Enterohaemorrhagic Escherichia coli (EHEC) is an emerging food borne pathogen associated with a number of outbreaks worldwide, and is a serious public health threat. The symptoms of the disease can range from mild diarrhoea to severe disease, such as haemorrhagic colitis (HC), and can result in life-threatening systemic complications such as haemolytic uremic syndrome (HUS). The O157:H7 serotype is traditionally associated with severe outbreaks, however, non-O157 serotypes are becoming a significant public health concern especially in European countries and in Australia. In Norway, an outbreak of EHEC disease of serotype O103:H25 (NIPH-11060424) showed particularly high rates of HUS.
The main goal of this study was to improve knowledge regarding interactions between EHEC strains and commensal bacteria in a setting where some of the environmental factors characteristic of the gastrointestinal tract were represented. To do so, the effect of coculture/ spent medium from various bacteria on gene expression in EHEC strains, the effect of the vitamin K-homologue menadione on Shiga toxin 2 (Stx2) production, and the interactions between Stx2 bacteriophages and various E. coli strains were investigated. The latter were studied in order to obtain more information about the host range of the Stx2 phage
