E. coli serotype O157:H7 is a gram-negative, rod-shaped bacterium and a cause of foodborne illnesses. Infection often causes severe haemorrhagic diarrhoea and stomach cramping, with little to no fever. Outbreaks have been associated with such foods as: undercooked beef, raw milk, unpasteurized juices, and raw produce. Transmission can also occur person-to-person or by coming into contact with contaminated water sources. The challenge of testing for this specific pathogen is the low level of its occurrence relative to other organisms in the sample. Enrichment and isolation media are not generally selective enough. Both factors make cultural identification and confirmation very difficult.