Harrison Joe J, Turner Raymond J, Ceri Howard
Department of Biological Sciences, University of Calgary, Calgary, AB, Canada; and Biofilm Research Group, University of Calgary, Calgary, AB, Canada.
FEMS Microbiol Lett. 2007 Jul;272(2):172-81. doi: 10.1111/j.1574-6968.2007.00745.x. Epub 2007 May 8.
Many Candida spp. produce surface-adherent biofilm populations that are resistant to antifungal compounds and other environmental stresses. Recently, certain chelating agents have been recognized as having strong antimicrobial activity against biofilms of Candida species. This study investigated and characterized the concentration- and time-dependent killing of Candida biofilms by the chelators tetrasodium EDTA and sodium diethyldithiocarbamate. Here, Candida albicans and Candida tropicalis biofilms were cultivated in the Calgary Biofilm Device and then exposed to gradient arrays of these agents. Population survival was evaluated by viable cell counting and by confocal laser scanning microscopy (CLSM) in conjunction with fluorescent viability staining. At concentrations of > or =2 mM, both EDTA and diethyldithiocarbamate killed c. 90-99.5% of the biofilm cell populations. Notably, a small fraction (c. 0.5-10%) of biofilm cells were able to withstand the highest concentrations of these antifungals that were tested (16 and 32 mM for EDTA and diethyldithiocarbamate, respectively). Interestingly, CLSM revealed that these surviving cells were irregularly distributed throughout the biofilm community. These data suggest that the use of chelating agents against biofilms of Candida spp. may be limited by the refractory nature of a variant cell subpopulation in the surface-adherent community.
许多念珠菌属物种会产生表面附着的生物膜群体，这些群体对抗真菌化合物和其他环境压力具有抗性。最近，某些螯合剂已被认为对念珠菌属生物膜具有强大的抗菌活性。本研究调查并表征了螯合剂乙二胺四乙酸四钠和二乙基二硫代氨基甲酸钠对念珠菌生物膜的浓度和时间依赖性杀灭作用。在此，白色念珠菌和热带念珠菌生物膜在卡尔加里生物膜装置中培养，然后暴露于这些试剂的梯度阵列中。通过活细胞计数以及结合荧光活力染色的共聚焦激光扫描显微镜（CLSM）评估群体存活率。在浓度≥2 mM时，EDTA和二乙基二硫代氨基甲酸钠均杀死了约90 - 99.5%的生物膜细胞群体。值得注意的是，一小部分（约0.5 - 10%）生物膜细胞能够耐受所测试的这些抗真菌剂的最高浓度（EDTA和二乙基二硫代氨基甲酸钠分别为16 mM和32 mM）。有趣的是，CLSM显示这些存活细胞在整个生物膜群落中分布不规则。这些数据表明，使用螯合剂对抗念珠菌属生物膜可能会受到表面附着群落中变异细胞亚群的难治性性质的限制。
