Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 B-Ghent, Belgium; Laboratory of Food Microbiology and -Biotechnology, Department of Industrial Biological Sciences, Faculty of Bioscience Engineering, Ghent University, Campus Kortrijk, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium.
Laboratory of Food Microbiology and -Biotechnology, Department of Industrial Biological Sciences, Faculty of Bioscience Engineering, Ghent University, Campus Kortrijk, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium.
Int J Food Microbiol. 2014 Feb 3;171:21-31. doi: 10.1016/j.ijfoodmicro.2013.11.009. Epub 2013 Nov 18.
Eight Belgian lettuce farms located in the West Flanders were sampled to establish the relationships between levels of indicator bacteria, detection of enteric zoonotic pathogens and the temperature and precipitation during primary production. Pathogenic bacteria (PCR EHEC positives, Salmonella spp. or Campylobacter spp.) and indicator bacteria (total psychrotrophic aerobic plate count (TPAC), total coliforms, Escherichia coli, enterococci) were determined over a period of one and a half year from seedling leaves, peat-soil of the seedling, lettuce crops, field soil and irrigation water. Neither Salmonella isolates nor PCR EHEC signals were detected from lettuce although one out of 92 field soil samples contained Salmonella spp. and five soil samples provided PCR positives for EHEC virulence factors (vt1 or vt2 and eae gene). A low prevalence of Campylobacter (8/88) was noted in lettuce. It was shown that irrigation water is a major risk factor with regard to the bacterial contamination of the fresh produce as the water samples showed on a regular basis E. coli presence (59.2% of samples≥1CFU/100ml) and occasionally detection of pathogens (25%, n=30/120), in particular Campylobacter spp. The highest correlations between indicator bacteria, pathogens, temperature and the amount of precipitation were observed for the water samples in contrast to the soil or lettuce samples where no correlations were observed. The high correlations between E. coli, total coliforms and enterococci in the water implicated redundancy between analyses. Presence of elevated levels of E. coli increased the probability for the presence of pathogens (Campylobacter spp., EHEC and Salmonella spp.), but had a low to moderate predictive value on the actual presence of pathogens. The presence of pathogens and indicator bacteria in the water samples showed a seasonal effect as they tend to be more present during the months with higher temperature.
对位于西佛兰德省的 8 个比利时生菜农场进行了采样，以确定指示菌水平、肠致病性动物病原体检测与初级生产期间温度和降水之间的关系。在一年半的时间里，从幼苗叶片、幼苗的泥炭土、生菜作物、田间土壤和灌溉水中检测了病原菌（PCR EHEC 阳性、沙门氏菌或弯曲杆菌）和指示菌（总嗜冷需氧平板计数（TPAC）、总大肠菌群、大肠杆菌、肠球菌）。尽管从生菜中未检测到沙门氏菌分离株或 PCR EHEC 信号，但在 92 份田间土壤样本中有 1 份含有沙门氏菌，5 份土壤样本提供了 EHEC 毒力因子（vt1 或 vt2 和 eae 基因）的 PCR 阳性。在生菜中，发现弯曲杆菌的流行率较低（8/88）。研究表明，灌溉水是新鲜农产品细菌污染的主要危险因素，因为水样定期显示大肠杆菌存在（59.2%的样本≥1CFU/100ml），偶尔还会检测到病原体（25%，n=30/120），特别是弯曲杆菌。与土壤或生菜样本相比，水样本中指示菌、病原体、温度和降水量之间的相关性最高，而在土壤或生菜样本中则没有观察到相关性。水中大肠杆菌、总大肠菌群和肠球菌之间的高度相关性表明分析之间存在冗余。高水平大肠杆菌的存在增加了病原体（弯曲杆菌、EHEC 和沙门氏菌）存在的可能性，但对病原体的实际存在预测值较低。水样中病原体和指示菌的存在表现出季节性效应，因为它们在温度较高的月份更为常见。
