不同检测方法对透析用水细菌监测的应用性研究

Applied study on different test method for bacterial monitoring in dialysis water

目的探求胰化蛋白胨葡萄糖培养基(tryptone glucose extract agar,TGEA)用于透析用水菌落计数的可行性,为日常监测提供科学依据。方法抽取天津市11个区的20家医疗机构透析用水水样74份,取样部位分别为水处理系统的出水口、回水口和断开的透析机与进水软管的连接处。分别采用倾注法、涂布法及过滤法进行实验,使用TGEA(20℃、168h)和普通营养琼脂(36℃、48h)进行细菌培养,并观察细菌菌落数。结果倾注法、涂布法、过滤法TGEA组的检出率、log_(10)菌落计数结果,无显著性差异(χ~2值分别为0.115,0.843;P值分别为0.944,0.656),均高于对应的营养琼脂组(χ~2值分别为19.140,29.691,P值分别0.002,<0.001),具有显著性差异;Bland-Altman图显示,3法TGEA组与对应营养琼脂组差值均较大、一致性较差;3法TGEA组内差值的均值较小,一致性较好。结论高营养高温培养的检测条件可能屏蔽了的透析用水的真实的微生物水平,TGEA低温长时间培养用于透析用水菌落计数具有很好的临床适应性,试剂盒过滤法具有操作简单、快捷、高效、准确等特点,适合日常监测使用。

Objective To evaluate the feasibility of tryptone glucose extract agar(TGEA)medium for the detection of bacteria number in dialysis water in order to provide a reliable method for routine examination of bacterial contamination in dialysis water.Methods Seventy-four samples of dialysis water were collected from 20 hemodialysis centers at outlet of water treatment system,backwater point of water treatment system,and inlet hose connected to hemodialysis machine.Pour plate method,spreading method and membrane filtration method were used for the incubation of water samples in TGEA medium(20℃,168h)and conventional nutrient agar medium(36℃,48h).After incubation,number of bacterial colonies was quantified.Result The detection rate of bacteria and the value of log10colony counts had no significant differences between TGEA pour plate method,TGEA spreading method and TGEA membrane filtration method(χ^2=0.115 and 0.843 respectively;P=0.944 and 0.656 respectively),but were higher than the results of conventional nutrient agar medium using the three inoculation methods(χ^2=19.140 and 29.691 respectively;P=0.002 and<0.001 respectively).Bland-Altman analysis showed that the results from TGEA medium(20℃,168h)and better consistency.Conclusions The method of conventional nutrient agar medium(36℃,48h)can interfere with the detection of bacteria number in dialysis water,while TGEA medium(20℃,168h)is applicable for clinical use.The reagent kit using membrane filtration method has the characteristics of simple and fast operation with high efficiency and accuracy,suitable for routine surveillance of bacterial contamination in dialysis water.