文摘

防止病原菌在牛奶和乳制品农场:分子生物学工具的有效性

作者(年代):卡洛斯AF奥利维拉

牛奶和乳制品在人类营养有重要的作用,特别是在生命的最初几年,一旦这些产品是高质量的蛋白质来源,碳水化合物,脂肪和矿物质盐生长所必需的。因此,它是至关重要的,确保完整性和内在人类食用的牛奶和乳制品质量。原料奶代表一个理想的生长介质几个微生物被确认为食源性病原体或作为牛乳房炎的病原体,如金黄色葡萄球菌、大肠杆菌、单核细胞增多性李斯特氏菌。在奶牛乳腺的炎症反应细菌依附和牛奶污染的增长是一个重要的原因。受污染的挤奶设备和工人的手也常见病原菌的传播来源在奶牛场环境中,导致潜在的健康风险。因此,在流行病学的角度来看,有必要使用分析方法来识别不仅奶牛场的病原微生物,但也各自在挤奶环境污染的来源。在奶制品和其他食品行业,致病微生物的测定已被分子进行常规技术,主要是聚合酶链反应(PCR),除了自动PCR系统如BAXTM [1]。这些方法非常有用的识别细菌物种,但他们不区分细菌的血统来自同一物种,这是需要在流行病学调查的情况下。基于dna的方法通常是建议打字的病原体l . monocytogenes和金黄色葡萄球菌等,因为他们可以评估不同来源的菌株的遗传关系,因此作为环境中的细菌控制指导。虽然DNA测序是最精确的方法来评估遗传微生物之间的关系,这种方法仅限于专业实验室; therefore its application in the routine analysis in the food industry is still expensive and not practical. As an alternative to sequencing methods, several molecular techniques have been used to differentiate lineages of pathogens, especially the ribo typing and the Pulsed-Field Gel Electrophoresis (PFGE). PFGE is considered the most effective technique for typing because of its simplicity, relative low cost, time efficiency and high discriminatory power, depending on the restriction enzymes employed. In recent years, the application of molecular techniques in dairy farms has markedly increased, thus providing several data on the incidence of pathogen isolates found in milkers, equipment, individual cow’s milk and bulk tank milk that were epidemiologically related. Those reports indicated that S. aureus and other pathogenic bacteria may not only be transmitted between cows in the same farm, but also disseminated among farms and different, unrelated regions. In a study conducted in Brazil, PFGE was used as a tool for identifying the diversity of S. aureus strains among different sites inside the dairy farms, and how they contribute for contamination of the bulk milk [2]. PFGE identification of clusters and pulsotypes at different periods of sampling shows the persistence of strains in the environment. Therefore, the use of molecular identification of pathogens in the milking environment could be useful for addressing specific control strategies, including regular monitoring of the sanitizing procedures in the milking environment of dairy farms. In conclusion, although PFGE would be useful to screen for pathogenic bacteria in milk and in the milking environment, further studies are needed to determine if the cost-benefit relationship of such technique would be appropriate for dairy operations worldwide. In addition, future research should focuses on the development of other molecular techniques that could be applicable for rapid, robust analysis of microorganisms in the environment of dairy farms, an area that currently seems to be a priority in the broad domain of the dairy science research.