Differential Toxicity of Manganese for Virulent and Avirulent Group A Streptococci

Abstract
SUMMARY: Mn2+ depressed the rate and extent of multiplication of several virulent strains of group A beta-haemolytic streptococci (Streptococcus pyogenes), and caused a 6-12 hr increase in the lag phases of related avirulent strains. Several other cations did not exert such differential inhibitory effects. Ca2+ overcame the inhibitory effects of Mn2+ in both kinds of organism. In suspensions of virulent strains, Mn2+ depressed both nucleic acid and protein syntheses below the control values, but only nucleic acid synthesis was depressed in avirulent-organism suspensions; protein synthesis was largely unaffected. The oxidation of glucose was depressed below control values by Mn2+ to a much greater extent in virulent strains than in avirulent strains.