Abstract
Although many pathogens have recently received considerable attention, Salmonella remains among the leading sources of food-borne illness throughout much of the world. A poultry producer suffers losses due to Salmonella infection of the flock including loss of birds and production time. The present study was carried out to compare between the conventional bacteriological method and pre-enriched PCR assay for detection of Salmonella in chicken swabs samples The culture method can detect Salmonella in 6 samples out of 105 of examined samples under investigation with an incidence of 5.7 %, where by using PCR can detect 7 Salmonella positive samples out of 105 examined samples with an incidence of 6.7 %. Dendrogram or phylogentic tree of 5 isolated salmonella serotypes on RAPD-PCR analysis – PCR pattern similarity. The phylogentic tree was constructed applying UPGMA to matrix of similarity established from the combined data obtained by using three RAPD-PCR primers (1, 2, and primer 5) which give the best discrimination out of the six Primers used in the study. The numbers indicate the percentage of similarity among RAPD-PCR profiles based on pair wise band sharing as compared with the molecular weight of the marker (DNA ladder)..
it was found that Salmonella serotypes isolated chickens and environmental samples have different degrees of genetic similarity as follow; S. anatum with S. typhimurium (52 %), S. anatum with S. derby (57 %), S. anatum with S. kentucky ( 62 %), S. anatum with S. enteritidis ( 48 %). S. typhimurium with S. derby ( 67 %), S. typhimurium with S. kentucky ( 43 %), S. typhimurium with S. enteritidis ( 38 %). S. derby with S. kentucky ( 37 %) S. derby with S. enteritidis (33 %). S. kentucky with S. enteritidis (29%). These results indicate that there are a different degrees of polymorphism between the 5 serotypes under investigation from lower degree of genetic similarity between (29%) between S. kentucky and S. enteritidis to higher degree (67 %) between S. typhimurium with S. derby.

Key words: Key words: Salmonella- PCR -Molecular.