Effect of Silver Nanoparticles on Biofilm Formation and EPS Production of Multidrug-Resistant Klebsiella pneumoniae

Abstract

Antibiotic resistance against present antibiotics is rising at an alarming rate with need for discovery of advanced methods to treat infections caused by resistant pathogens. Silver nanoparticles are known to exhibit satisfactory antibacterial and antibiofilm activity against different pathogens. In the present study, the AgNPs were synthesized chemically and characterized by UV-Visible spectroscopy, scanning electron microscopy, and X-ray diffraction. Antibacterial activity against MDR K. pneumoniae strains was evaluated by agar diffusion and broth microdilution assay. Cellular protein leakage was determined by the Bradford assay. The effect of AgNPs on production on extracellular polymeric substances was evaluated. Biofilm formation was assessed by tube method qualitatively and quantitatively by the microtiter plate assay. The cytotoxic potential of AgNPs on HeLa cell lines was also determined. AgNPs exhibited an MIC of 62.5 and 125 μg/ml, while their MBC is 250 and 500 μg/ml. The production of extracellular polymeric substance decreased after AgNP treatment while cellular protein leakage increased due to higher rates of cellular membrane disruption by AgNPs. The percentage biofilm inhibition was evaluated to be 64% for K. pneumoniae strain MF953600 and 86% for MF953599 at AgNP concentration of 100 μg/ml. AgNPs were evaluated to be minimally cytotoxic and safe at concentrations of 15-120 μg/ml. The data evaluated by this study provided evidence of AgNPs being safe antibacterial and antibiofilm compounds against MDR K. pneumoniae.

All That Glitters Is Not Silver—A New Look at Microbiological and Medical Applications of Silver Nanoparticles

“…Moreover, AgNPs synthesized by Cryphonectria sp. showed antibacterial activity against various human pathogenic bacteria, including S. aureus , Klebsiella pneumoniae , E. coli , Salmonella typhi and Candida albicans [ 9 , 30 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ].…”

“…Cells included in the biofilm differ physiologically and morphologically from the free-living cells of the same species. The complex process of biofilm formation consists of several characteristic stages, such as adhesion, formation, maturation and its decay [ 77 , 78 , 79 , 80 , 81 ]. Biofilms are settled populations of one or more species of microorganisms that are attached to a biotic or abiotic solid surface or are formed at the interface [ 77 , 78 , 79 , 80 , 81 ].…”

“…Bacteria living in biofilms can easily spread in the body, leading to the chronic and difficult to cure infections. This is facilitated by the slow growth of cells and their ability to avoid host’s immune system attack [ 77 , 78 , 79 , 80 , 81 ]. Cells in biofilms are surrounded by extracellular polymeric substance, mainly composed of polysaccharides but also from proteins and nucleic acids, called a biofilm matrix.…”

“…The disturbance of their functioning by silver nanoparticles leads to changes in the virulence of these bacteria. Over 65% of all nosocomial infections come from bacterial biofilms, mainly formed by E. faecalis , S. aureus , S. epidermidis , E. coli , K. pneumoniae and P. aeruginosa [ 31 , 38 , 77 , 78 , 79 , 80 , 81 ]. The ability to create biofilms is of direct importance in the pathogenesis of cystic fibrosis, gingivitis and middle ear otitis [ 31 , 38 , 77 , 78 , 79 , 80 , 81 ].…”

Smart Nanoparticles in Biomedicine: An Overview of Recent Developments and Applications

“…Size and shape influence the antibacterial effect of silver nanoparticles: Hong et al reported a higher antibacterial effect to E. coli of silver nanocubes to spheres and wires [70]; while their antimicrobial activity decreases with increasing particles size, as reported by Raza and colleagues [48], [71]. Many studies suggest an AgNPs role in inhibiting bacterial biofilm formation and EPS (Extracellular polymeric substances) production, mainly when associated with the plant-derived drug-like quercetin [72], [73].…”