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Abstract In this study a total number of 591 diarrhoeic cow and buffalo-calves as well as 55 apparently normal cow and buffalo-calves were subjected to bacteriological examination for isolation of Salmonella spp. The results revealed the isolation of salmonella from 59 out of 646 feacal samples representing the percentage of 9.75%. Salmonella typhimurium was the most predominant spp among the isolates (25), then Salmonella anatum (14), Salmonella entritidis (8), Salmonella meleagridis (7), Salmonella dulin (6) and Salmonella infantis (4). Virulence tests were applied for detection of microorganism characteristics including: motility test, invasion to Hela cells and heamagglutination pattern in RBCs of different animal species. Finally Polymerase Chain Reaction was applied to improve rapid, sensitive and specific diagnostic method for detection of such organism in calves and the results were as follow: Concerning motility test, the results revealed that all S. typhlmurium, S. dublin and S. anatum associated with diarrhoea were motile. Other Salmonella serovars gave variable results. Testes for invasion to Hela cells indicated that all Salmonella serovars were positively invasive to Hela cells after 3 hrs incubation. Heamagglutination pattern of Salmonella in RBCs of different animal species indicated that the majority of salmonella strains that had HA activity were (MRHA) type with bovine, sheep, G. pig, chicken and human RBCs. Concerning the use of PCR assay the results showed that, PCR products of Salmonella typhimurium include positive control, resulted in 243 bp amplified fragments and no amplified DNA fragments obtained from non Salmonella spp. And finally in this study the results revealed that application of PCR assay is important to SUMMARY 09 develop a highly sensitive and specific diagnostic method for rapid detection of Salmonella spp. in calves to help the complication arising from an outbreak of salmonellosis in a herd as well as it need 24 hours for results obtaining whereas it needs from 5-7 days to identify Salmonella spesies by culture methods. |