Salmonella: a genus of rod-shaped bacteria responsible for food poisoning, that is most likely to arise from food that has been kept in conditions that allow large num bers of bacteria to grow. Once contaminated food has been eaten, the bacteria enter the gut and multiply rapidly. Toxins are released as a result of the breakdown of bacterial cells and these cause gastro-enteritis. The symptoms of Salmonella food poisoning affect the person concerned 12 to 72 hours after consumption of the infected food. The resulting sickness and diarrhea are often accompanied by fever. In some people, even though the symptoms may have disappeared, bacteria remain in the body and continue to contaminate the feces. Such people are known as carriers and can easily contaminate food. Other species of Salmonella cause typhoid and paratyphoid fevers.