Abstract

GALLI, L.; LEOTTA, G. A.; GUGLIADA, M. J.  and  RIVAS, M.. In silico analysis of the capability of two polimerase chain reaction techniques for stx gene detection. Rev. argent. microbiol. [online]. 2008, vol.40, n.1, pp.9-12. ISSN 0325-7541.

Shiga toxin-producing Escherichia coli is an emergent pathogen, being the Shiga toxin (Stx) the main virulence factor. These toxins are classified into 6 types (1, 2, 2c, 2d, 2e and 2f) and 22 variants. In Argentina, two PCR for stx gene detection, PCR-MK and multiplex-PCR, were validated. The aim of this work was to analyze, by using bioinformatic tools, the stx variants that could be amplified by these PCRs, and to experimentally show the amplification of 8 stx variants. Twentyfive nucleotide sequences were collected from GenBank corresponding to 21 stx variants. The BLAST 2 sequences program was used to analyze the complementarities between the nucleotide sequence of the variants and the primers corresponding to the PCR studied. PCR-MK could detect types stx₁, stx₂, stx_2c, stx_2d and stx_2f, but not type stx_2e and three type stx_2c variants. On the other hand, the multiplex-PCR could detect types stx₁, stx₂, stx_2c, stx_2d, but not stx_2e and stx_2f types. It was experimentally determined that both PCRs can detect those variants that cause severe disease in humans.

Keywords : Escherichia coli; Shiga toxin; Stx; PCR; Bioinformatics.

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