Table_1_Revisiting the Biological Behavior of Salmonella enterica in Hydric Resources: A Meta-Analysis Study Addressing the Critical Role of Environmental Water on Food Safety and Public Health.DOCX

The increasing number of studies reporting the presence of Salmonella in environmental water sources suggests that it is beyond incidental findings originated from sparse fecal contamination events. However, there is no consensus on the occurrence of Salmonella as its relative serovar representation across non-recycled water sources. We conducted a meta-analysis of proportions by fitting a random-effects model using the restricted maximum-likelihood estimator to obtain the weighted average proportion and between-study variance associated with the occurrence of Salmonella in water sources. Moreover, meta-regression and non-parametric supervised machine learning method were performed to predict the effect of moderators on the frequency of Salmonella in non-recycled water sources. Three sequential steps (identification of information sources, screening and eligibility) were performed to obtain a preliminary selection from identified abstracts and article titles. Questions related to the frequency of Salmonella in aquatic environments, as well as putative differences in the relative frequencies of the reported Salmonella serovars and the role of potential variable moderators (sample source, country, and sample volume) were formulated according to the population, intervention, comparison, and outcome method (PICO). The results were reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyzes statement (PRISMA). A total of 26 eligible papers reporting 148 different Salmonella serovars were retrieved. According to our model, the Salmonella frequency in non-recycled water sources was 0.19 [CI: 0.14; 0.25]. The source of water was identified as the most import variable affecting the frequency of Salmonella, estimated as 0.31 and 0.17% for surface and groundwater, respectively. There was a higher frequency of Salmonella in countries with lower human development index (HDI). Small volume samples of surface water resulted in lower detectable Salmonella frequencies both in high and low HDI regions. Relative frequencies of the 148 serovars were significantly affected only by HDI and volume. Considering that serovars representation can also be affected by water sample volume, efforts toward the standardization of water samplings for monitoring purposes should be considered. Further approaches such as metagenomics could provide more comprehensive insights about the microbial ecology of fresh water and its importance for the quality and safety of agricultural products.

越来越多研究报道环境水源中存在沙门氏菌（Salmonella），这表明其并非仅源自零星粪便污染事件的偶然发现。然而，针对非再生水源中沙门氏菌的相对血清型分布情况，学界尚未就其发生现状达成共识。
本研究采用限制性极大似然估计量拟合随机效应模型，开展比例元分析，以获取与非再生水源中沙门氏菌发生情况相关的加权平均占比及研究间方差。此外，本研究还通过元回归与非参数监督机器学习方法，预测调节变量对非再生水源中沙门氏菌检出频率的影响。
研究遵循信息源识别、筛选与资格审查三个连续步骤，从已识别的摘要及文章标题中完成初步文献遴选。本研究依据人群、干预、对照、结局（PICO）框架，提出与水生环境中沙门氏菌检出频率、已报道沙门氏菌血清型相对频率的潜在差异，以及潜在变量调节因素（样本来源、国家、样本体积）的作用相关的研究问题。
研究结果依据《系统评价与元分析首选报告条目》（PRISMA）进行规范报告。最终共检索到26篇符合资格的文献，涉及148种不同的沙门氏菌血清型。
根据本研究构建的模型，非再生水源中的沙门氏菌检出频率为0.19[置信区间：0.14；0.25]。水源类型被确定为影响沙门氏菌检出频率的最重要变量，其中地表水与地下水的估计检出频率分别为0.31%与0.17%。人类发展指数（Human Development Index，HDI）较低的国家，其水源中沙门氏菌的检出频率更高。在高、低HDI区域中，小体积地表水样本的沙门氏菌检出频率均更低。
148种血清型的相对频率仅受HDI与样本体积的显著影响。鉴于血清型分布亦会受水样体积的影响，应考虑推进用于监测目的的水样采集标准化工作。未来可采用宏基因组学等研究方法，更全面地揭示淡水微生物生态学特征，及其对农产品质量与安全的重要意义。