Åström Johan, Pettersson Thomas J R, Reischer Georg H, Norberg Tommy, Hermansson Malte
Tyréns AB, Lilla Badhusgatan 2, SE-411 21 Gothenburg, Sweden.
Environ Sci Technol. 2015 Feb 3;49(3):1311-8. doi: 10.1021/es504579j. Epub 2015 Jan 20.
Several assays for the detection of host-specific genetic markers of the order Bacteroidales have been developed and used for microbial source tracking (MST) in environmental waters. It is recognized that the source-sensitivity and source-specificity are unknown and variable when introducing these assays in new geographic regions, which reduces their reliability and use. A Bayesian approach was developed to incorporate expert judgments with regional assay sensitivity and specificity assessments in a utility evaluation of a human and a ruminant-specific qPCR assay for MST in a drinking water source. Water samples from Lake Rådasjön were analyzed for E. coli, intestinal enterococci and somatic coliphages through cultivation and for human (BacH) and ruminant-specific (BacR) markers through qPCR assays. Expert judgments were collected regarding the probability of human and ruminant fecal contamination based on fecal indicator organism data and subjective information. Using Bayes formula, the conditional probability of a true human or ruminant fecal contamination given the presence of BacH or BacR was determined stochastically from expert judgments and regional qPCR assay performance, using Beta distributions to represent uncertainties. A web-based computational tool was developed for the procedure, which provides a measure of confidence to findings of host-specific markers and demonstrates the information value from these assays.
已经开发了几种用于检测拟杆菌目宿主特异性遗传标记的检测方法，并将其用于环境水体中的微生物源追踪（MST）。人们认识到，在新的地理区域引入这些检测方法时，其源敏感性和源特异性是未知且可变的，这降低了它们的可靠性和实用性。开发了一种贝叶斯方法，在对饮用水源中用于MST的人类和反刍动物特异性qPCR检测方法的效用评估中，将专家判断与区域检测方法的敏感性和特异性评估相结合。通过培养分析了来自拉达斯约恩湖的水样中的大肠杆菌、肠道肠球菌和体细胞噬菌体，并通过qPCR检测方法分析了人类（BacH）和反刍动物特异性（BacR）标记。基于粪便指示生物数据和主观信息，收集了有关人类和反刍动物粪便污染概率的专家判断。使用贝叶斯公式，根据专家判断和区域qPCR检测方法的性能，使用贝塔分布来表示不确定性，随机确定了在存在BacH或BacR的情况下真正的人类或反刍动物粪便污染的条件概率。为此程序开发了一个基于网络的计算工具，该工具提供了对宿主特异性标记物发现的置信度衡量，并展示了这些检测方法的信息价值。
