Abstract
Considering the harmful effects and high spread of drug-resistantKlebsiella pneumoniae, many researchers have been trying to produce new antibacterial agents to combat the emergence of multidrug-resistant (MDR) strains of this bacterium. Recent progress in the nanomedicine field has provided opportunities for synthesizing unique nanoagents to battle MDR bacteria by targeting virulence and resistance signalling. The biocidal effects of 14.9 nm silver nanoparticles fabricated usingNostocsp. Bahar M (N-SNPs) and AgNO(3)were examined against drug-resistantK. pneumoniaeusing the agar well diffusion method. Transmission electron microscopy (TEM) was used to detect the ultrastructural changes caused by N-SNPs and AgNO3. To address the mode of action of N-SNPs and AgNO3, CAT, GPx, LDH and ATPase levels were assessed. The toxicity of N-SNPs and AgNO(3)was evaluated against themfD,flu,hly, 23S,hns,hcp-1,VgrG-1 andVgrG-3 genes as well as cellular proteins. N-SNPs showed the greatest inhibitory activity againstK. pneumoniae, with MIC and MBC values of 0.9 and 1.2 mg mL(-1), respectively. Furthermore, N-SNPs and AgNO(3)induced apoptotic features, including cell shrinkage and cell atrophy. N-SNPs were more potent bactericidal compounds than AgNO3, causing increased leakage of LDH and GPx activities and depletion of ATPase and CAT activities, resulting in induced oxidative stress and metabolic toxicity. Compared to AgNO3, N-SNPs exhibited the highest toxicity towards the selected genes and the greatest damage to bacterial proteins. N-SNPs were the most potent agents that induced bacterial membrane damage, oxidative stress and disruption of biomolecules such as DNA and proteins. N-SNPs may be used as effective nanodrugs against MDR bacteria.