Abstract

The effect of various concentrations of divalent cations on survival of gonococci in liquid medium was studied. The growth of Neisseria gonorrhoeae was inhibited by manganous chloride in concentrations above 1 X 10(-5)mol/l while the growth of control organisms such as Neisseria meningitidis and Escherichia coli was not inhibited by the same salt even at 1 X 10(-2)mol/l. Copper sulphate, cobaltous nitrate, nickel chloride, and zinc sulphate also had deleterious effects on gonococci. Magnesium chloride at 1.5 X 10(-1)mol/l permitted the growth of gonococci. The toxicity of manganous chloride and copper sulphate in the liquid media was in some measure reduced by adding charcoal but not by adding starch. The significance of these findings is discussed in relation to the efficiency of primary isolation and transport media for gonococci.