Anti-biofilm Activity of Synthesized Silver Nanoparticles Using Asphodelus dendroides Extract against Antibiotic Resistant and Biofilm Forming Klebsiella pneumoniae Clinical Strains: A Laboratory Study

Synthesis of silver nanoparticles (AgNPs) using plant extract is cost effective, while, one of the applications of AgNPs is its antimicrobial and anti-biofilm activities. The aim of this study was to investigate the anti-biofilm activity of synthesized AgNPs using A. dendroides against antibiotic resistant and biofilm forming clinical isolates of Klebsiella pneumoniae.

In this laboratory study, the AgNPs were first synthesized using Asphodelus dendroides extract and their size and structural characteristics were determined using various physico-chemical methods. Subsequently, the antimicrobial and anti-biofilm activities of synthesized AgNPs on antibiotic resistant and biofilm forming clinical isolates of K. pneumoniae were investigated via minimum inhibitory concentration (MIC) and Real Time PCR, respectively.

The results of the UV-vis test showed that the synthesized AgNPs had a maximum absorbance at 420 nm. The SEM (scanning electron microscope), TEM (transmission electron microscopy) and XRD (X-ray powder diffraction) results showed that the synthesized AgNPs had a spherical structure with a mean size of 30.41±22 nm. Also, AgNPs had significant antimicrobial and anti-biofilm activities against K. pneumoniae strains, so that the AgNPs down-regulated the expression of biofilm coding gene (mrkA) in K. pneumonia strains (p<0.001).

The results of this study showed the antimicrobial and anti-biofilm activities of AgNPs against K. pneumoniae strains. According to the results, with further studies, the synthesized AgNPs may be used as biofilm inhibitors in future.