Department of Agriculture, Food, and Resource Sciences, University of Maryland Eastern Shoregrid.266678.b, Princess Anne, Maryland, USA.
United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Environmental Microbial and Food Safety Laboratory, Beltsville, Maryland, USA.
Microbiol Spectr. 2021 Oct 31;9(2):e0066921. doi: 10.1128/Spectrum.00669-21. Epub 2021 Oct 6.
Irrigation water sources have been shown to harbor foodborne pathogens and could contribute to the outbreak of foodborne illness related to consumption of contaminated produce. Determining the probability of and the degree to which these irrigation water sources contain these pathogens is paramount. The purpose of this study was to determine the prevalence of Salmonella enterica and Listeria monocytogenes in alternative irrigation water sources. Water samples ( = 188) were collected over 2 years (2016 to 2018) from 2 reclaimed water plants, 3 nontidal freshwater rivers, and 1 tidal brackish river on Maryland's Eastern Shore (ESM). Samples were collected by filtration using modified Moore swabs (MMS) and analyzed by culture methods. Pathogen levels were quantified using a modified most probable number (MPN) procedure with three different volumes (10 liters, 1 liter, and 0.1 liter). Overall, 65% (122/188) and 40% (76/188) of water samples were positive for S. enterica and L. monocytogenes, respectively. For both pathogens, MPN values ranged from 0.015 to 11 MPN/liter. Pathogen levels (MPN/liter) were significantly (0.05) greater for the nontidal freshwater river sites and the tidal brackish river site than the reclaimed water sites. L. monocytogenes levels in water varied based on season. Detection of S. enterica was more likely with 10-liter filtration compared to 0.1-liter filtration. The physicochemical factors measured attributed only 6.4% of the constrained variance to the levels of both pathogens. This study shows clear variations in S. enterica and L. monocytogenes levels in irrigation water sources on ESM. In the last several decades, Maryland's Eastern Shore has seen significant declines in groundwater levels. While this area is not currently experiencing drought conditions or water scarcity, this research represents a proactive approach. Efforts, to investigate the levels of pathogenic bacteria and the microbial quality of alternative irrigation water are important for sustainable irrigation practices into the future. This research will be used to determine the suitability of alternative irrigation water sources for use in fresh produce irrigation to conserve groundwater.
灌溉水源已被证明携带有食源性病原体，并可能导致与食用受污染农产品有关的食源性疾病爆发。确定这些灌溉水源中存在这些病原体的概率和程度至关重要。本研究旨在确定替代灌溉水源中沙门氏菌和李斯特菌的流行情况。在马里兰州东海岸，于 2016 年至 2018 年的两年间，从 2 个再生水工厂、3 个非潮汐淡水河流和 1 个潮汐咸水河采集了 188 个水样（ = 188）。使用改良的 Moore 拭子（MMS）通过过滤采集样本，并通过培养方法进行分析。使用三种不同体积（10 升、1 升和 0.1 升）的改良最大可能数（MPN）程序量化病原体水平。总体而言，分别有 65%（122/188）和 40%（76/188）的水样呈沙门氏菌和李斯特菌阳性。对于这两种病原体，MPN 值范围为 0.015 至 11 MPN/升。非潮汐淡水河流和潮汐咸水河的病原体水平（MPN/升）明显（0.05）高于再生水的水平。根据季节的不同，水中李斯特菌的水平也有所不同。与 0.1 升过滤相比，10 升过滤更有可能检测到沙门氏菌。测量的理化因素仅将两种病原体水平的 6.4%的约束方差归因于。本研究表明，马里兰州东海岸的灌溉水源中沙门氏菌和李斯特菌的水平存在明显差异。在过去几十年中，马里兰州东海岸的地下水位显著下降。虽然该地区目前没有经历干旱或水资源短缺的情况，但这项研究代表了一种积极的方法。努力调查替代灌溉水源中致病细菌的水平和替代灌溉水的微生物质量对于未来可持续的灌溉实践非常重要。这项研究将用于确定替代灌溉水源是否适合用于新鲜农产品灌溉，以保护地下水。
