zithromax and vitexin

Cell Surface hydrophobicity is one of the determinant biophysical parameters of bacterial aggregation for being networked to form a biofilm. Phytoconstituent, like vitexin, has long been in use for their antibacterial effect. The present work demonstrates the role of vitexin in modulating Staphylococcus aureus surface hydrophobicity while aggregating to form biofilm and pathogenesis in a host. In planktonic form, vitexin shows minimum inhibitory concentration at 252 µg/ml against S. aureus. Sub-MIC doses of vitexin and antibiotics (26 µg/ml of vitexin, 55 µg/ml of azithromycin, and 2.5 µg/ml of gentamicin) were selected to treat S. aureus. Dead cell counts after treatment were studied through flow cytometry. As dead cell counts were minimal (<5 %), these doses were considered for all subsequent experiments. While studying aggregating cells, it was observed that vitexin reduces S. aureus surface hydrophobicity and membrane permeability at the sub-MIC dose of 26 µg/ml. The in silico binding analysis showed a higher binding affinity of vitexin with surface proteins (IcaA, DltA, and SasG) of S. aureus. Down-regulation of dltA and icaAB expression, along with the reduction in membrane potential with a sub-MIC dose of vitexin, explains reduced S. aureus surface hydrophobicity. Vitexin was found to interfere with S. aureus biofilm-associated protein biomass, EPS production, and swarming movement. Subsequently, the suppression of proteases production and down-regulation of icaAB and agrAC gene expression with a sub-MIC dose of vitexin explained the inhibition of S. aureus virulence in vitro. Besides, vitexin was also found to potentiate the antibiofilm activity of sub-MIC doses of gentamicin and azithromycin. Treatment with vitexin exhibits a protective response in S. aureus infected macrophages through modulation of expression of cytokines like IL-10 and IL-12p40 at protein and mRNA levels. Furthermore, CFU count and histological examination of infected mouse tissue (liver and spleen) justify the in vivo protective effect of vitexin from S. aureus biofilm-associated infection. From this study, it can be inferred that vitexin can reduce S. aureus surface hydrophobicity, leading to interference with aggregation at the time of biofilm formation and subsequent pathogenesis in a host.

Topics: Animals; Anti-Bacterial Agents; Apigenin; Azithromycin; Biofilms; Gentamicins; Hydrophobic and Hydrophilic Interactions; Mice; Microbial Sensitivity Tests; Staphylococcal Infections; Staphylococcus aureus

Microbial biofilm are communities of surface-adhered cells enclosed in a matrix of extracellular polymeric substances. Extensive use of antibiotics to treat biofilm associated infections has led to the emergence of multiple drug resistant strains. Pseudomonas aeruginosa is recognised as a model biofilm forming pathogenic bacterium. Vitexin, a polyphenolic group of phytochemical with antimicrobial property, has been studied for its antibiofilm potential against Pseudomonas aeruginosa in combination with azithromycin and gentamicin. Vitexin shows minimum inhibitory concentration (MIC) at 260 μg/ml. It's antibiofilm activity was evaluated by safranin staining, protein extraction, microscopy methods, quantification of EPS and in vivo models using several sub-MIC doses. Various quorum sensing (QS) mediated phenomenon such as swarming motility, azocasein degrading protease activity, pyoverdin and pyocyanin production, LasA and LasB activity of the bacteria were also evaluated. Results showed marked attenuation in biofilm formation and QS mediated phenotype of Pseudomonas aeruginosa in presence of 110 μg/ml vitexin in combination with azithromycin and gentamicin separately. Molecular docking of vitexin with QS associated LuxR, LasA, LasI and motility related proteins showed high and reasonable binding affinity respectively. The study explores the antibiofilm potential of vitexin against P. aeruginosa which can be used as a new antibiofilm agent against microbial biofilm associated pathogenesis.

Topics: Animals; Anti-Bacterial Agents; Apigenin; Azithromycin; Biofilms; Gentamicins; Mice; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Quorum Sensing