Selective supplement for the isolation of E. coli O157:H7.

The principal cause of haemorrhagic colitis, and others significant human illnesses characterised by bloody diarrhoea and severe abdominal pain, is suppose to be Escherichia coli O157 . The selectivity is due to the high level of potassium tellurite who separes serogroup O157 f rom other E. coli serogroups and inhibits Providencia and Aeromonas spp. Cefixime is inhibitory to Proteus spp. Instead od the majority E. coli strains, this microorganism does not ferment sorbitol producing colourless colonies (brownish-yellow) in A. MaConkey Sorbitol.