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

Background and Objectives: 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. Materials and Methods: 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. Results: 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). Conclusion: 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. Key words: Silver nanoparticle, Klebsiella pneumoniae, Antibacterial activity, Anti-biofilm activity, mrkA gene   Funding: This research was funded by Islamic Azad University, Central Tehran Branch. Conflict of interest: None declared. Ethical approval: The Ethical Committee of Islamic Azad University of Central Branch approved the study (IR.IAU, Tehran.REC.1397.019)   How to cite this article: Sabahi M, Hamdi S M M, Mirzaie A. Anti-biofilm Activity of Synthesized Silver Nanoparticles Using Asphodelus dendroides Extract Against Antibiotic Resistant and Biofilm Forming Klebsiella pneumoniae Clinical Strains: A Laboratory Study. J Rafsanjan Univ Med Sci 2020; 18 (12): 1233-52 [Farsi]