Interruption in membrane permeability of drug-resistant Staphylococcus aureus with cationic particles of nano‑silver.

The increasing drug-resistance pathogens among gram-positive bacterial species are becoming a major health concern nowadays. Over the past few years, the bactericidal efficacy of nano‑silver against some drug-resistant gram-positive bacteria has been established, however further investigation is needed to determine whether nano‑silver could be an option for the treatment of drug-resistant gram-positive microbial infections. The purpose of the present study was to determine the bactericidal efficacy of nano‑silver with its membrane destroying property using drug-resistant Staphylococcus aureus MTCC 3160. In the present study, bactericidal assessment of nano‑silver with different antibiotics was determined by agar well diffusion method. Interaction of nano‑silver towards bacterial membrane was carried to understand the probable bactericidal actions of nano‑silver, which was further confirmed by respiratory chain dehydrogenase, zeta potential, Scanning Electron Microscopy (SEM) and Gas Chromatography-Mass Spectrometry (GC-MS). The effect of nano‑silver on bacterial Deoxyribonucleic Acids (DNA) was evaluated by agarose gel electrophoresis. Bactericidal assessment of nano‑silver showed a very strong bactericidal action compare to antibiotics. The binding affinity of nano‑silver towards bacterial membrane induced loss of catalytic activity for respiratory chain dehydrogenases. Zeta potential, SEM and GC-MS analysis also revealed extensive damage to the bacterial cell membrane. Moreover, the analysis of agarose gel electrophoresis revealed that nano‑silver can enhance the decomposability of bacterial DNA, which was directly attached to the bacterial cell membrane. The present findings suggested that nano‑silver directly interact with the bacterial cell surface without the need to penetrate; and this distinctive property raises the hope that nano‑silver will remain an important bactericide in bacteria than antibiotics.