Colloidal silver combating pathogenic Pseudomonas aeruginosa and MRSA in chronic rhinosinusitis

Sholeh Feizi; Clare M Cooksley; George S Bouras; Clive A Prestidge; Tom Coenye; Alkis James Psaltis; Peter-John Wormald; Sarah Vreugde

doi:10.1016/j.colsurfb.2021.111675

Colloidal silver combating pathogenic Pseudomonas aeruginosa and MRSA in chronic rhinosinusitis

Colloids Surf B Biointerfaces. 2021 Jun:202:111675. doi: 10.1016/j.colsurfb.2021.111675. Epub 2021 Mar 4.

Authors

Sholeh Feizi¹, Clare M Cooksley¹, George S Bouras¹, Clive A Prestidge², Tom Coenye³, Alkis James Psaltis¹, Peter-John Wormald¹, Sarah Vreugde⁴

Affiliations

¹ Department of Surgery-Otolaryngology Head and Neck Surgery, Basil Hetzel Institute for Translational Health Research, Central Adelaide Local Health Network, Woodville South, Australia; The University of Adelaide, Adelaide, Australia.
² Clinical and Health Sciences and ARC Centre of Excellence in Convergent Bio and Nano Science and Technology, University of South Australia, Adelaide, Australia.
³ Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
⁴ Department of Surgery-Otolaryngology Head and Neck Surgery, Basil Hetzel Institute for Translational Health Research, Central Adelaide Local Health Network, Woodville South, Australia; The University of Adelaide, Adelaide, Australia. Electronic address: sarah.vreugde@adelaide.edu.au.

PMID: 33690064
DOI: 10.1016/j.colsurfb.2021.111675

Abstract

The emergence of antibiotic resistant bacteria requires for the development of new antimicrobial compounds one of which colloidal silver (CS) having strong bactericidal properties and being the most promising inorganic nanoparticles for the treatment of bacterial infectious diseases. However, their production can be slow and cumbersome. Here, we used Corymbia maculata aqueous leaf extract as a reducing agent to synthesize CS in a single 15-minute process. CS was physico-chemically characterized for shape, size, zeta potential and stability. The Minimal Inhibitory Concentration (MIC) and Minimum Biofilm Eradication Concentration (MBEC) of CS against planktonic and biofilm forms of methicillin-resistant Staphylococcus aureus (MRSA, n = 5), Pseudomonas aeruginosa (n = 5), Haemophilus influenzae (n = 5) and Streptococcus pneumoniae (n = 3) chronic rhinosinusitis clinical isolates were investigated using the microdilution method and resazurin assay, respectively. The in vitro cytotoxicity on bronchial epithelial cells (Nuli-1) was analyzed by the crystal violet proliferation assay. The safety and efficacy of CS was evaluated in an in vivo infection model in Caenorhabditis elegans. CS was spherical in shape with a diameter of between 11-16 nm (TEM analysis) in dried form and 40 nm (NanoSight) in colloidal form and was stable at room temperature and 4 °C for one year. Average MIC and MBEC values varied between 11 and 44 ppm for MRSA, H. influenzae and S. pneumoniae and between 0.2 and 3 ppm for P. aeruginosa. CS was not toxic to Nuli-1 cells or C. elegans at concentrations of 44 ppm and reduced the Colony Forming Units counts by 96.9 % and 99.6 % in C. elegans for MRSA and P. aeruginosa, respectively. In conclusion, a novel, green synthesis of stable CS is demonstrated with good safety and efficacy profiles, particularly against P. aeruginosa in planktonic and biofilm forms. These CS have potential applications against clinical infections, including in the context of CRS.

Keywords: Chronic rhinosinusitis; Eucalyptus; Green synthesis; Infection; P. aeruginosa; Silver nanoparticle.

MeSH terms

Animals
Anti-Bacterial Agents / pharmacology
Anti-Bacterial Agents / therapeutic use
Biofilms
Caenorhabditis elegans
Methicillin-Resistant Staphylococcus aureus*
Microbial Sensitivity Tests
Pseudomonas aeruginosa
Silver / pharmacology

Substances

Anti-Bacterial Agents
colloidal silver
Silver