Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology

Salmonella is the pathogenic agent of salmonellosis, a major cause of enteric illness and typhoid fever. Salmonella Typhimurium infects poultry causing significant losses, serovar 1, 4, [5], 12: i: - is considered a monophasic variant of S. Typhimurium that increasingly important as public health risk. A total of 58 Salmonella isolates were reidentified by slide agglutination test according to White-Kauffmann- Le Minor scheme. A duplex syber green real time PCR was applied for detection of genus Salmonella and S. Typhimurium using 16S rRNA and fliCgenes. All strains harbor 16S rRNA. Twenty one strains harborfliC gene that including S. Typhimurium (12), S. Kentucky ( 6) , S.1,4,[5],12:i:- (1) , S. Lagos (1) and S. Kedougou (1). A duplex Tagman real time -PCR was performed for differentiation between biphasic S. Typhimurium and monophasic variant 1,4,[5],12:i:- using fljB1,2 and fliB / IS200 in the Fli A. B intergenic region. Ten strains out of 12 S. Typhimurium harbor fljB1,2 however strain S1,4,[5],12:i:- don't possess this gene. While 13 strains were positive to fliB / IS200(12 S. Typhimurium and S 1,4,[5],12:i:-). The fliB / IS200 is specific gene for S .Typhimurium (biphasic and monophasic).These results indicate that two strains serologically confirmed to be S. Typhimurium and S.1,4,[5],12:i:- don't possess fljB1,2 and have fliB/ IS200genes are monophasic variants bya duplex Tagman real time -PCR. It was noticed that prolonged subculture and or repeat phase inversion method leads to formation of flakes that in turn cause wrongly serotyping identification. Real time {u2013}PCR is rapid and can be used to identifying and differentiation between biphasic and monophasic S.1, 4, [5], 12: i: - S. Typhimurium

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