Nisin gold nanoparticles assemble as potent antimicrobial agent against Enterococcus faecalis and Staphylococcus aureus clinical isolates

Enterococci and staphylococci have the potency to acquire resistant to antibiotics and have emerged as serious nosocomial pathogens responsible for various diseases. The continuous seeking of new antimicrobials against these pathogens is the only way to avoid the rapid spreading of diseases. Controlled fabrication of existing antimicrobials with nanoparticles offers an alternative strategy to combat against these pathogens with an effective manner. In the present study, gold nanoparticles (AuNPs) were functionalized with nisin to kill a wide range of clinically isolated Enterococcus faecalis and Staphylococcus aureus strains. Nisin functionalized gold nanoparticles (NAuNPs) exhibited good inhibitory activity against all seven multidrug resistant (MDR) and eight non-MDR E. faecalis and S. aureus strains. Minimum inhibitory concentration of NAuNPs was >8-32 fold lower than nisin. Interestingly, antibiotic resistant was not observed by these pathogens up to 8 generation. TEM and AFM investigation revealed that, the antimicrobial action of NAuNPs appears to act in three sequential stages: membrane destabilization, pore formation, followed by intracellular fluid leakage. In addition, NAuNPs were non toxic and showed less hemolytic activity. These findings indicated that, the NAuNPs can be served as an alternative antimicrobial agent to treat a wide range of enterococcal and staphylococcal infections.

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