Submitted to: Methods in Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 26, 2007
Publication Date: January 3, 2008
Citation: Bhagwat, A.A., Patel, J.R., Chua, T., Chan, A., Cruz, S., Gonzalez, A., Gustavo, A. 2008. Detection of salmonella species in foodstuffs. Methods in Molecular Biology. 439:33-43.
Interpretive Summary: Current methods used to detect harmful bacteria (human pathogens) on food require at least 2 to 3 days and up to 1 week. Because of the short shelf-life of ready-to-eat foods and fresh produce, faster methods to detect the presence of human pathogens are needed. The industry and several law enforcement agencies such as FDA and FSIS also need the ability to test for human pathogens, such as Salmonella, on many samples in a short time. In this study, we describe a step-by-step protocol that we developed using cutting edge biotechnology. The new molecular method allows for near-instantaneous detection of the presence and number of Salmonella bacteria. It requires less than 24 hours and is compatible with planned screening of a large number of samples. Rapid detection of Salmonella spp. is a crucial step in keeping fruits, vegetables, and other ready-to-eat foods safe. Both the food industry and consumers will benefit from the results of this research.
Conventional methods to detect Salmonella spp. in foodstuffs may take up to one week. Considering the limited shelf life of ready-to-eat foods as well as fresh produce, rapid methods for pathogen detection are required. Real-time detection of Salmonella spp. will broaden our ability to screen large number of samples in a short time. This chapter describes step-by-step procedure using an oligonucleotide probe that becomes fluorescent upon hybridization to the target DNA (Molecular Beacon; MB) in a real-time polymerase chain reaction (PCR) assay. The capability of the assay to detect Salmonella species from artificially-inoculated fresh- and fresh-cut produce as well as deli-style meats is demonstrated. The method uses internal positive and negative controls which enable researchers to detect false-negative PCR results. The procedure uses the buffered peptone water for the enrichment of Salmonella spp. and successfully detects the pathogen at low level of contamination (2-4 cells/25 g) in less than 24 hours.