Meiri-Bendek I, Lipkin E, Friedmann A, Leitner G, Saran A, Friedman S, Kashi Y
Faculty of Food Engineering and Biotechnology, Technion, Haifa, Israel.
J Dairy Sci. 2002 Jul;85(7):1717-23. doi: 10.3168/jds.S0022-0302(02)74245-8.
Bovine mastitis caused by Streptococcus agalactiae is mainly subclinical and therefore can be diagnosed only in the laboratory. We developed a polymerase chain reaction (PCR)-based method for specific and sensitive detection of S. agalactiae in raw milk. The specificity of the PCR reaction is based on unique S. agalactiae DNA sequences within the 16S subunit of the rRNA genes. Two pairs of sequences were used as positive controls; general streptococci primers, which anneal to conserved areas within the 16S rRNA subunit gene, and primers, which anneal to sequences within bovine mitochondrial DNA. The method of detection includes selective enrichment of S. agalactiae in the milk sample, followed by DNA extraction using a rapid and simple procedure developed for this purpose, and specific PCR reaction with appropriate controls. The method enables the detection of one bacterium in 1 ml of raw milk. The method developed can be easily incorporated as part of routine screening of bulk milk collection tanks for early detection of infected cows in a herd.
无乳链球菌引起的牛乳腺炎主要为亚临床型，因此只能在实验室进行诊断。我们开发了一种基于聚合酶链反应（PCR）的方法，用于特异性和灵敏地检测原料乳中的无乳链球菌。PCR反应的特异性基于rRNA基因16S亚基内独特的无乳链球菌DNA序列。两对序列用作阳性对照；一对是与16S rRNA亚基基因保守区域退火的一般链球菌引物，另一对是与牛线粒体DNA序列退火的引物。检测方法包括在牛奶样品中选择性富集无乳链球菌，然后使用为此目的开发的快速简便程序提取DNA，并进行带有适当对照的特异性PCR反应。该方法能够检测1毫升原料乳中的一个细菌。所开发的方法可轻松纳入原料乳收集罐的常规筛查，以便早期检测牛群中受感染的奶牛。
