Rapid Detection of Salmonella from Poultry by Real-Time Polymerase Chain Reaction with Fluorescent Hybridization Probes

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.Original Abstract: Debido a que la deteccion de Salmonella mediante metodos bacteriologicos emplea mucho tiempo, se desarrollo una prueba de reaccion en cadena por la polimerasa a tiempo real con sondas especificas para detectar el gen inv A de la Salmonella a partir de heces de aves y de canales mediante el analisis de transferencia de energia fluorescente por resonancia. La prueba mostro una sensibilidad de 3 unidades formadoras de colonias y una especificidad del 100%. Se emplearon muestras de heces y de canales, cultivadas durante la noche en caldo de tetrationato, como material inicial para la prueba de reaccion en cadena por la polimerasa. Se realizo la prueba bacteriologica estandar como prueba de confirmacion. Se examinaron 72 hisopos cloacales, 147 muestras de intestino y 50 muestras de canales (cuellos de aves). De la totalidad de las muestras intestinales, 13 (8.8%) y 25 (17%) fueron positivas a Salmonella mediante las pruebas bacteriologicas y de reaccion en cadena por la polimerasa, respectivamente. De las 50 muestras de canales, 45 (90%) fueron positivas a Salmonella mediante los dos metodos. No se detecto Salmonella a partir de las muestras de hisopos cloacales. Los resultados