新型胰蛋白胨葡萄糖培养基用于透析用水细菌检测的临床适用性多中心研究

A multicenter study on the clinical applicability of a novel tryptone glucose extract agar medium for the detection of bacteria in dialysis water

目的明确一种新型胰蛋白胨葡萄糖(tryptone glucose extract agar,TGEA)培养基用于透析用水细菌检测的临床适用性。方法分别在4家血液透析中心的水处理系统出水口、回水口、血液透析机(进水软管连接到透析机的位置)及稀释后的透析液等4个点取样,使用TGEA涂布法(20℃,168h)、TGEA薄膜过滤法(20℃,168h)和营养琼脂培养基(37℃,48h)作为对照培养基,以新型TGEA培养基(20℃,168h)作为验证培养基,进行细菌培养并在培养结束后进行细菌菌落计数。结果 TGEA涂布法、TGEA薄膜法和验证培养基的Log10(菌落计数)3者间无显著性差异,均高于营养琼脂培养基(F=3.346,P=0.025);菌落检出率TGEA涂布法、薄膜法和验证培养基均高于营养琼脂培养基,但多组间比较未见显著性差异(χ~2=4.267,P=0.234);Bland-Altman分析显示验证培养基与TGEA涂布法和薄膜法的一致性好;验证培养基与TGEA涂布法和薄膜法菌落计数比值在0.5~1.5范围内。结论新型胰蛋白胨葡萄糖培养基与经典TGEA涂布法和TGEA薄膜过滤法一致性好,操作简便,全过程可在常规环境下完成,具有良好的临床适用性。

Objective To identify the clinical applicability of a novel tryptone glucose extract agar（TGEA） medium for the detection of bacteria in dialysis water. Methods Water samples were collected from the four hemodialysis centers at the outlet of water treatment system, backwater point of water treatment system, hemodialysis machine（inlet hose connected to the dialysis machine）, and diluted dialysate. Samples were cultured with TGEA medium using spreading method（20 ℃, 168 hours） and TGEA membrane filtration method（20 ℃, 168 hours）, and with nutrient agar medium（37 ℃, 48 hours） as the control medium. TGEA medium（20 ℃, 168 hours） was used as a validation medium, and bacterial colonies were counted at the end of the culture. Results The value of log10（colony counts） had no significant differences between the TGEA spreading method, the TGEA membrane filtration method, and the validation medium method, but was higher than that of nutrient agar medium method（F=3.346, P=0.025）. The detection rate of bacteria was higher from the three TGEA media than from nutrient agar medium, but P value was greater than 0.05 probably due to the limited sample size（χ~2=4.267, P=0.234）. Bland-Altman analysis showed that the result from validation medium was consistent with the results from TGEA spreading method and TGEA membrane filtration method. The colony number ratios of validation medium/TGEA spreading method and validation medium/membrane filtration method were all in the range of 0.5~1.5. Conclusion The novel TGEA medium is well applicable for clinical use. The culture process using the novel TGEA medium is easy to operate in a routine environment.