Autio T, Hielm S, Miettinen M, Sjöberg A M, Aarnisalo K, Björkroth J, Mattila-Sandholm T, Korkeala H
Department of Food and Environmental Hygiene, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
Appl Environ Microbiol. 1999 Jan;65(1):150-5. doi: 10.1128/AEM.65.1.150-155.1999.
Sites of Listeria monocytogenes contamination in a cold-smoked rainbow trout (Oncorhynchus mykiss) processing plant were detected by sampling the production line, environment, and fish at different production stages. Two lots were monitored. The frequency of raw fish samples containing L. monocytogenes was low. During processing, the frequency of fish contaminated with L. monocytogenes clearly rose after brining, and the most contaminated sites of the processing plant were the brining and postbrining areas. A total of 303 isolates from the raw fish, product, and the environment were characterized by pulsed-field gel electrophoresis (PFGE). PFGE yielded nine pulsotypes, which formed four clusters. The predominating L. monocytogenes pulsotypes of the final product were associated with brining and slicing, whereas contaminants of raw fish were not detected in the final product. Air-mediated contamination in the plant could not be proved. In accordance with these results, an L. monocytogenes eradication program was planned. The use of hot steam, hot air, and hot water seemed to be useful in eliminating L. monocytogenes. None of the control samples taken in the 5 months after the eradication program was implemented contained L. monocytogenes.
通过对某冷熏虹鳟鱼（Oncorhynchus mykiss）加工厂不同生产阶段的生产线、环境和鱼进行采样，检测了产单核细胞李斯特菌的污染位点。监测了两批产品。含有产单核细胞李斯特菌的生鱼样本频率较低。在加工过程中，用盐水腌制后，被产单核细胞李斯特菌污染的鱼的频率明显上升，加工厂污染最严重的位点是腌制和腌制后区域。通过脉冲场凝胶电泳（PFGE）对从生鱼、产品和环境中分离出的303株菌株进行了分型。PFGE产生了9种脉冲型，形成了4个簇。最终产品中占主导地位的产单核细胞李斯特菌脉冲型与腌制和切片有关，而生鱼中的污染物在最终产品中未被检测到。无法证明工厂存在空气介导的污染。根据这些结果，制定了一个根除产单核细胞李斯特菌的计划。使用热蒸汽、热空气和热水似乎有助于消除产单核细胞李斯特菌。在根除计划实施后的5个月内采集的对照样本中均未检测到产单核细胞李斯特菌。
