Abstract Listeriosis is a foodborne disease, with a high mortality rate, that predominantly affects the elderly. Under European Union legislation, EC 2073/2005, food business operators are encouraged to undertake sampling to ensure that the food processing environment, and required to ensure that food products, are free of Listeria monocytogenes. To determine the prevalence of L. monocytogenes in smaller food processing facilities in Northern Ireland, 24 companies submitted six processing environment swabs and two food samples every two months for eighteen months (July 2015 to November 2016) for L. monocytogenes examination. The prevalence of L. monocytogenes was 4.6% in food samples, and 6.3% in processing environment swabs. Over the duration of the study, 96 isolates of L. monocytogenes were obtained, one from each positive sample, except for two meat samples that had >100 cfu/g, where two isolates were obtained from each sample. No seasonality in occurrence of L. monocytogenes was seen for food isolates but significantly higher numbers of positive processing environment swabs were found in the warmer months of May, July and September (p = .007). Pulsed Field Gel Electrophoresis (PFGE) analysis revealed the presence of 27 pulsotypes; 9 pulsotypes were shared between different facilities and 9 were persistent. Based on a Combase predictive growth model, 77.5% (n = 130) of the foods tested were predicted to support the growth of L. monocytogenes. All of the isolates carried the pathogenicity genes inlA and actA and 71.4% carried qacH, which confers resistance to quaternary ammonium compounds which are frequently used in sanitizers. Whole genome sequencing of the isolates allowed multi-locus sequence typing to be undertaken. The data indicated that the sequence types identified included those with disease-causing ability, highlighting the disease-causing potential of the isolates.

中文翻译：

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北爱尔兰小型食品经营者的场所和产品中单核细胞增生李斯特菌的流行率和持久性

摘要 李斯特菌病是一种食源性疾病，死亡率高，主要影响老年人。根据欧盟立法 EC 2073/2005，鼓励食品经营者进行抽样，以确保食品加工环境以及食品产品不含单核细胞增生李斯特菌。为了确定北爱尔兰小型食品加工设施中单核细胞增生李斯特菌的流行情况，24 家公司每两个月提交 6 个加工环境拭子和两个食品样本，持续 18 个月（2015 年 7 月至 2016 年 11 月），以进行单核细胞增生李斯特氏菌检查。单核细胞增生李斯特氏菌在食品样品中的流行率为 4.6%，在加工环境拭子中为 6.3%。在研究期间，获得了 96 个单核细胞增生李斯特氏菌分离株，每个阳性样本中一个，除了两个 >100 cfu/g 的肉类样品外，每个样品都获得了两个分离株。对于食品分离株，单核细胞增生李斯特氏菌的发生没有季节性，但在 5 月、7 月和 9 月的温暖月份发现阳性处理环境拭子的数量显着增加（p = .007）。脉冲场凝胶电泳 (PFGE) 分析显示存在 27 种脉冲类型；9 种脉搏类型在不同设施之间共享，9 种是持续性的。根据 Combase 预测生长模型，预测 77.5% (n = 130) 的测试食品支持单核细胞增生李斯特氏菌的生长。所有分离株都携带致病基因 inlA 和 actA，71.4% 的分离株携带 qacH，这赋予了对常用于消毒剂的季铵化合物的抗性。分离株的全基因组测序允许进行多位点序列分型。数据表明，鉴定出的序列类型包括具有致病能力的序列类型，突出了分离株的致病潜力。