title: Colloidal silver: a novel treatment for Staphylococcus aureus biofilms?
abstract: BACKGROUND
  Colloidal silver is an alternative medicine consisting of silver particles suspended in water. After using this solution as a nasal spray, the symptoms of a previously recalcitrant Staphylococcus aureus (S. aureus)-infected chronic rhinosinusitis patient were observed to have improved markedly. The aim of this study was to determine whether colloidal silver has any direct bactericidal effects on these biofilms in vitro.
  
  
  METHODS
  S. aureus biofilms were grown from the ATCC 25923 reference strain on Minimum Biofilm Eradication Concentration (MBEC) device pegs, and treated with colloidal silver. Concentrations tested ranged from 10 to 150 μL colloidal silver diluted to 200 μL with sterile water in 50 μL cerebrospinal fluid (CSF) broth. Control pegs were exposed to equivalent volumes of CSF broth and sterile water. The sample size was 4 biomass values per treatment or control group. Confocal scanning laser microscopy and COMSTAT software were used to quantify biofilms 24 hours after treatment.
  
  
  RESULTS
  Significant differences from control were found for all concentrations tested bar the lowest of 10 μL colloidal silver in 200 μL. At 20 μL colloidal silver, the reduction in biomass was 98.9% (mean difference between control and treatment = -4.0317 μm(3) /μm(2) , p < 0.0001). A maximum biomass reduction of 99.8% was reached at both 100 and 150 μL colloidal silver (mean differences = -4.0681 and -4.0675μm(3) /μm(2) , respectively, p < 0.0001).
  
  
  CONCLUSIONS
  Colloidal silver directly attenuates in vitro S. aureus biofilms.
authors.affiliation: Department of Surgery-Otorhinolaryngology Head and Neck Surgery, University of Adelaide, Adelaide, SA, Australia.
authors.forename: Rachel
authors.initials: R
authors.lastname: Goggin
authors.forename: Camille
authors.initials: C
authors.lastname: Jardeleza
authors.forename: Peter-John
authors.initials: PJ
authors.lastname: Wormald
authors.forename: Sarah
authors.initials: S
authors.lastname: Vreugde
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D018533:Biomass; D002908:Chronic Disease; D003102:Colloids / Q000494:pharmacology*; D000529:Complementary Therapies; D054796:Drug Dosage Calculations; D006801:Humans; D018613:Microscopy, Confocal; D012220:Rhinitis / Q000150:complications / Q000628:therapy*; D012834:Silver / Q000494:pharmacology*; D012852:Sinusitis / Q000150:complications / Q000628:therapy*; D013203:Staphylococcal Infections / Q000150:complications / Q000628:therapy*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D003102:Colloids; D012834:Silver
keywords: CRS; S. aureus; Staphylococcus aureus; biofilms; chronic rhinosinusitis; colloidal silver