Abstract The aims of this study were to verify the occurrence of Listeria monocytogenes in chicken at industrial slaughterhouse, the presence of virulence genes and genetic relationship among isolates, and evaluate the antimicrobial susceptibility. A total of 195 samples distributed in 36 carcasses after evisceration, 36 after chilling and 36 after packing, 43 carcasses cutting and 44 cuts after packaging, were collected. L. monocytogenes was found in 35 (17.9%) samples, especially in meat cuts, and samples collected after packing were the ones with higher rate of contamination (8.3%). Serotyping revealed the presence of three serovars: 1/2a (87%), 1/2c (8%) and 1/2b (5%). Macrorestriction profile with Apal at Pulsed-field gel electrophoresis (PFGE) showed 12 pulsotypes, and isolates from carcass and drumettes after packing and breast filet from cuts section showed high pulsotypes diversity. Regarding the profile of antimicrobial susceptibility, 100% of the isolates were sensitive to most antibiotics tested, except for clindamycin; 42% had intermediate resistance and 5% resistance. Isolation of L. monocytogenes in high levels in the chicken slaughtering line, as found in this study points to a potential risk associated, because the pathogen remains viable in the food throughout the cold chain that is used to commercialization. Still, the antimicrobial susceptibility monitoring is of interest of public health and our result shows that the isolates were susceptible to almost all antibiotics tested, indicating that treatment commonly used to control listeriosis infection is adequate.

中文翻译：

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鸡屠宰场单核细胞增生李斯特菌的发生、分离株间的亲缘关系及抗菌药敏感性评价

摘要 本研究旨在验证工业屠宰场鸡中单核细胞增生李斯特菌的发生情况、毒力基因的存在情况及分离株间的亲缘关系，并评价其抗菌药敏感性。共收集了195个样品，分布在36个去内脏屠体、36个冷藏后和36个包装后，43个屠体切割和44个包装后切割。单核细胞增生李斯特菌在 35 个（17.9%）样本中被发现，尤其是在切肉中，包装后收集的样本污染率较高（8.3%）。血清分型显示存在三种血清型：1/2a (87%)、1/2c (8%) 和 1/2b (5%)。在脉冲场凝胶电泳 (PFGE) 中使用 Apal 的宏观限制曲线显示 12 种脉冲型，包装后的屠体和小鸡的分离物和切割部分的胸肉显示出高脉冲型多样性。关于抗菌药物敏感性，100% 的分离株对大多数测试的抗生素敏感，克林霉素除外；42% 有中等抵抗力，5% 有抵抗力。在鸡屠宰线中分离出高水平的单核细胞增生李斯特氏菌，正如本研究中发现的那样，表明存在相关的潜在风险，因为病原体在用于商业化的整个冷链中仍然存在于食品中。尽管如此，抗菌药物敏感性监测仍是公众健康的兴趣所在，我们的结果表明，这些分离株对几乎所有测试的抗生素都敏感，这表明通常用于控制李斯特菌感染的治疗是足够的。