Laboratório de Microbiologia e Controle de Alimentos, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul (ICTA/UFRGS), Av. Bento Gonçalves 9.500, prédio 43212, Campos do Vale, Agronomia, CEP: 91501-970, Porto Alegre, RS, Brazil.
Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, Campus Universitario de Espinardo, 30100, Murcia, Spain.
Food Microbiol. 2017 Aug;65:105-113. doi: 10.1016/j.fm.2017.02.003. Epub 2017 Feb 7.
Irrigation water has been recognized as an important microbial risk factor for fruits and vegetables in many production areas, but there is still a lack of information about how the microbiological quality of different irrigation water sources and climatic conditions influence the safety of vegetables produced in Brazil. This study evaluated the distribution of generic E. coli and the prevalence of E. coli O157:H7 in two different water sources (ponds and streams bordering farmlands and urban areas) used for irrigation and on commercially produced lettuces in Southern Brazil. We also evaluated the effect of agricultural factors and meteorological conditions in the potential contamination of water and produce samples. A longitudinal study was conducted on four farms during a year (July 2014 to August 2015). The results showed generic E. coli prevalence of 84.8% and 38.3% in irrigation water samples and on lettuces, respectively, indicating irrigation water as an important source of contamination of lettuces. No significant differences were detected in the counts of E. coli between the two different surface water sources. The climatic conditions, particularly rainfall and environmental temperature, have influenced the high concentration of E. coli. The highest loads of E. coli in irrigation water and on lettuces were found during the warmest time of the year. E. coli O157:H7 was detected by qualitative polymerase chain reaction (qPCR) in 13 water samples but only 4 were confirmed by isolation in culture media.
灌溉水已被认为是许多生产地区水果和蔬菜的一个重要微生物风险因素，但关于不同灌溉水源和气候条件的微生物质量如何影响巴西生产的蔬菜的安全性，仍缺乏信息。本研究评估了两种不同水源（农田和城市边缘的池塘和溪流）中用于灌溉的水中普通大肠杆菌的分布和大肠杆菌 O157:H7 的流行情况，以及在巴西南部商业生产的生菜中的分布情况。我们还评估了农业因素和气象条件对水源和农产品样本潜在污染的影响。在一年（2014 年 7 月至 2015 年 8 月）期间对四个农场进行了纵向研究。结果表明，灌溉水中普通大肠杆菌的流行率分别为 84.8%和 38.3%，生菜上的流行率分别为 84.8%和 38.3%，表明灌溉水是生菜污染的重要来源。两种不同地表水水源之间的大肠杆菌计数没有显著差异。气候条件，特别是降雨量和环境温度，影响了大肠杆菌的高浓度。在一年中最温暖的时期，灌溉水中和生菜上的大肠杆菌负荷最高。通过定性聚合酶链反应（qPCR）在 13 个水样中检测到大肠杆菌 O157:H7，但仅通过在培养基中的分离在 4 个水样中得到证实。
