Salmonella in the bloodstream. Computer illustration of a Salmonella sp. bacterium (centre) amongst red blood cells (red) in a blood vessel. The presence of bacteria in the blood (bacteraemia) is always abnormal. They can enter the bloodstream as a complication of infections or surgery, or due to foreign bodies entering a blood vessel, such as needles in drug use. Salmonella is a major cause of food poisoning (salmonellosis) in humans, most commonly caught from infected pork, poultry and eggs. Symptoms include fever, chills, severe diarrhoea and vomiting. Treatment is with antibiotics.