Rapid detection of Salmonella from poultry by real-time polymerase chain reaction with fluorescent hybridization probes

Abstract

Detection of Salmonella by bacteriologic methods is known to be time consuming. Therefore, we have developed a real-time probe-specific polymerase chain reaction (PCR) to rapidly detect Salmonella invA gene-based PCR products from chicken feces and carcasses by a fluorescence resonance energy transfer assay. The sensitivity and the specificity of this system were determined as 3 colony-forming units ml(-1) and 100%, respectively. Overnight tetrathionate broth enrichment cultures of chicken feces and carcass samples were used in template preparation for PCR. Also, a standard bacteriology was performed (National Poultry Improvement Plan-U.S. Department of Agriculture, Bacteriological Analytical Manual-Food and Drug Administration Center for Food Safety and Applied Nutrition) for confirmation. Seventy-two cloacal swab, 147 intestine, and 50 carcass (neck) samples were examined. Thirteen (8.8%) and 25 (17%) of the intestinal samples were found to harbor Salmonella by bacteriology and PCR, respectively. Forty-five of 50 (90%) carcass samples were Salmonella positive by both methods. Salmonella was not detected from cloacal swab samples. Results indicate that this assay has the potential for use in routine monitoring and detection of Salmonella in infected flocks and carcasses.