Salmonella sp. Coloured transmission electron micrograph (TEM) of a cluster of Salmonella sp. bacteria. The cells are rod-shaped with long hair- like flagellae. The cell at centre is undergoing cell division whilst the cells at centre left have just completed division. Salmonella bacteria belong to the Enterobacteriaceae family. They are Gram-negative bacilli bacteria that inhabit the human gut. Salmonella includes serotypes responsible for typhoid, paratyphoid fever, gastroenteritis, or food poisoning. Around 1800 serotypes have been identified. Negatively stained. Magnification unknown.