Synergistic Effects of Gold Nanoparticles Mixed with Gentamicin, Erythromycin, Clindamycin, Bacitracin, and Polymyxin B against Staphylococcus aureus, Staphylococcus saprophyticus, Staphylococcus epidermidis, Enterococcus faecium and Enterococcus faecalis

Background and Objective: The majority of bacterial infections are now treatable using different classes of antibiotics. However, the world has faced a challenge called antimicrobial resistance that will diminish most antibiotics' beneficial impacts. A valuable strategy to prevent this adverse phenomenon is to increase the antibacterial effects of antibiotics using various materials as antibiotic enhancers. The aim of this project was to investigate the synergistic effects of gold nanoparticles (with a concentration of ۱۰۰-۲۰۰ µg/mL, a size of ۱۶ nm, and an average zeta potential of -۵۴.۴ mV) and different antibiotics against some gram-positive cocci. Methods: Standard Kirby-Bauer methods were used to test the antimicrobial properties of different concentrations of gold nanoparticles mixed with MIC levels of gentamycin, erythromycin, clindamycin, bacitracin, and polymyxin B against ATTC strains of S. aureus, S. saprophyticus, S. epidermidis, E. faecium, and E. faecalis. Results: It was indicated that the ۲۵:۷۵ ratio of AuNPs with gentamicin led to a larger zone of inhibition against S. aureus, S. epidermidis, and E. faecalis compared with pure antibiotics. Moreover, this increase was found against E. faecalis when applying ۲۵:۷۵, ۵۰:۵۰, and ۷۵:۲۵ ratios of AuNPs with clindamycin. Similarly, an increase in the diameter of the zone of inhibition against S. epidermidis was observed when using ۲۵ μL AuNPs with ۷۵ μL bacitracin. Additionally, a synergistic antibacterial effect against S. saprophyticus was found when using AuNPs and polymyxin B with a ratio of ۵۰:۵۰. Conclusion: It was concluded that suitable concentrations of gold nanoparticles could enhance the antibacterial activities of antibiotics.

Keywords:

Antibacterial effects , Antibiotic resistance , Gold nanoparticles , Gram-positive cocci , نانوذرات طلا , مقاومت آنتی بیوتیکی , اثرات ضد باکتریایی , کوکسی های گرم مثبت