Study of Antimicrobial activity of Ag and Se Nanoparticles against Clinically Isolated Biofilm forming Staphylococcus aureus

Abstract

Introduction- Bacterial biofilm is a group of bacterial cells, covered by self-produced polymeric matrix film, which adheres very tightly to an inert or living surface constituting a protected mode of growth, allows survival in the unfavorable environment. Silver compounds have been used to treat burns, wounds, and infections. The effect of silver nanoparticles on the cell morphology of Staphylococcus aureus has been studied using SEM microscopy. Various salts of silver and their derivatives are used as antimicrobial agents against a wide range of pathogenic microbes. Selenium is an essential trace element. Selenium in the form of nanoparticles strongly inhibits the growth of Staphylococcus aureus on polycarbonate medical devices and no negative influence showed on osteoblastic cell growth. Methodology- This study performed on thirty-six positive clinical samples of Urine, Blood and Pus. It was evaluated to phenotypic analysis test for biofilm forming Staphylococcus aureus strains by Congo red agar (CRA), Tube method (TM), and Tissue culture plate (TCP) method. Silver nanoparticles were synthesized by adopting chemical reduction, whereas Selenium nanoparticles (SeNPs) were synthesized by the reduction of sodium selenite by glutathione (reduced form). Antimicrobial activity was performed by well diffusion test of Ag and Se nanoparticles against biofilm forming Staphylococcus aureus strains. Results- Distribution pattern showed the highest isolation rate from pus 30 (83.33%) followed by blood 4 (11.11%), and urine 2 (5.56%). Among the thirty-six positive samples screened for the present study, zero identified as biofilm-forming S. aureus and Intermediate, whereas all strains 36 (100%) showed as non biofilm-forming S. aureus by Congo red agar (CRA) method. Another method for Biofilm formation were performed by Tube method, 5 (13.89%) was strongly positive and 20 (55.56%) isolates unable to not shown any biofilm production, whereas via Tissue culture plate (TCP) method showed 12 (33.33%) high biofilm-producer while 16 (44.44%) were non biofilm producer. Ag-NPs showed morphology average size and shape with scanning electron microscopy (SEM) reveals spherical particles with the size of 80.32 nm whereas, Se-NPs showed the size of 74.29 nm with scanning electron microscopy. Conclusion- For well diffusion inhibitory concentration test, 50 μl of the nanoparticles each (aqueous solution of silver and selenium) and 50 μl antibiotic (aqueous solution of amoxicillin as a positive control) were used. In this study amongst the two nanoparticles (Ag & Se) tested, silver nanoparticles were found to be the active inhibitory effects against biofilm forming Staphylococcus aureus strains (SA12, SA15, SA32), whereas selenium nanoparticles demonstrated the low inhibitory effects (SA23).