Colored enhanced TEM of a Salmonella sp. bacterium. The cell is rod-shaped (top left) with long hair-like flagellae used for motility. Salmonella bacteria belong to the Enterobacteriaceae family. They are Gram-negative bacilli bacteria that inhabit the human gut. Salmonella includes the species S.typhi and S.paratyphi, responsible for typhoid and paratyphoid fever in humans. Other serotypes are responsible for gastroenteritis or food poisoning. Different types of Salmonella are classified according to their antigenic nature; around 1800 serotypes of this bacteria have been identified. Magnification unknown.