditional culturing methods, suggests that this species may be a key player in endodontic treatment failure. This study aimed to detect virulence factors by phenotypic and western blotting tests, and virulence genes by PCR from 20 clinical strains of E. faecalis isolated from treated root canals of teeth with (10) or without (10) apical periodontitis. Moreover, genomic diversity of these strains was assessed by pulsed-field gel electrophoresis (PFGE) and rep-PCR. All 20 strains presented the gelE gene (gelatinase), but 10 of them did not hydrolyze gelatin. Seven of the 10 gelatinase-producing isolates were recovered from root canals with lesions, which suggests a role for this virulence factor in the pathogenesis of post-treatment disease. The esp gene was expressed only in cases where gelatinase production was negative. The other virulence genes were found in 90% (efaA and ace genes), 45% (agg gene) and 95% (cpd gene) of the E. faecalis isolates. As for PFGE and rep-PCR, no specific clonal type of E. faecalis was found in association with teeth with or without disease, revealing the interindividual clonal diversity of endodontic infections.
经分子和传统培养方法证实，治疗后发生病变的根管治疗牙中粪肠球菌的高患病率表明，该物种可能是根管治疗失败的关键因素。本研究旨在通过表型和 Western blot 试验检测毒力因子，并通过 PCR 从 20 株从有（10 株）或无（10 株）根尖周炎的治疗后根管中分离出的粪肠球菌临床株中检测毒力基因。此外，还通过脉冲场凝胶电泳（PFGE）和重复序列 PCR 评估这些菌株的基因组多样性。所有 20 株菌均携带 gelE 基因（明胶酶），但其中 10 株菌不水解明胶。10 株产明胶酶的分离株中有 7 株来自有病变的根管，表明该毒力因子在治疗后疾病的发病机制中起作用。esp 基因仅在明胶酶产生阴性时表达。其他毒力基因在 90%（efaA 和 ace 基因）、45%（agg 基因）和 95%（cpd 基因）的粪肠球菌分离株中被发现。至于 PFGE 和 rep-PCR，在有无疾病的牙齿中均未发现粪肠球菌的特定克隆型，这表明根管感染存在个体间的克隆多样性。
