Characterisation of Shiga toxin-producing Escherichia coli (STEC) isolated from seafood and beef

Shiga toxin-producing Escherichia coli (STEC) strains isolated in Mangalore, India, were characterised by bead-enzyme-linked immunosorbent assay (bead-ELISA), Vero cell cytotoxicity assay, PCR and colony hybridisation for the detection of stx(1) and stx(2) genes. Four strains from seafood, six from beef and one from a clinical case of bloody diarrhoea were positive for Shiga toxins stx(1) and stx(2) and also for stx(1) and stx(2) genes. The seafood isolates produced either stx(2) alone or both stx(1) and stx(2), while the beef isolates produced stx(1) alone. The stx(1) gene of all the beef STEC was found to be of recently reported stx(1)c type. All STEC strains and one non-STEC strain isolated from clam harboured EHEC-hlyA. Interestingly, though all STEC strains were negative for eae gene, two STEC strains isolated from seafood and one from a patient with bloody diarrhoea possessed STEC auto agglutinating adhesion (saa) gene, recently identified as a gene encoding a novel autoagglutinating adhesion. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.