Role of oxygen dependent mechanisms in virulence of Salmonella typhimurium.

ABSTRACT

Catalase and superoxide dismutase (SOD) activities of five strains of S. typhimurium, namely SF 1546 LT2 71, SF 1835 C5 50, 386 SF 1591 Ra 20, SF 1567 Rd1, and an Indian strain were determined and correlated with their virulence profile. All five Salmonella strains exhibited catalase and SOD activities. No correlation was observed between either SOD and/or catalase activity and LD50 values of the isolates. Oxygen free radical generation elicited by macrophages, in the presence of virulent and avirulent salmonellae was also not statistically significant (P greater than 0.05), although the virulent species significantly resisted the macrophage bactericidal activity (P less than 0.05). It appears, therefore, that oxygen-dependent bactericidal mechanisms may not be important in phagocytic killing of S. typhimurium.