Evaluation of techniques for the detection of Salmonella SPP. in animal feed using real - timepolymerase reaction within a South African context

Abstract: Infection of animals by Salmonella can lead to conditions such as anorexia, abortion, diarrhoea, reproductive disorders and even death. In the case of dairy cattle and chickens, it can also cause a decrease in the production of eggs and milk along with contamination of these products. With some animals, such as pigs and cattle however, infection does not result in disease symptoms. Not only will the animals shed Salmonella in their faeces, resulting in further spread, but the bacteria can also be passed to the meat as well as equipment used during in the slaughter process. During this period, the animals can also cause infection in other animals and even humans. Animal feed is one of the main sources of Salmonella in animals. Testing of animal feed and the components that are used to make animal feed is important in preventing Salmonella infections. Conventional testing for the presence of Salmonella is a laborious process that require several days before a result is obtained. Considering the cost implications of keeping large quantities of feed for the time required to confirm the absence of pathogens, as well as the potential risk of contamination, it is important to find techniques that require less time. Real-time PCR is a technique that is increasingly being used for the detection of pathogens such as Salmonella not only in food and water, but also in animal feed. Real-time PCR has the advantage of being fast and very sensitive. Numerous protocols are available in literature, as well as commercial kits that can be used for the detection of Salmonella in various substances. Since none of these kits are locally produced, they invariably have to be imported from overseas. It is therefore important not only that the kit used perform well, but also that it comes at a reasonable price. Four commercial kits and a protocol obtained from literature were tested for their detection of Salmonella in soya meal, which is used in the production of animal feed. They were compared not only to each other with regards to performance, but also in regards to time required for reaction runs, cost and ease of use.D.Tech. (Environmental Health