Investigation of the activity of different nanoparticle forms of nisin on methicillin resistant staphylococcus aureus (MRsA) isolates

In this master's thesis, the antibacterial activity of nisin, which has been used safely as a food preservative for a long time, was investigated by microdilution method on clinical MRSA strains by functionalizing it with gold and silver nanoparticle systems in different sizes and forms. Multidrug resistance to existing agents in bacteria has become one of the most important global public health problems. Problems arising from limited, long and costly production processes, physicochemical properties and treatment inefficiencies of existing antibacterials, and cheap and effective new solutions have been sought, and the improvement and activation of existing antibacterials using nanotechnology has come to the fore. MRSA's are very important multidrug resistant infectious agents. The controlled production of current antimicrobials with nanoparticles offers an alternative strategy to effectively combat pathogens such as MRSA. Lactococcus lactis ssp. Nisin, a bacteriocin produced by Lactis, is a cationic antimicrobial peptide known to exhibit high antimicrobial activity against many gram-positive bacteria and foodborne pathogens. The therapeutic potential of nisin has the potential to be used synergistically with antibiotics and nanoparticular systems in the treatment of patients infected with antibiotic-resistant bacteria such as methicillin-resistant S.aureus as an alternative to conventional antibiotics. Metallic nanoparticles offer a new potential way to fight bacteria. Silver and gold nanoparticles are nanoparticular systems that have gained importance recently. In this study, the antimicrobial effects of nisin, silver and gold nanoparticles, alone and in combination with the antimicrobial peptide nisin of different shapes and sizes, on MRSA strains were demonstrated. As a result; silver nanoparticles showed more antibacterial activity than gold nanoparticles. Gold nanoparticles alone did not show antibacterial activity against any strain, while silver nanoparticles alone showed activity even at low concentrations. At very high concentrations, Nisin shows antibacterial activity on MRSA strains. In addition, as a result of the functionalization of the nanoparticles, increased antibacterial activity was observed compared to the activity of nisin alone. It is thought that these nanoparticular systems with nisin may be among the treatment options by elucidating with further studies.