Artisanal cheese from southern Chile is made primarily by rural families who raise dairy cows and produce cheese as a way to add value to their milk. The most common cheese produced is chanco, a semi-hard cheese that is typically sold in unauthorized markets. The methods of chanco production do not always follow good manufacturing practices; however, the presence of Listeria monocytogenes contamination in this cheese has not been previously documented. To better understand production practices and L. monocytogenes contamination, 39 cheese producers were surveyed with regard to infrastructure, cleaning and sanitation, pest control, personal hygiene, training, raw materials, and manufacturing. During four sampling trips in 2016 (March, May, August, and November), 546 samples were collected (468 cheese samples and 78 milk samples). For producers that tested positive for L. monocytogenes, environmental monitoring was also conducted, for which 130 additional samples were collected. Presumptive L. monocytogenes isolates (N = 94) were further characterized and subtyped using standard techniques and qPCR-based species/subtype verification; a subset of 52 isolates were also subtyped by Pulsed Field Gel Electrophoresis (PFGE). L. monocytogenes was found in 19 cheeses (4.1%) from five producers (12.8%). The most frequent serotypes were 1/2b (48.9%), group 4B (4b, 4d, 4e) (45.7%), and serotype 1/2a (5.4%). Although no milk samples tested positive for L. monocytogenes, all cheese samples from two producers tested positive during two of the samplings. Distinct PFGE types were recovered from each facility, demonstrating persistence of certain subtypes of the pathogen that ultimately caused end-product contamination. Environmental monitoring of the five positive producers revealed a prevalence of L. monocytogenes ranging from 0 to 30%, with food contact surfaces having the highest incidence of this organism. The findings of this study contribute to the understanding of L. monocytogenes incidence in artisanal cheese in the region of southern Chile.

中文翻译：

---

将手工奶酪中的李斯特菌李斯特菌污染追溯到智利南部奶酪生产商的加工环境。

智利南部的手工奶酪主要由农村家庭生产，他们饲养奶牛并生产奶酪，以增加牛奶的价值。生产的最常见的奶酪是chanco，一种半硬奶酪，通常在未经授权的市场上出售。chanco的生产方法并不总是遵循良好的生产规范。但是，该干酪中没有李斯特菌污染李斯特菌。为了更好地了解生产实践和单核细胞增生李斯特菌污染，对39个奶酪生产商进行了基础设施，清洁和卫生，害虫控制，个人卫生，培训，原材料和制造方面的调查。在2016年的四次采样之旅（三月，五月，八月和十一月）中，收集了546个样本（468个奶酪样本和78个牛奶样本）。对于单核细胞增生李斯特氏菌检测呈阳性的生产者，还进行了环境监测，另外收集了130个样品。使用标准技术和基于qPCR的物种/亚型验证，进一步对推定的单核细胞增生李斯特菌分离株（N = 94）进行亚型鉴定。52个分离株的子集也通过脉冲场凝胶电泳（PFGE）进行了亚型化。在来自五家生产商（12.8％）的19种奶酪（4.1％）中发现了单核细胞增生李斯特菌。最常见的血清型为1 / 2b（48.9％），4B组（4b，4d，4e）（45.7％）和1 / 2a血清型（5.4％）。尽管没有牛奶样品对单核细胞增生李斯特氏菌呈阳性，但来自两个生产商的所有奶酪样品在两次采样中均呈阳性。从每个设施中回收了不同的PFGE类型，表明最终导致最终产品污染的病原体某些亚型的持久性。对五个阳性生产者的环境监测表明，单核细胞增生李斯特氏菌的患病率在0％至30％之间，食物接触表面的这种生物的发病率最高。这项研究的发现有助于了解智利南部地区手工奶酪中单核细胞增生李斯特菌的发生率。