Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2008
Publication Date: 1/1/2009
Citation: Gallegos-Robles, M., Morales-Loredo, A., Alvarez-Ojeda, G., Osuna-Garcia, J., Martinez, I.O., Ramos-Morales, L.H., Fratamico, P.M. 2009. Pcr detection and microbiological isolation of Salmonella spp. from bovine meat and cantaloupe. Journal of Food Science and Technology. 74(Nrl):M37-M40. Interpretive Summary: Salmonella species are an important cause of gastroenteritis, enteric fever, and septicemia, and infections are commonly transmitted through contaminated food, including meat, fruits, and vegetables. To minimize the occurrence of food-borne outbreaks, sensitive and rapid methods for detection of Salmonella are needed. A polymerase chain reaction (PCR) assay based on amplification of a region in a gene specific for Salmonella species (invA) was compared to a traditional microbiological technique to determine the sensitivity of both methods and to test for the presence of the pathogen in commercial bovine meat samples and on cantaloupe surfaces. Both methods showed the same level of sensitivity, detecting 1 CFU/25 g or ml of sample after enrichment for 24 h. Salmonella was detected in 4/50 naturally contaminated meat samples by the PCR compared to 3/50 samples by the microbiological method and in 9/20 cantaloupe rinse samples by the PCR compared to 11/20 samples by the microbiological method. Furthermore, results were obtained more rapidly using the PCR assay compared to the microbiological method. This study demonstrates the utility of the PCR method targeting the invA gene to determine the presence of Salmonella spp. in bovine meat and cantaloupe samples.
Technical Abstract: Salmonella species are an important cause of enteric fevers, gastroenteritis, and septicemia, and infection is commonly transmitted through contaminated food. In this study, the efficacy of the PCR technique based on amplification of a 267-bp region of the invA gene found in the Salmonella genus was compared to a microbiological technique, to determine the presence of this pathogen in commercial bovine meat samples and in cantaloupe surface rinses. Both methods showed the same level of sensitivity, detecting 1 CFU/25 g or ml sample after enrichment for 24 h. Furthermore, 50 commercial meat samples that were not artificially inoculated with Salmonella were analyzed. Salmonella was detected in three samples by the microbiological method, and these same three samples and an additional sample were positive by the PCR. Both methods were also used to test rinses of naturally contaminated cantaloupe surfaces, and the PCR method was more sensitive than the microbiological technique, confirming the presence of this pathogen on the cantaloupes. This study demonstrates the utility of the PCR, targeting the invA gene to determine the presence of Salmonella spp. in bovine meat and cantaloupe samples.