DETECTION OF SALMONELLA-GALLINARUM AND S-TYPHIMURIUM DNA IN EXPERIMENTALLY INFECTED CHICKS BY POLYMERASE CHAIN-REACTION

DNA detection with polymerase chain reaction (PCR) as a mean of identi fying Salmonella infection in chickens was compared with the conventio nal culture procedure. DNA was extracted from organs of experimentally infected chicks with either S. Gallinarum or S. Typhimurium. The pair of primers used were those directed at the InvA gene. Bacteria isolat ion was done by inoculating the pre-enrichment media with samples. As was expected a 284 bp fragment DNA was amplified from extracted DNA of infected organs by PCR. The results of our studies indicate that the PCR method is more sensitive than the conventional culture procedure s ince we were able to detect both S. Gallinarum and S. Typhimurium DNA not only in samples positive for bacteria isolation but also in negati ve samples. It was possible to detect Salmonella DNA in 15 out of 20 o rgan samples from chicks infected with S. Gallinarum 21 hr after infec tion, but, only five were positive for bacteria isolation. Salmonella DNA was detected throughout the entire test period. The results of thi s study confirm that PCR is a useful tool for the detection of Salmone lla infection in poultry.