title: The influence of pH and fluid dynamics on the antibacterial efficacy of 45S5 Bioglass.
abstract: In recent years, there has been considerable interest in the potential antibacterial properties that bioactive glasses may possess. However, there have been several conflicting reports on the antibacterial efficacy of 45S5 Bioglass(®). Various mechanisms regarding its mode of action have been proposed, such as changes in the environmental pH, increased osmotic pressure, and 'needle-like' sharp glass debris which could potentially damage prokaryotic cell walls and thus inactivate bacteria. In this current study, a systematic investigation was undertaken on the antibacterial efficacy of 45S5 Bioglass(®) on Escherichia coli NCTC 10538 and Staphylococcus aureus ATCO 6538 under a range of clinically relevant scenarios including varying Bioglass(®) concentration, direct and indirect contact between Bioglass(®) and microorganisms, static and shaking incubation conditions, elevated and neutralised pH environments. The results demonstrated that, under elevated pH conditions, Bioglass(®) particles have no antibacterial effect on S. aureus while a concentration dependent antibacterial effect against E. coli was observed. However, the antibacterial activity ceased when the pH of the media was neutralised. The results of this current study, therefore, suggest that the mechanism of antibacterial activity of Bioglass(®) is associated with changes in the environmental pH; an environment that is less likely to occur in vivo due to buffering of the system.
authors.affiliation: School of Life & Health Science and Aston Research Centre for Healthy Ageing, University of Aston, Aston Triangle, Birmingham, B4 7ET, UK.
authors.forename: Saima
authors.initials: S
authors.lastname: Begum
authors.forename: William E
authors.initials: WE
authors.lastname: Johnson
authors.forename: Tony
authors.initials: T
authors.lastname: Worthington
authors.forename: Richard A
authors.initials: RA
authors.lastname: Martin
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry; D001422:Bacterial Adhesion / Q000187:drug effects / Q000502:physiology; D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D018786:Bone Substitutes / Q000737:chemistry / Q000494:pharmacology*; D002470:Cell Survival; D002516:Ceramics / Q000737:chemistry* / Q000494:pharmacology*; D005898:Glass / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D012212:Rheology / Q000379:methods*
chemical_list: D000900:Anti-Bacterial Agents; D018786:Bone Substitutes; C425330:bioactive glass 45S5