Acid tolerance, bile salts and serum resistance of Salmonella Gallinarum from hens

A total of ten Salmonella Gallinarum strains in log-phase of growth isolated from internal organs of dead hens with acute fowl typhoid were investigated for potential virulence factors. The strains differed in their acid tolerance, bile salts and serum resistance. S. Gallinarum cells were 70% resistant just 1 h post challenge at pH 2.0 and 0% at 4 and 24 h. When surviving at pH 2.5 and 3.0 it was found that the same cultures survived at these pH values much better than at pH 2.0. Half of the strains showed resistance to 20% and more than 20% bile salts, while the other half of strains showed resistance to 10% bile salts concentration. Seventy percent of the strains were resistant to blood serum from men and cattle, 60% to blood serum from women, 50% to blood serum from sheep, 40% to blood serum from swine and 90% to blood serum from chickens. This study established for the first time a range of apparently inherent tolerance in S. Gallinarum strains, and independently, that all of the strains S. Gàllinarum isolated from dead hens with acute fowl typhoid showed different acid tolerance, bile salts and serum resistance.