In this study we characterized, using genotyping and phenotyping methods, isolates (n=33) from septicaemia outbreaks in swine herds as well as isolates (n=33) recovered from healthy animals at slaughter. We determined the antimicrobial agents resistance profiles using 24 different antimicrobial agents by the disk diffusion on agar method, the phage type, the plasmid profiles and the PFGE profiles using Xbal and Spel as restriction enzymes for each isolates. Resistance to as much as 10 antimicrobial agents was found in both categories of isolates. A greater number of PFGE genotypes was observed in isolates from septicaemia. Various phage types were identified in both groups of isolates. Among the DT104 phage type, many genetic clusters were identified. Analysis of plasmid profiles indicated that septicemic strains possess higher molecular weight plasmids than asymptomatic isolates. These results indicated that strams associated with septicaemia belong to various genetic lineages and suggest that virulence traits are associated with plasmid profiles of strains. Our results also suggest that the genetic diversity of Salmonella DT104 might be higher in North America if we consider results of similar studies in Europe.