Salmonella bacteria. Coloured scanning electron micrograph (SEM) of Salmonella bacteria. Flagella, thin thread-like structures used by the bacteria to move, are also seen. Salmonella bacteria can cause food poisoning when they are eaten in contaminated food such as raw eggs. Given the right conditions, they can multiply rapidly. Symptoms include abdominal pain, nausea, diarrhoea and vomiting. Typhoid is also caused by a salmonella typhi bacteria. Magnification: x8000 when printed at 10cm wide.