Salmonella is a genus of rod-shaped, Gram-negative, non-sporeforming, predominantly motile bacteria belonging to the Enterobacteriaceae family. Salmonella spp. are one of the most common causes of food poisoning worldwide and have been isolated from most types of raw food (e.g. meats, eggs and plant products). Their high resistance to drying combined with a very high heat resistance once dried makes Salmonella a potential problem in most foods, particularly in dry and semidry products.
Food legislation in many countries includes limits on Salmonella – typically absence in 25 g of food.
Traditional microbiological methods for detection of Salmonella in food and animal feed require a total of up to 5 days to obtain a simple yes/no result. For products where a positive release is important, this means a considerable delay before those products can be released into the market. The requirement of food manufacturers for a quicker release of finished products and for cost savings calls for a change in these methods. Thus, rapid methods have become increasingly interesting. The general expectation for a rapid test is to be sensitive and specific, user friendly and cost effective.
Most individuals infected with Salmonella develop diarrhea, fever, and abdominal cramps 12–72 hours after infection. The illness usually lasts 4–7 days, and the majority of patients recover without treatment. However, in some cases, the diarrhea may be so severe that hospitalization is required. In these patients, the Salmonella infection may spread from the intestines to the blood stream and then to other body sites. This can result in death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness.