Salmonella is the most frequently reported cause of foodborne illness. These gram-negative, rod-shaped bacilli can cause diarrhoea, vomiting, fever, chills and cramps, and are especially dangerous to the elderly and infants. A variety of raw and unprocessed foods have been found to carry Salmonella spp., such as raw meat, poultry and eggs, shellfish, and in certain fruits, including watermelon and cantaloupe. There are over 2,000 serotypes in the Salmonella family and all strains and species are pathogenic to humans. In order to identify and isolate the many serotypes from other closely related bacteria, a test must be able to cover all serovars of Salmonella without detecting other closely related bacteria — a very delicate balancing act.