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Title: RAPID DETECTION OF SALMONELLA FROM HYDRODYNAMIC PRESSURE-TREATED POULTRY USING MOLECULAR BEACON REAL-TIME PCR

Author
item Patel, Jitu
item Bhagwat, Arvind
item Sanglay, Gabriel
item Solomon, Morse

Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2005
Publication Date: 6/22/2005
Citation: Patel, J.R., Bhagwat, A.A., Sanglay, G.C., Solomon, M.B. 2005. Rapid detection of Salmonella from hydrodynamic pressure-treated poultry using molecular beacon real-time PCR. Food Microbiology. 23(1):39-46. Available: http://authors.elsevier.com/sd/article/S0740002005000213

Interpretive Summary: Salmonella is one of the most frequent foodborne bacteria responsible for more than 1 million outbreaks and 500+ deaths every year in the United States. The detection of Salmonella is still primarily based on traditional culture methods recommended by the regulatory agencies that take several days to complete. With the polymerase chain reaction (PCR) technique, target DNA of bacteria is amplified after a series of amplification cycles which is detected by agarose gels or fluorescent probes. The PCR technique has increasingly been used in research for rapid, sensitive and specific detection of foodborne pathogens. We evaluated a real-time PCR assay to detect Salmonella in hydrodynamic pressure (HDP)-treated minced chicken. The sensitivity and accuracy of the assay was compared with the traditional USDA procedure. As few as 2 +/- 1 Salmonella cells could be detected from 25 g HDP-treated chicken following 16-18 h enrichment in buffered peptone water. Real-time PCR assay proved to be an effective method for Salmonella detection in HDP-treated chicken with high sensitivity and more importantly, a rapid and high-throughput detection in 18 h, compared to 3-8 days for the traditional microbiological methods. HDP treatment, which has been reported to reduce spoilage bacteria in various meats, was unable to kill pathogenic Salmonella in minced chicken.

Technical Abstract: A real-time PCR assay was evaluated to detect Salmonella in hydrodynamic pressure (HDP) treated chicken using molecular beacons probes available as a commercial kit (iQ-Check, Bio-Rad laboratories). The sensitivity and accuracy of the assay was compared with the conventional USDA microbiological procedure using artificially contaminated minced chicken. Chicken fillets were irradiated at 10 kGy to completely destroy any naturally occurring Salmonella. These fillets were minced and inoculated with as low as 2 +/- 1 CFU of S. Typhimurium per 25 g chicken. The minced chicken samples were vacuum packed in multilayer barrier bags, heat shrunk, and treated with HDP. Results showed that all inoculated samples (n = 36) were detected by the PCR assay and conventional USDA procedure. Similarly, all un-inoculated controls (n = 11) were negative by both, PCR assay and USDA procedure. As few as 2 +/- 1 CFU could be detected from 25 g HDP-treated chicken following 16-18 h enrichment in buffered peptone water. Real-time PCR assay proved to be an effective method for Salmonella detection in HDP-treated chicken with high sensitivity and more importantly, a rapid and high-throughput detection in 18 h, compared to 3-8 days for the conventional microbiological methods. HDP treatment, which has been reported to reduce spoilage bacteria in various meats, was unable to kill pathogenic Salmonella in minced chicken.