PCR amplification products of Salmonella isolates analyzed. Lanes 2 through 5, fliB-fliA intergenic region of Salmonella serovar 4,5,12:i:−, serovar Typhimurium phage type LT2, serovar Typhimurium phage type DT U302, and serovar Brandenburg (3), respectively; lanes 6 and 7, phage type DT 104 and U302 162-bp specific amplicon of Salmonella serotype 4,5,12:i:− and serotype Typhimurium phage type DT U302, respectively (10); lane 1, molecular weight marker X (Roche Molecular Biochemicals); lane 8, 50-bp ladder (Amersham Pharmacia Biotech Inc.).