Direct extraction of bacterial plasmids from food for polymerase chain reaction amplification.

In this report we describe a simple and rapid technique using DNA affinity columns that permits direct extraction of bacterial plasmids from a variety of foods for polymerase chain reaction amplification. The procedure was used to detect virulent enteroinvasive Escherichia coli in several artificially seeded matrices, including seafoods, greens, dairy products, enrichment media, and water. Polymerase inhibitors present in both foods and enrichment media were removed efficiently.