Do different strains of E. faecalis have the same behavior towards intracanal medications in in vitro research?

Abstract: The aim of this study was to evaluate the antimicrobial action of different endodontic pastes against Enterococcus faecalis ATCC 29212, isolated from the urinary tract, and compare the action with E. faecalis ATCC 4083, isolated from the root canal. For this purpose, dentin blocks were infected for 21 days with both bacteria at different time-intervals to ensure there would be no cross contamination. After this period, blocks were immersed in the test medications for 7 days, according to the following groups: CH/S, CH/P, CH/CMCP, CH/CHX, CH/DAP and TAP. Images of the samples were captured with a confocal microscope and the percentage of live cells was computed by means of the Bioimage program. The ATCC 29212 strain was shown to be more resistant to CH/SS, Calen, CH/DAP, and TAP than the ATCC 4083 strain. The antimicrobial action of the medications against each strain were divergent concerning the order of susceptibility. The authors concluded that the strains behaved in a different manner: in general, those extracted from the urinary tract were more resistant to the tested medications. Therefore, when E. faecalis must be used for in vitro research in endodontics, we suggest the use of ATCC 4083 strain to obtain results that are closer to the clinical reality.

摘要：本研究旨在评估不同牙髓治疗糊剂对分别从尿路分离的粪肠球菌（Enterococcus faecalis）ATCC 29212，以及从根管分离的粪肠球菌ATCC 4083的抗菌活性，并对比二者的抗菌效果。为此，研究人员以不同时间间隔用两种细菌感染牙本质块，感染周期为21天，以确保无交叉污染。此阶段结束后，按照以下分组将牙本质块浸入受试药物中7天：CH/S、CH/P、CH/CMCP、CH/CHX、CH/DAP及TAP。通过共聚焦显微镜采集样本图像，并借助Bioimage软件计算活细胞百分比。实验结果显示，相较于ATCC 4083菌株，ATCC 29212菌株对CH/SS、Calen、CH/DAP及TAP的耐药性更强。受试药物对两种菌株的抗菌活性排序存在差异。研究人员得出结论：两种菌株的抗菌响应特性存在差异——总体而言，从尿路分离的菌株对受试药物的耐药性更高。因此，若需在牙髓病学体外研究中使用粪肠球菌，建议采用ATCC 4083菌株，以获得更贴近临床实际的实验结果。