engleski

Bactericidal effect of zeolites against Gram-negative bacteria

INTRODUCTION: In view of the increasing resistance of bacteria towards available antibiotics, research efforts are focused to alternative disinfectants. E. coli and A. baumannii are one of the most multidrug-resistant bacteria. In this study, the antibacterial activity of some zeolites against pathogenic Gram-negative bacteria E. coli and A. baumannii was tested in water media. THE AIM: Antibacterial activity of natural zeolite – clinoptilolite enriched with silver and copper ions was investigated toward wildtype of E. coli DSM498, isolates of E. coli from a lake water in Serbia, and multi-drug resistant clinical isolate of A. baumannii. METHODS: Clinoptilolite-rich tuff (Z) from Zlatokop deposit was enriched with Cu(II) and Ag(I) by an ion-exchange procedure. The obtained Ag-Z and Cu-Z contained similar amounts of metal ions (~0.3 mmol Cu/Ag per 1 g of Z). The antibacterial tests were conducted in an effluent from wastewater treatment plant and in phosphate buffer solution using the solid/liquid ratio of 1:1000. RESULTS: Both zeolites showed bactericidal effect against studied bacteria: Ag-Z after 1h and Cu-Z after 3 h of contact. Bactericidal effect of Ag-Z and Cu-Z was more pronounced against E.coli. Leached concentrations of Cu and Ag after the experiments were below the maximum allowed concentrations for waters in Serbia (0.3 mg Cu dm-3 and 0.5 mg Ag dm-3). Additional investigation indicated that Cu(II) and Ag(I) leached from the zeolite lattice were responsible for the bactericidal activity. CONCLUSION: Concerning the bactericidal effect, Cu-Z and Ag-Z are promising disinfectants.

E. coli, A. baumannii, zeolite

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