INHIBITION OF GROWTH OF BACTERIA IN STAPHYLOCOCCUS AUREUS AND PSEUDOMONAS AERUGINOSA CULTURES BY COPPER AND ZINC CATIONS, APPLIED AT PHYSIOLOGICAL CONCENTRATIONS

Aim. Evaluation of antibacterial effect of y-globulin fraction bound and free copper and zinc cations, applied in cultures of S. aureus and P. aeruginosa at physiological (micromolar) concentrations. Materials and methods. Day cultures of S. aureus or P. aeruginosa were transferred from agar to physiological solution, and cell suspension was prepared, containing approximately 10³ - 10⁴ CFU/ml. Samples of metal-complexes of y-globulin with copper and zinc cations (30 and 45 pg/ml), control y-globulins (30 and 45 pg/ml) and salt solutions of copper and zinc, cation content in those corresponded to the quantity of the metal, that had bound with the protein at the stage of metal-complex obtaining (75 ng/ml), were introduced into the suspension. The suspensions were incubated at 37°C for 6 hours, sampling and CFU count according to the accepted micromethod was carried out every 2 hours. By the end of incubation (6 hours of observation) the suspensions were transferred into nutrient broth, thermostated for 1 day at 37°C, transparency of the nutrient broth compared with control (sterile) was evaluated afterwards. Results. Toxic effect of copper and zinc cations is detected starting from the 3rd hour of observation in S. aureus culture. Viable bacteria are absent in the culture with zinc after 6 hours, with copper - after 4 hours of incubation, y-globulin, that had bound copper cations, reduces the quantity of viable cells compared with control protein by 11.9 - 33.0% (p<0.05 - 0.1) at 4 and 6 hours of incubation. In P. aeruginosa culture, toxic effect of copper cations manifests immediately after initiation of the culture and results in realization of complete bactericidal effect after 4 hours of observation. Zinc cations do not have such properties, y-globulin, that had bound copper cations, reduces the quantity of viable cells compared with control protein at 4 and 6 hours of incubation by 19.3 - 25.8 % (p<0.001). Conclusion. S. aureus bacteria, supported in physiological solution are subject to toxic effect of physiological (micromolar) concentrations of free copper and zinc cations, and also copper cations, bound by human serum y-globulin. P. aeruginosa bacteria under the same conditions experience toxic effect of copper cations (but not zinc), free as well as bound by human serum y-globulin. Whereas a full bactericidal effect is realized in S. aureus and P. aeruginosa cultures in the presence of free cations of copper.

S.aureus, P.aeruginosa, antibacterial effect, copper, zinc, S. aureus, P. aeruginosa