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    J Food Prot. 2004 Dec;67(12):2833-8.

    Detection of tet(M) gene from raw milk by rapid DNA extraction followed by a two-step PCR with nested primers.

    Cenci-Goga BT, Crotti S, Costarelli S, Rondini C, Karama M, Bennett P.

    Department of Pathology and Microbiology, School of Medical Sciences, Bristol BS8 1TD, UK. cencigoga@unipb.it

    The likelihood that milk and milk products may act as a vehicle for antibiotic-resistant bacterial genes has become a concern to the food industry and a public health issue, and the demand for rapid tests has increased. The purity of DNA extracted from food samples is a key issue in the sensitivity and usefulness of biological analyses, such as PCR for pathogens and nonpathogens. A rapid, phenol-chloroform free method based on a modification of a sodium iodide DNA extraction, followed by a two-step PCR was developed for direct detection of the tet(M) gene in milk samples within a single working day. This study compares the proposed method with a traditional phenol solvent extraction method and with a commercial kit (QIAamp DNA blood mini kit, Qiagen). The three DNA extraction methods were used to ensure access to the tet(M) gene from 1 ml of raw milk, inoculated with a strain of Enterococcus faecalis, which carries the tet(M) gene. The proposed method, followed by a two-step PCR with nested primers specific for the tet(M) gene, was able to reach a detection limit below 10 CFU/ml in less than 4 h, including the two amplification cycles, thus outperforming in sensitivity and rapidity both the traditional and the commercial method.

    PMID: 15633698 [PubMed - indexed for MEDLINE]

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