A study on separated and combined effects of stoechas extract(Lavandula stoechas) and silver nano-particles on Klebsiella pneumoniae biofilm formation

Introduction: So-called biofilm or biomass is interacting cells or microorganisms that accumulate together as a result of various factors on a surface. Biofilm formation increases resistance to unfavorable conditions and biocides. Of the strategies to deal with biofilms is using different plant compounds and nanoparticles. The aim of this study was to determine the effect of silver nanoparticles, lavender extract, and their combined effects in different concentrations on Klebsiella pneumoniae biofilm. Materials & Methods: The anti-biofilm effect and reduced rate of biofilm formation of Klebsiella pneumoniae in separated and combined treatments of stoechas extract (Lavandula stoechas) and silver-nanoparticles at 24, 48 and 72 hours were measured by colorimetric microtiter method. Phenolic content was also measured by Folin-Ciocalteu method. Findings: Phenolic content was about 113.3 mg/g. In the absence of treatments, Klebsiella was able to form strong biofilms. Three-way-analysis of variance of the main and interacting effects of silver nanoparticles, lavender extract and time on biofilm formation was significant. Silver nanoparticle and lavander extract at concentrations of 125 and 0.0625 ug/mL, respectively, and co-treatments at 62.5 and 0.03125 ug/mL concentrations, respectively, significantely reduced biofilm formation. Discussion & Conclusions: By increasing time, biofilm formation reduced due to effects of treatments. Biofilm formation also reduced by increasing concentration of the treatments. The result of this survey showed that silver-nanoparticles and lavender extract have synergistic effects on reduction of biofilm formation