Henriques A R, Gama L T, Fraqueza M J
Faculdade de Medicina Veterinária, CIISA, Universidade de Lisboa, Avenida da Universidade Técnica, Pólo Universitário, Alto da Ajuda, 1300-477 Lisboa. Portugal.
Faculdade de Medicina Veterinária, CIISA, Universidade de Lisboa, Avenida da Universidade Técnica, Pólo Universitário, Alto da Ajuda, 1300-477 Lisboa. Portugal.
Int J Food Microbiol. 2017 Feb 2;242:101-106. doi: 10.1016/j.ijfoodmicro.2016.11.020. Epub 2016 Nov 21.
Listeria monocytogenes isolates collected from final products and food contact surfaces of 10 ready-to-eat meat-based food products (RTEMP) producing industries were analyzed to relate their virulence-associated characteristics and genetic profiles with the hygiene assessment of those industries. Together with sample collection, an audit was performed to evaluate the implemented food safety management system and to investigate the specific audit requisites more associated to the occurrence of those L. monocytogenes serogroups frequently related with human disease. L. monocytogenes was present in 18% of the samples. The isolates (n=62) were serogrouped and detection of virulence-associated genes inlA, inlB, inlC and inlJ, and also plcA, hlyA, actA and iap was done by multiplex PCR. After this initial characterization, selected isolates (n=31) were submitted to antibiotic resistance testing by the disk diffusion method for the currently most used human and veterinary antibiotics and resistance was low. These isolates were also subtyped by pulsed-field gel electrophoresis. Genotyping and serogrouping of L. monocytogenes isolates revealed a genetically diverse population. Our data indicate that contamination of final products does not seem to be uniquely related to the sampled food surfaces. The occurrence of those L. monocytogenes serogroups more commonly associated with human disease in industries with a high hygienic audit classification could be the result of a previous identification of the pathogen, with an enforcement of the hygiene program without recognizing the real source of contamination. This reinforces the importance of a conjoined diagnosis using audit data and microbiological testing. Food safety management systems of those industries need improvement, particularly in cleaning and sanitizing operations, analytical control, preventive maintenance, personal hygiene and root cause analysis.
对从10个即食肉类食品（RTEMP）生产行业的最终产品和食品接触表面采集的单核细胞增生李斯特菌分离株进行了分析，以将其毒力相关特征和基因图谱与这些行业的卫生评估联系起来。在进行样本采集的同时，开展了一次审核，以评估所实施的食品安全管理体系，并调查与那些经常与人类疾病相关的单核细胞增生李斯特菌血清群的出现更相关的具体审核要求。18%的样本中存在单核细胞增生李斯特菌。对分离株（n = 62）进行血清分型，并通过多重聚合酶链反应检测毒力相关基因inlA、inlB、inlC和inlJ，以及plcA、hlyA、actA和iap。在进行了这一初步特征分析后，对选定的分离株（n = 31）采用纸片扩散法进行了目前最常用的人类和兽用抗生素的耐药性测试，耐药性较低。这些分离株还通过脉冲场凝胶电泳进行了亚型分析。单核细胞增生李斯特菌分离株的基因分型和血清分型显示出一个基因多样化的群体。我们的数据表明，最终产品的污染似乎并非唯一与采样的食品表面有关。在卫生审核分类较高的行业中，那些更常与人类疾病相关的单核细胞增生李斯特菌血清群的出现，可能是之前识别出该病原体的结果，在执行卫生计划时未认识到真正的污染源。这强化了结合审核数据和微生物检测进行联合诊断的重要性。这些行业的食品安全管理体系需要改进，特别是在清洁和消毒操作、分析控制、预防性维护、个人卫生和根本原因分析方面。
