A total of 213 milk samples from clinically mastitic cattle cows were collected from different Governorates of Egypt and
transferred in ice box as soon as possible to Bacteriological lab. in Animal Reproduction Research Institute (ARRI) in
Giza Governorate (AL-Haram) for bacteriological examination of most important pathogens causing clinical mastitis with
special references for isolation and strict identification of Salmonella species. All samples were collected during the
period from December 2016 till July 2017 from governorates of Egypt. The bacteriological investigations revealed that 8
(3.7%) of Salmonella isolates were identified biochemically from all examined samples. Serological study showed that a
total of 5 (2.3%) of Salmonella isolates were typed as Salmonella Typhimurium. Two strains of Salmonella Typhimurium
were isolated singly in the rate of (0.93%) from all examined samples, also another two strains of Salmonella
Typhimurium were isolated mixed with Staph aureus in the rate of (0.93%), meanwhile only one strain of same species
was isolated mixed with E.coli in the rate of (0.47%). Cefiquinom and Enrofloxacin were sensitively in the rate of (100%),
Ampicillin, Chloraphincol, Cloxacillin were resistance in the rate of (100 %) to Streptomycin and Amoxicillin. The
molecular examination confirmed that all 5 examined serotyped strains were Salmonella Typhimurium. Virulence genes
invA, hilA, avrA, were detected in examined sample by 100%, meanwhile sopE, ssaQ, and fimH genes were not detected
by zero%. The objectives of the present study was to investigate the occurrence of Salmonella serotypes as well as to
determine the frequency distribution of Six virulence genes (invA, hilA, avrA, ssaQ, sopE and fimH) in salmonella
isolates from cattle clinical mastitic milk, in addition to determine the drugs of choice for treatment of most Salmonella
strains causing cattle clinical mastitis.