THE MECHANISMS OF BACTERICIDAL ACTION IMPACT IN COMMON ANTIBACTERIAL EFFECTS OF METAL CATIONS IN CULTURE OF STREPTOCOCCUS PYOGENES

Aim. The work was performed with the purpose to study an inhibitory action of millimolar concentrations of divalent metal ions, which differ by primary mechanisms of their toxicity, on the culture of S.pyogenes. Materials and methods. Suspensions of S.pyogenes bacteria which contained 10⁸ CFU/ml were sown by the lawns into the standard Petri dishes coated with the supplemented Nutrient Agar. 30 min later the salt solutions of divalent metals were added by the 5 pl drops on the surfaces of the lawns with use of 36-channel stamp replicator. The salt solutions contained the metals tested at the concentrations ranged between 5x10^-3 M to 5x10^-1 M. Then the dishes with bacterial cultures were incubated for 24 hrs at 37°C followed by measuring diameter of the area of culture growth inhibition. The probes of material obtained from the centers of the stunting areas were passed into the centrifuge tubes with the supplemented Nutrient Broth, incubated for up to five days at 37°C and tested for the Broth clarity. Results. In presence of the metal concentrations ranged between 50 to 500 mM inhibitory action towards S.pyogenes bacteria was registered as relatively low due to the effects of copper or ferrous ions, as intermediate due to the presence of cobalt, nickel or manganese, and as high due to the effects of zinc ions. At the same time ferrous or copper ions demonstrated high bactericidal activity, zinc ions showed relatively low one, whereas manganese, nickel or cobalt were characterized by the lack of bactericidal action registered. Conclusion. Inhibitory action of heavy metal divalent ions on the lawns of S.pyogenes cultures probably includes bacteriostatic and bactericidal components which impact is determined by primary mechanisms of the ions toxicity.

S.pyogenes, bactericidal action, metal cations, S.pyogenes