Comparison of fecal indicators with pathogenic bacteria and rotavirus in rural Bangladesh groundwater@en

Groundwater is routinely analyzed for fecal indicators but direct comparisons of fecal indicators to the presence of bacterial and viral pathogens are rare. This study was conducted in rural Bangladesh where the human population density is high, sanitation is poor, and groundwater pumped from shallow tubewells is often contaminated with fecal bacteria. Five indicator microorganisms (E. coli, total coliform, F+RNA coliphage, Bacteroides and human-associated Bacteroides (HuBacteroides)) and various environmental parameters were compared to the direct detection of waterborne pathogens by quantitative PCR in groundwater pumped from 50 tubewells. Rotavirus was detected in groundwater filtrate from the largest proportion of tubewells (40%), followed by Shigella (10%), Vibrio (10%), and pathogenic E. coli (8%). Spearman rank correlations and sensitivity-specificity calculations indicate that some, but not all, combinations of indicators and environmental parameters can predict the presence of pathogens. Culture-dependent fecal indicator bacteria measured on a single date did not predict bacterial pathogens, but annually averaged monthly measurements of culturable E. coli did improve prediction for total bacterial pathogens. F+RNA coliphage were neither correlated nor sufficiently sensitive towards rotavirus, but were predictive of bacterial pathogens. A qPCR-based E. coli assay was the best indicator for the bacterial pathogens, rotavirus and all pathogens combined. Since groundwater cannot be excluded as a significant source of diarrheal disease in Bangladesh and neighboring countries with similar characteristics, the need to develop more effective methods for screening tubewells with respect to microbial contamination is necessary.尽管常规会对地下水开展粪便指示物检测，但针对粪便指示物与细菌、病毒病原体检出情况的直接对比研究仍较为匮乏。本研究在孟加拉国乡村地区开展，该区域人口密度较高、卫生条件简陋，且浅管井抽取的地下水常受粪便细菌污染。本研究针对50口管井抽取的地下水，选取5种指示微生物——大肠杆菌（E. coli）、总大肠菌群、F+RNA噬菌体（F+RNA coliphage）、拟杆菌属（Bacteroides）以及人源拟杆菌（human-associated Bacteroides，HuBacteroides）——并结合多种环境参数，与通过定量聚合酶链式反应（quantitative PCR，qPCR）直接检测到的水源性病原体进行对比分析。检出轮状病毒（Rotavirus）的管井占比最高（40%），其次为志贺氏菌（Shigella，10%）、弧菌（Vibrio，10%）与致病性大肠杆菌（pathogenic E. coli，8%）。斯皮尔曼秩相关分析与灵敏度-特异性计算结果显示，部分而非全部指示物与环境参数的组合可用于预测病原体的存在情况。单次采样获取的依赖培养粪便指示菌数据无法预测细菌病原体，但按月采样并取年度平均值的可培养大肠杆菌数据，则可提升对总细菌病原体的预测效果。F+RNA噬菌体与轮状病毒既无相关性，对其检测灵敏度也不足，但可用于预测细菌病原体的存在。基于qPCR的大肠杆菌检测方法，是针对细菌病原体、轮状病毒以及所有病原体整体的最优指示物。鉴于在孟加拉国及其他特征相似的邻国，地下水被证实为腹泻病的重要传播源之一，因此亟需开发更高效的微生物污染管井筛查方法。