Antimicrobial synergic effect of allicin and silver nanoparticles on skin infection caused by methicillin-resistant staphylococcus aureus spp

Background: Today, the commonly used antibiotics may more and more frequently be ineffective against multiple pathogens, due to the selection of resistant microbial strains. As a result, an effort to find a new approach for solving this issue has been considered. Aim: The aim of this study is to investigate antimicrobial properties of allicin, silver nanoparticles (Ag NPs) and their combination again skin infection caused by methicillin-resistant Staphylococcus aureus (MRSA) strains in an animal model. Materials and Methods: In vivo, the effects of allicin, Ag NPs and their combination were investigated on mice in which the skin infection was caused by MRSA strains. In animals, S. aureus colony-forming units (CFU)/mL were counted the 4(th) day after treatment. In vitro, minimum inhibitory concentration (MIC) of bacterial growth and minimum bactericidal concentration (MBC) of allicin, Ag NPs and their combination were determined by microdilution technique. Results: The results of in vitro assays showed that MIC of allicin and Ag NPs were 2.2 mg/mL and 5.6 mg/mL, respectively, and MBC of allicin and Ag NPs were 3.1 ppm and 7.5 ppm, respectively. However, MIC and MBC of allicin and Ag NPs together on MRSA strains were 0.4 mg/mL and 1.1 ppm, respectively. The results of in vivo tests on skin infection showed that bacteria counted for control, Ag NPs, allicin and their combination were 377 x 108, 80 x 106, 43 x 105, and 0 CFU/mL, respectively. Conclusion: The obtained results clearly indicated (for the first time, to the best of our knowledge) that allicin and Ag NPs, when used in combination, exhibited a synergistic activity. Therefore, the present results can be of interest in the future to improve the treatment of skin infections caused by MRSA strains.