Shiga toxin-producing Escherichia coli O157:H7 detected by multiplex PCR in culture and human feces

SALINAS GABRIEL; LUCERO ESTRADA CECILIA; ESCUDERO MARÍA ESTHER; LAZARTE OTERO VALERIA; VELÁZQUEZ LIDIA DEL CARMEN; ANA MARÍA STEFANINI DE GUZMÁN; RIGO HUGO; CORREA SILVIA

La Punta, San Luis

Jornada; XXVII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2009

Sociedad de Biología de Cuyo

Shiga toxin-producing Escherichia coli (STEC) causes symptoms from acute diarrhea to hemolytic uremic syndrome. The aim of the present study was to establish the detection limit (DL) of stx1 and stx2 genes of STEC by multiplex PCR (mPCR), from culture (C) and artificially contaminated human faces (HF).Two STEC strains were used: one local (1) and one reference (2) strains.To establish the DL in C, both strains were cultured in trypticase soy broth for 18 h at 37 °C. Then, serial dilutions were performed from 10e7 to 10e0 CFU/ml, and 1 ml of each dilution was tested by mPCR. To establish the DL in HF, 1 g of a pediatric sample was inoculated with 1 ml of each strain using inocula of 10e9 and 10e7 CFU/ml, and cultured in 9 ml of EC broth at 37 °C. Samples were taken for mPCR at different times: 0, 3, 6, 18 and 24 h. In C, the DL was 9 x 10e2 CFU/ml for strain (1) and 4,7 x 10e3 CFU/ml for strain (2). In HF, the stx2 gene was amplified at any tested time for both inocula. The stx2 gene was also detected by mPCR from the feces of a 3-year-old patient with diarrhea, after 2 h of EC enrichment. The mPCR on HF might reduce the diagnostic time of STEC in 48 h.