Salmonella enterica serovar Typhimurium isolates of phage types DT104 and DT104b are frequently associated with multiple antimicrobial resistance. We describe the characterization of a class I integron containing dfrA1 and aadA1, genes from two Salmonella serovar Typhimurium DT104b isolates. Genetic mapping located the integron to the bacterial chromosome in each case.