Edberg S C, Allen M J, Smith D B
Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
Appl Environ Microbiol. 1988 Jun;54(6):1595-601. doi: 10.1128/aem.54.6.1595-1601.1988.
A defined substrate method was developed to simultaneously enumerate total coliforms and Escherichia coli from drinking waters without the need for confirmatory or completed tests. It is a new method based on technology that uses a hydrolyzable substrate as a specific indicator-nutrient for the target microbes. No equipment other than a 35 degrees C incubator and long-wavelength (366-nm) light is necessary. To perform the test, one only has to add water to the powdered ingredients in a tube or flask. If total coliforms are present in the water sample, the solution will change from its normal colorless state (no target microbes present) to yellow. The specific presence of E. coli will cause the same tube to fluoresce under a longwave (366-nm) UV lamp. The test, called Autoanalysis Colilert (AC), was compared with Standard Methods for the Examination of Water and Wastewater 10-tube multiple tube fermentation (MTF) in a national evaluation. Five utilities, representing six U.S. Environmental Protection Agency regions, participated. All water samples came from distribution systems. Split samples from a wide variety of water sources were analyzed for the MPN-versus-MPN comparison. A total of 1,086 tubes were positive by MTF, and 1,279 were positive by AC. There was no statistical difference between MTF and AC. Species identifications from positive tubes confirmed the sensitivity of the AC. A national evaluation of the AC test showed that it: (i) was as sensitive as Standard Methods MTF, (ii) specifically enumerated 1 total coliform per 100 ml, in a maximum of 24 h, (iii) simultaneously enumerated 1 E. coli per 100 ml in the same analysis, (iv) was not subject to false-positive or false-negative results by heterotrophic bacteria, (v) did not require confirmatory tests, (vi) grew injured coliforms, (vii) was easy to inoculate, and (viii) was very easy to interpret.
开发了一种特定底物法，可同时对饮用水中的总大肠菌群和大肠杆菌进行计数，无需进行确证试验或完整试验。这是一种基于新技术的方法，该技术使用一种可水解底物作为目标微生物的特定指示性营养物。除了35摄氏度的培养箱和长波长（366纳米）光外，无需其他设备。进行该测试时，只需将水加入试管或烧瓶中的粉末状成分中。如果水样中存在总大肠菌群，溶液将从正常的无色状态（无目标微生物）变为黄色。大肠杆菌的特定存在会使同一试管在长波（366纳米）紫外灯下发出荧光。该测试称为自动分析大肠菌群检测法（AC），在一项全国性评估中与《水和废水检验标准方法》中的10管多管发酵法（MTF）进行了比较。代表美国环境保护局六个地区的五家公用事业公司参与了评估。所有水样均来自配水系统。对来自各种水源的分流样本进行了最大可能数（MPN）对MPN的比较分析。MTF法检测出1086管呈阳性，AC法检测出1279管呈阳性。MTF法和AC法之间无统计学差异。对阳性试管进行的菌种鉴定证实了AC法的灵敏度。对AC测试的全国性评估表明，它：（i）与标准方法MTF一样灵敏，（ii）在最长24小时内可特异性计数每100毫升水中的1个总大肠菌群，（iii）在同一分析中可同时计数每100毫升水中的1个大肠杆菌，（iv）不受异养细菌假阳性或假阴性结果的影响，（v）无需确证试验，（vi）能使受损大肠菌群生长，（vii）易于接种，（viii）非常易于解读。
