RIBOTYPES OF SALMONELLA-ENTERICA SEROVAR GALLINARUM BIOVARS GALLINARUM AND PULLORUM

Ninety-four isolates of Salmonella enterica serovar Gallinarum biovar pullorum and forty-one isolates of biovar gallinarum were ribotyped using the enzymes, HindIII, EcoRI and SmaI, and a digoxigenin-labelled E. coli-derived rRNA probe. Using HindIII, 13 profile types were observed within biovar gallinarum and 12 within biovar pullorum. The most common types accounted for 39% of biovar pullorum isolates and 47% for biovar gallinarum. EcoRI digests revealed two profile types within biovar pullorum, one accounting for 96% of the isolates, and three EcoRI profiles within biovar gallinarum, with 81% of the isolates belonging to the dominant type. Using SmaI, biovar pullorum showed two profile types with 94% of the isolates belonging to the dominant one, while SmaI digestion revealed only one ribotype within biovar gallinarum. The SmaI ribotype of biovar gallinarum was identical to the less common of the two SmaI types in biovar pullorum. Two of the HindIII profile types were seen in both biovars. The two biovars did not share any of the EcoRI profiles. Numerical analysis based on the ribotypes revealed a 94% similarity between the two biovars, but they clustered separately in a similarity dendrogram, underlining the existence of two different biovars. The results indicate that ribotyping, especially using EcoRI, may be useful in separating biovars gallinarum and pullorum. The ribotypes obtained with isolates from different countries indicated that different clones of biovar gallinarum might exist in different regions.