McLellan Sandra L, Daniels Annette D, Salmore Alissa K
Great Lakes WATER Institute, University of Wisconsin-Milwaukee, 600 E. Greenfield Avenue, Milwaukee, WI 53204, USA.
Appl Environ Microbiol. 2003 May;69(5):2587-94. doi: 10.1128/AEM.69.5.2587-2594.2003.
Escherichia coli isolates were obtained from common host sources of fecal pollution and characterized by using repetitive extragenic palindromic (REP) PCR fingerprinting. The genetic relationship of strains within each host group was assessed as was the relationship of strains among different host groups. Multiple isolates from a single host animal (gull, human, or dog) were found to be identical; however, in some of the animals, additional strains occurred at a lower frequency. REP PCR fingerprint patterns of isolates from sewage (n = 180), gulls (n = 133), and dairy cattle (n = 121) were diverse; within a host group, pairwise comparison similarity indices ranged from 98% to as low as 15%. A composite dendrogram of E. coli fingerprint patterns did not cluster the isolates into distinct host groups but rather produced numerous subclusters (approximately >80% similarity scores calculated with the cosine coefficient) that were nearly exclusive for a host group. Approximately 65% of the isolates analyzed were arranged into host-specific groups. Comparable results were obtained by using enterobacterial repetitive intergenic consensus PCR and pulsed-field gel electrophoresis (PFGE), where PFGE gave a higher differentiation of closely related strains than both PCR techniques. These results demonstrate that environmental studies with genetic comparisons to detect sources of E. coli contamination will require extensive isolation of strains to encompass E. coli strain diversity found in host sources of contamination. These findings will assist in the development of approaches to determine sources of fecal pollution, an effort important for protecting water resources and public health.
从粪便污染的常见宿主来源中获取大肠杆菌分离株，并通过使用重复外源性回文序列（REP）PCR指纹图谱进行特征分析。评估了每个宿主组内菌株的遗传关系以及不同宿主组之间菌株的关系。发现来自单个宿主动物（海鸥、人类或狗）的多个分离株是相同的；然而，在一些动物中，其他菌株出现的频率较低。来自污水（n = 180）、海鸥（n = 133）和奶牛（n = 121）的分离株的REP PCR指纹图谱各不相同；在一个宿主组内，两两比较的相似性指数范围从98%到低至15%。大肠杆菌指纹图谱的复合树状图并没有将分离株聚类到不同的宿主组中，而是产生了许多亚群（使用余弦系数计算的相似性得分约>80%），这些亚群几乎是某个宿主组所特有的。大约65%的分析分离株被归入宿主特异性组。使用肠杆菌重复基因间共有序列PCR和脉冲场凝胶电泳（PFGE）也获得了类似的结果，其中PFGE对密切相关菌株的区分度高于两种PCR技术。这些结果表明，通过遗传比较进行环境研究以检测大肠杆菌污染来源将需要广泛分离菌株，以涵盖污染宿主来源中发现的大肠杆菌菌株多样性。这些发现将有助于开发确定粪便污染来源的方法，这对于保护水资源和公众健康至关重要。
