Identification & characterization of Shiga toxin-producing Escherichia coli isolates from patients with diarrhoea in Iran.

ABSTRACT

Background & objectives: Verotoxigenic Escherichia coli are important serotypes of enterohaemorrhagic E. coli (EHEC) subgroup that cause attaching and effacing lesions in enterocytes by producing verotoxins or shiga-like toxins resulting in haemorrhagic colitis (HC) and haemolytic uremic syndrome (HUS). The aim of this study was to detect these serotypes specially E. coli O157H7 in stool samples of patients with diarrhoea and identification of virulence genes (STX1, STX2, Hly and EAE) in Shahrekord-Iran area using PCR technique. Methods: Two hundred diarrhoeal stool samples of patients were collected through 2007-2008. Microbiological and biochemical examinations were done to detect the E. coli. Serological tests carried out to identify the O157 or O157H7 serotypes. Results: Of the 58 E. coli isolates, 16 (27.6%) were detected as STX1 carrying E. coli, four (6.9%) carrying STX2, eight (13.8%) carrying both STX1 and STX2, and 12 (20.7%) were Hly carrying E. coli, but none of the isolates contained EAE gene. None of the isolates were E. coli O157 or O157H7 serotypes. Interpretation & conclusions: Our results revealed that verotoxigenic E. coli isolates other than O157 serotype were involved in causing diarrhoea in Shahrekord-Iran.