Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver...

Area of Science:

• Nanotechnology
• Microbiology
• Materials Science

Background:

• Antibiotic resistance is a growing global health threat.
• Silver nanoparticles (AgNPs) show promise in combating resistant bacteria.
• The antibacterial mechanisms of AgNPs, particularly their charge, require further elucidation.

Purpose of the Study:

• To investigate the antibacterial effects of positively charged silver nanoparticles (AgNPs) on Staphylococcus aureus.
• To examine the ultrastructural changes induced by AgNPs in bacteria.
• To propose a mechanism for the antibacterial action of AgNPs.

Main Methods:

• Aberration-corrected transmission electron microscopy (TEM) was used to visualize bacterial ultrastructure.
• Positively charged silver nanoparticles with an average size of 1 nm were employed.
• Methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) were used as model organisms.

Main Results:

• AgNPs induced thinning and permeabilization of the bacterial cell wall.
• Destabilization of the peptidoglycan layer and leakage of intracellular contents were observed.
• Bacterial cell lysis was a direct consequence of AgNP treatment.
• AgNPs were hypothesized to initially target teichoic acids and cell wall glycopolymers.

Conclusions:

• Positively charged silver nanoparticles effectively induce cell lysis in Staphylococcus aureus.
• The proposed mechanism involves initial binding to cell wall components, leading to structural damage.
• Further research is needed to define the molecular mechanisms underlying AgNP antimicrobial activity.