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Abstract
healthy dairy cows; 86 diarrheic dairy cows; 24 apparently healthy calves and 15 diarrheic calves (age over one month) from Suez Canal area. All samples were subjected to bacteriological examination. Salmonella were recovered (18) from total samples (298) by (6.2 %). Serotyping of the Salmonella isolates revealed Salmonella enterica subsp. enterica serovar Typhimurium which considered the major cause of the Salmonella causing infection in dairy cows and calves by incidence of (38.8 %) of the total Salmonella isolates followed by Salmonella enterica subsp. III arizona (33.3 %) then Salmonella enterica subsp. enterica serovars Newport and Salmonella enterica subsp. enterica serovar Dublin also detected but in lower prevalence by percent 16.6 % and 11.1 % respectively. The most serovars commonly found in apparently healthy dairy cows was serovar Typhimurium and serovar Dublin (0.6 % and 1.2 % respectively), serovar Typhimurium and supsp. III arizona in diarrheic dairy cows (2.3 % and 4.7 %respectively) while in apparently healthy calve serovar Typhimurium and subsp. III arizona detected by percent 4.2 % in each while in diarrheic calves isolated subsp. III arizona by percent of (6.7 %), Serovars Newport and serovar Typhimurium by percent 20 % in each. Using polymerase chain reaction technique for detection of Salmonella invA gene that present only in Salmonella species as a rapid and more sensitive technique revealed 5 isolates give positive by PCR which were negative by conventional methods.The result of studying in vitro the sensitivity of four isolated Salmonella strains to 16 antimicrobial agents revealed that Salmonella isolates were highly sensitive to amikacin, ofloxacin and ernofloxacin and variable to chloramphenicol and gentamicin while show multidrug resistant to the most antibiotic used.
Key words: Salmonella; dairy cows and calves; invA gene; antimicrobial drug.