Man N K, Degremont A, Darbord J C, Collet M, Vaillant P
Department of Nephrology, INSERM U 90, Necker Hospital, Paris, France.
Artif Organs. 1998 Jul;22(7):596-600. doi: 10.1046/j.1525-1594.1998.06195.x.
Biofilms consist of microorganisms immobilized at a substratum surface embedded in an organic polymer matrix of bacterial origin. Tubing drawn from the fluid pathways within dialysis machines of various models were investigated for biofilm. Scanning electron microscopy (SEM), performed on approximately 2 cm2 samples of the tubing inner surfaces revealed that the inner surfaces of the tubing were covered with biofilms consisting of numerous deposits and glycocalix at different stages of formation with components containing bacteria and algae. Evaluations of biomass were performed from tubing sections of various lengths and inner diameters put in tubes containing water for injection and immersed in an ultrasound washtub for 1 h to ensure sloughing of the biofilm. Living bacteria were identified by plating on nutrient agar media and incubation for 48 h at 37 degrees C. Epifluorescent stains were used for the total bacteria count. Lipopolysaccharide levels were determined by the endotoxin activity measurements. Polyoside contents were determined by the colometric method, and the chemical oxygen demand was measured to evaluate the amount of organic substance. Biofilms detached from tubing samples drawn from the water path, bicarbonate path, and fresh dialysate path within dialysis machines contained approximately 1.10(3)-1.10(6) total bacteria/cm2, yet only some living bacteria were found. Endotoxin levels ranged from 1 to 12 EU/cm2. In contrast in the dialysate fluid, no bacteria were found, and the endotoxin content was under the detection level of the method. The polyoside content and chemical oxygen demand of the biomass ranged from 11 to 83 microg/cm2 and from 53 to 234 mg/cm2, respectively. It is concluded that a germ- and endotoxin-free dialysate does not exclude the risks and hazards of bacteria and endotoxin discharge from biofilm developed on the fluid pathway tubing, acting as a reservoir for continuous contamination, and efforts in the optimization of cleaning and disinfection procedures used for hemodialysis systems should aim to detach and neutralize biofilm when necessary.
生物膜由固定在基质表面的微生物组成，这些微生物嵌入细菌来源的有机聚合物基质中。对从各种型号透析机的流体通路中抽取的管材进行了生物膜研究。对管材内表面约2平方厘米的样本进行扫描电子显微镜（SEM）检查发现，管材内表面覆盖着生物膜，这些生物膜由处于不同形成阶段的大量沉积物和糖萼组成，其成分包含细菌和藻类。从不同长度和内径的管材段中截取样本，放入装有注射用水的试管中，并在超声清洗槽中浸泡1小时，以确保生物膜脱落，然后对生物量进行评估。通过在营养琼脂培养基上接种并在37℃下培养48小时来鉴定活细菌。使用落射荧光染色法对细菌总数进行计数。通过内毒素活性测量来确定脂多糖水平。采用比色法测定多糖含量，并测量化学需氧量以评估有机物的量。从透析机内水路、碳酸氢盐通路和新鲜透析液通路抽取的管材样本上分离出的生物膜，每平方厘米含有约1.10(3)-1.10(6)个细菌，但仅发现了一些活细菌。内毒素水平在1至12 EU/平方厘米之间。相比之下，在透析液中未发现细菌，内毒素含量低于该方法的检测水平。生物膜的多糖含量和化学需氧量分别在11至83微克/平方厘米和53至234毫克/平方厘米之间。得出的结论是，无细菌和内毒素的透析液并不能排除在流体通路管材上形成的生物膜释放细菌和内毒素的风险和危害，生物膜可作为持续污染的储存库；优化用于血液透析系统的清洁和消毒程序的工作应旨在必要时分离和中和生物膜。
