Rapid identification of shiga toxin-producing Escherichia coli (STEC) using electric biochips.

Shiga toxin-producing Escherichia coli (STEC) strains are pathogens that cause severe infections, especially in children. Although early data suggested that the STEC phenotype was linked to the O157 serotype, subsequent studies indicated no such strict phenotype-serotype correlation. Thus, it seems that only a test detecting stx1 and stx2 genes (responsible for Shiga toxin production) can provide unambiguous results in STEC identification. Here, we present a system for the rapid detection of the presence of o157, stx1, and stx2 genes, on the basis of an asymmetric polymerase chain reaction and subsequent detection of the amplification products on electric biochips. The whole test lasts less than 100 minutes, and allows for the accurate identification of the stx1 and stx2 genes and the presence of pO157 plasmid in a bacterial colony or in a liquid bacterial culture. The procedure is fully automated, and the only required manual activity is a chip exchange.