Pulsed-field gel electrophoresis genotyping of Salmonella gallinarum and comparison with random amplified polymorphic DNA

Salmonella gallinarum is gram-negative bacteria that cause fowl typhoid (FT) in chickens. Since the first outbreak of FT reported in 1992 in Korea, it has widely spread throughout the country. Today, FT is one of the most devastating diseases of poultry. The aim of the present study was to ascertain a genetic relationship among S. gallinarum isolates collected from different regions of Korea over a 10-year period. We examined a total of 38 isolates of S. gallinarum obtained in 29 regions of Korea from 1992 to 2001 including the 9R vaccine strain and the standard strain of S. gallinarum (ATCC 9184). The PFGE profiles produced 12 different patterns with the XbaI-digestion and 11 different patterns with the SpeI-digestion. The RAPD using URP-6 primers showed eight different genotypes with the same Salmonella isolates. The PFGE patterns of the 9R vaccine strain and ATCC 9184 of S. gallinarum were different from the identical type A, the most common genotype among field isolates in our study. In conclusion, a low genetic heterogeneity was observed among Korean S. gallinarum isolates. In addition, PFGE appeared to be a more accurate and reproducible method for genotyping of S. gallinarum isolates than RAPD.