Department of Cariology, Endodontology, Pedodontology and Oral Microbiology, Academic Centre for Dentistry Amsterdam, Amsterdam, The Netherlands.
Int Endod J. 2011 Dec;44(12):1110-7. doi: 10.1111/j.1365-2591.2011.01929.x. Epub 2011 Aug 22.
To investigate the effect of hyperosmotic hyperosmosis or alkaline stress on a dual-species biofilm of Enterococcus faecalis and Pseudomonas aeruginosa.
Biofilms were grown on glass cover slips suspended in bacterial inoculate for 96 h, after which the cover slips with attached biofilms were immersed in brain heart infusion broth (BHI-broth) with 6 mol L(-1) sodium chloride (NaCl) representing the hyperosmotic group or Ca(OH)(2), pH 12.1, representing the alkaline group. Two per cent sodium hypochlorite and BHI- broth served as positive and negative controls, respectively. After treatment, the biofilms were washed, harvested and plated on blood-agar plates after serial dilution. The bactericidal effect was assessed by determining the colony-forming units (CFU). The effect on the biofilm mass was imaged with confocal laser scanning microscopy (CLSM).
Hyperosmosis reduced the CFU of both species significantly after 72 h (P < 0.0001). After 168 h, P. aeruginosa was eradicated and the E. faecalis reduction was more than 99%. High pH could not induce a significant bacterial reduction. CLSM revealed dense flocculation of the biofilms incubated in alkaline broth.
Hyperosmosis effectively reduced a dual-species biofilm of E. faecalis and P. aeruginosa, whilst high pH had limited bactericidal effect in this model.
研究高渗性或碱性应激对粪肠球菌和铜绿假单胞菌双物种生物膜的影响。
生物膜在玻璃载玻片上生长，载玻片悬挂在细菌接种物中 96 小时，然后将附有生物膜的载玻片浸入含有 6mol/L 氯化钠（NaCl）的脑心浸液肉汤（BHI-肉汤）中，代表高渗组，或 pH 值为 12.1 的 Ca(OH) 2 ，代表碱性组。2%次氯酸钠和 BHI-肉汤分别作为阳性和阴性对照。处理后，用无菌水冲洗生物膜，经系列稀释后收获并接种于血琼脂平板。通过测定菌落形成单位（CFU）评估杀菌效果。使用共聚焦激光扫描显微镜（CLSM）对生物膜质量的影响进行成像。
高渗作用在 72 小时后显著降低了两种细菌的 CFU（P < 0.0001）。168 小时后，铜绿假单胞菌被根除，粪肠球菌的减少超过 99%。高 pH 值不能诱导明显的细菌减少。CLSM 显示在碱性肉汤中孵育的生物膜发生了密集的絮凝。
高渗作用可有效减少粪肠球菌和铜绿假单胞菌的双物种生物膜，而在该模型中，高 pH 值对杀菌作用有限。
