Ecological prevalence, genetic diversity, and epidemiological aspects of Salmonella isolated from tomato agricultural regions of the Virginia Eastern Shore
Ecological prevalence, genetic diversity, and epidemiological aspects of Salmonella isolated from tomato agricultural regions of the Virginia Eastern Shore
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DOI：
10.3389/fmicp.2015.00415
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发表时间：
2015-05-07
影响因子：
5.2
通讯作者：
Brown, Eric W.
中科院分区：
文献类型：
--
作者：
Bell, Rebecca L.;Zheng, Jie;Brown, Eric W.
维吉尼亚州是美国第三大新鲜番茄产地。生长在弗吉尼亚州东岸的西红柿几乎每年都与沙门氏菌疾病有关。追溯意味着污染发生在收获前的环境中。为了更好地了解沙门氏菌在番茄农业环境中的生态位，在弗吉尼亚州的一个区域农业研究农场进行了为期2年的研究。环境样本，包括番茄（果实、花朵和叶子）、灌溉水、地表水和沉积物，在生长季节收集。使用改良的FDA-BAM方法分析这些样品是否存在沙门氏菌。采用分子分析法对样品进行筛选。超过1500个样本进行了测试。75个样本沙门氏菌检测呈阳性，产生230多个分离株。最常见的分离血清型是S. Newport和S. Javiana，脉冲场凝胶电泳产生39种不同的模式。在许多其他血清型中进一步强调遗传多样性，显示出多个PFGE亚型。对2010年收集的几种与番茄消费相关的临床分离株进行全基因组测序（WGS），结果显示环境分离株和临床分离株之间的单核苷酸差异非常小，表明其来源与沙门氏菌污染的番茄有关。在监测的两个生长季节收集的几乎所有分离株都来自地表水和沉积物源，这表明这些地点是该环境持续和地方性污染的长期水库。
Virginia is the third largest producer of fresh-market tomatoes in the United States. Tomatoes grown along the eastern shore of Virginia are implicated almost yearly in Salmonella illnesses. Traceback implicates contamination occurring in the pre-harvest environment. To get a better understanding of the ecological niches of Salmonella in the tomato agricultural environment, a 2-year study was undertaken at a regional agricultural research farm in Virginia. Environmental samples, including tomato (fruit, blossoms, and leaves), irrigation water, surface water and sediment, were collected over the growing season. These samples were analyzed for the presence of Salmonella using modified FDA-BAM methods. Molecular assays were used to screen the samples. Over 1500 samples were tested. Seventy-five samples tested positive for Salmonella yielding over 230 isolates. The most commonly isolated serovars were S. Newport and S. Javiana with pulsed-field gel electrophoresis yielding 39 different patterns. Genetic diversity was further underscored among many other serotypes, which showed multiple PFGE subtypes. Whole genome sequencing (WGS) of several S. Newport isolates collected in 2010 compared to clinical isolates associated with tomato consumption showed very few single nucleotide differences between environmental isolates and clinical isolates suggesting a source link to Salmonella contaminated tomatoes. Nearly all isolates collected during two growing seasons of surveillance were obtained from surface water and sediment sources pointing to these sites as long-term reservoirs for persistent and endemic contamination of this environment.