乳糖多管发酵法与酶底物法检测水中大肠埃希菌结果比较

Comparison of results of lactose multiple tube fermentation method and enzyme substrate method in detection of Escherichia coli

目的为检测饮用水中大肠埃希菌选用一种准确、快速、简便的检测方法。方法按生活饮用水标准检验方法(GB/T5750-2006)中乳糖多管发酵法和酶底物法测定水中大肠埃希菌,比较两法的适用性、灵敏度、检测结果的差异。结果乳糖多管发酵法和酶底物法均能检出大肠埃希菌,二法适用性无差异;乳糖多管发酵法灵敏度为10cfu/100m L,底物酶法灵敏度为1cfu/100m L,对40份水样进行检测,乳糖多管发酵法检测周期为72h,检出大肠埃希菌33份,检出率为82.5%(33/40);酶底物法检测周期为24h,检出大肠埃希菌36份,检出率为90.0%(36/40);二法检出率差异无统计学意义(χ2=0.9486,P=0.3301)。二法均检出大肠埃希菌33份,检出符合率为91.67%(33/36),二法均未检出大肠埃希菌5份,未检出符合率为100%(4/4),二法检测效果差异无统计学意义(配对χ2=1.3333,P=0.2482);二法检测结果,差异无统计学意义(配对t=0.5295,P=0.5994)。结论乳糖多管发酵法和酶底物法均可检测饮用水中大肠埃希菌,酶底物法灵敏度高于乳糖多管发酵法,检测时间比乳糖多管发酵法缩短48h。采用酶底物法检测水中大肠埃希菌,能更快捷、准确的报告检测结果。

Objective To select an accurate、fast and convenient method for detection of Escherichia coli in drinkingwater. Methods Escherichia coli in drinking water was detected using lactose multiple tube fermentation method andenzyme substrate method introduced in the standard methods for inspection of drinking water（GB5750- 2006）, theapplicability, sensitivity and the difference of the two methods were compared. Results Escherichia coli could be detectedboth by the lactose multiple tube fermentation method and the enzyme substrate method and without differences in terms ofapplicability. The sensitivity of lactose multiple tube fermentation method and substrate enzyme method were 10cfu/100 m L and1cfu/100 m L. In detection of 40 water samples the positive rate of lactose multiple tube fermentation method 82.5%（30/40） for aduration of seventy-two hours, while the positive rate of enzyme substrate method was 90.0%（36/40）for a duration of twentyfour hours, without significant difference（χ^2=0.9486,P=0.3301）. Escherichia coli was detected in thirty-three water sampleswith both methods with the coincidence rate of 91.67%（33/36）. No Escherichia coli was detected in five samples with bothmethods with the negative coincidence rate of 100%（4/4）, therefore, there is no significant difference in the effect and results ofdetection of Escherichia coli between two methods（χ^2=1.3333,P=0.2482）and（t =0.5295,P=0.5994）.Conclusion Lactosemultiple tube fermentation method and the enzyme substrate method can both used for detection of Escherichia coli in thedrinking water, but the sensitivity of enzyme substrate method is higher than the lactose multiple tube fermentation method asthe duration of detection time of the latter 48 hours less than the former, thus it allows rapid detection and accurate reporting ofthe results.