Metal nanoparticle antibacterial effect оn antibiotic-resistant strains of bacteria

The rapid formation of microbial resistance to modern antibacterial drugs requires to search for new, alternative therapies. It is known that some organisms, such as plants, algae, fungi, are able to convert inorganic metal ions into metal nanoparticles due to the recovery process carried out by proteins, sugars and metabolites contained in the tissues and cells of these organisms. At the same time, many plants (e.g., plantain, yarrow, wormwood, turmeric long, calendula, marsh bagulnik, etc.) and metals (copper, silver, gold, zinc, etc.) themselves have antibacterial properties, so that metal nanoparticles obtained by biological method, or via “Green” synthesis method, from extracts of such plants can become a current alternative to many modern antibacterial drugs. The antibacterial mechanism of action of nanoparticles depends on the type of microorganisms affected, as well as on the type of nanoparticles, their concentration, size, and how they are obtained. Based on this, the study of the antibacterial effect of nanoparticles is one of the promising directions of solving the problem of microbial antibiotic resistance. There was examined antibacterial effect of metal nanoparticles containing silver, copper and gold obtained by biological method from the salts of AgNO₃, CuSO₄, H[AuCl₄] metals, respectively, and the extract of the plant — turmeric long (lat. Curcuma longa) — related to the following bacteria strain collection: E. coli (ATCC 25922), S. aureus (ATCC 25923), MRSA (ATCC 38591) and polyresistant clinical strains isolated from patients of the Regional clinical hospital (Krasnoyarsk) — К. рneumoniae, strain 104, P. аeruginosa, strain 40, P. аeruginosa, strain 215, А. baumannii, strain 210, А. baumannii, strain 211. Study allowed to identify the minimum suppressive concentration of nanoparticles by the method of serial dilutions (MUK 4.2.1890-04) with azurin dye. It was proved that metal nanoparticles exhibit different antibacterial efficacy depending on the type of nanometals used and bacterial cultures. Copper nanoparticles have the highest antibacterial activity, and gold nanoparticles have the lowest. The most marked antibacterial effect was observed against clinical polyresistant strains. Metal nanoparticles can become an alternative to the currently known antibacterial drugs, but despite the high efficiency of nanoparticles against polyresistant to antibacterial drugs microorganisms in vitro, it is necessary to take into account their possible toxic effect on live tissues, which requires further study in experiments in vivo.