Biosynthesized Silver Nanoparticles as an Environmental-Friendly Antibacterial Nanosystem against Methicillin-resistant Staphylococcus Aureus

Antimicrobial resistance is a global health threat resulting in increased morbidity and mortality. Methicillinresistant staphylococcus aureus (MRSA) is one of the leading multi-drug resistant (MDR) pathogens causing a wide spectrum of infections. MRSA has become resistant to most antibiotics such as beta-lactams, vancomycin and glycopeptide antibiotics. Thus, alternative therapeutic approaches to conventional antibiotics have been investigated. These include phage therapy, antimicrobial peptides, natural products and nanoparticles. Nanotechnology has become a promising alternative to overcome MDR infections. Metallic nanoparticles possess inherent antimicrobial properties and they have been widely studied as antibacterials. Silver nanoparticles (AgNPs) have been shown to have antibacterial activity against a plethora of microorganisms including MDR pathogens such as MRSA. Traditional methods have been employed for the synthesis of AgNPs, however, due to hazardous waste, increased consumption of materials and detrimental effects on public health, green synthesis has been proposed as an alternative. Green synthesis is based on the use of bacteria, fungi, yeast and plants for the bioreduction of silver nitrate to produce AgNPs. Biosynthesized AgNPs have been investigated in several studies as antibacterial nanosystem to overcome MRSA infections. Studies showed that the biosynthesis of AgNPs offer better controllability over their physicochemical properties such as shape and size which in turn enhance their antimicrobial activity. Moreover, the production of biocompatible AgNPs in a single step process with less toxic byproducts render them superior to synthetic AgNPs. This review highlights various green synthesis approaches and assess the efficacy and safety of AgNPs as antibacterials against MRSA.