Identification of Listeria monocytogenes in cattle meat using biochemical methods and amplification of the hemolysin gene

Abstract In Brazil and in other countries of the world, studies have been conducted to identify Listeria monocytogenes in cattle meat that is preferably consumed undercooked and, when marketed without meeting strict phytosanitary requirements, may cause outbreaks of listeriosis. In the such, foodborne outbreaks, the methods used for the detection of the pathogen and the efficiency associated with them are crucial for the proper assessment. In this study, we used the techniques biochemical and molecular for identification of the L. monocytogenes isolated from 30 samples of the fresh beef, marketed in ten butchers’ shop of the free-fair from a municipality from the Bahia, Brazil. The results obtained from biochemical tests (catalase, motility, β-hemolysis and carbohydrate fermentation), as well as PCR analysis for the hly gene (hemolysin production is an important factor in the pathogenesis of listeriosis) revealed that 50% of butchers shops presented bovine meat contaminated with bacteria of the Listeria sp. and confirmed that 54.16% of the analyzed meat samples were positive for L. monocytogenes. This study highlights the importance of microbiological surveillance in free-fair to minimize the exposure of consumers to this foodborne pathogen.

摘要：在巴西及全球其他国家，已有多项研究针对单核细胞增生李斯特菌（Listeria monocytogenes）在牛肉中的检出情况展开——这类牛肉通常偏好半生食用，若销售时未满足严格的植物检疫要求，可能引发李斯特菌病暴发。在这类食源性暴发事件中，病原菌检测方法及其检测效能对准确的风险评估至关重要。本研究采用生化与分子生物学技术，对从巴西巴伊亚州某自治市自由集市10家肉铺采集的30份新鲜牛肉样本中分离得到的单核细胞增生李斯特菌进行鉴定。本研究通过过氧化氢酶试验、动力试验、β溶血试验及碳水化合物发酵等生化检测，以及针对hly基因的聚合酶链式反应（PCR）分析（溶血素的产生是李斯特菌病致病机制中的关键因素），结果显示：10家肉铺中有50%的摊位所售牛肉受到李斯特菌属（Listeria sp.）细菌污染，且经确认，所分析的30份牛肉样本中有54.16%呈单核细胞增生李斯特菌阳性。本研究强调了对自由集市开展微生物监测的重要性，以降低消费者暴露于该食源性病原菌的风险。