title: 405 nm Light exposure of osteoblasts and inactivation of bacterial isolates from arthroplasty patients: potential for new disinfection applications?
abstract: Infection rates after arthroplasty surgery are between 1-4 %, rising significantly after revision procedures. To reduce the associated costs of treating these infections, and the patients' post-operative discomfort and trauma, a new preventative method is required. High intensity narrow spectrum (HINS) 405 nm light has bactericidal effects on a wide range of medically important bacteria, and it reduced bacterial bioburden when used as an environmental disinfection method in a Medical Burns Unit. To prove its safety for use for environmental disinfection in orthopaedic theatres during surgery, cultured osteoblasts were exposed to HINS-light of intensities up to 15 mW/cm2 for 1 h (54 J/cm2). Intensities of up to 5 mW/cm2 for 1 h had no effect on cell morphology, activity of alkaline phosphatase, synthesis of collagen or osteocalcin expression, demonstrating that under these conditions this dose is the maximum safe exposure for osteoblasts; after exposure to 15 mW/cm2 all parameters of osteoblast function were significantly decreased. Viability (measured by protein content and Crystal Violet staining) of the osteoblasts was not influenced by exposure to 5 mW/cm2 for at least 2 h. At 5 mW/cm2 HINS-light is an effective bactericide. It killed 98.1 % of Staphylococcus aureus and 83.2 % Staphylococcus epidermis populations seeded on agar surfaces, and is active against both laboratory strains and clinical isolates from infected hip and knee arthroplasties. HINS-light could have potential for development as a method of disinfection to reduce transmission of bacteria during arthroplasty, with wider applications in diverse surgical procedures involving implantation of a medical device.
authors.affiliation: University of Strathclyde, Bioengineering Unit, Wolfson Centre, 06 Rottenrow, Glasgow, Strathclyde G4 0NW UK.
authors.forename: R S
authors.initials: RS
authors.lastname: McDonald
authors.forename: S
authors.initials: S
authors.lastname: Gupta
authors.forename: M
authors.initials: M
authors.lastname: Maclean
authors.forename: P
authors.initials: P
authors.lastname: Ramakrishnan
authors.forename: J G
authors.initials: JG
authors.lastname: Anderson
authors.forename: S J
authors.initials: SJ
authors.lastname: MacGregor
authors.forename: R M D
authors.initials: RM
authors.lastname: Meek
authors.forename: M H
authors.initials: MH
authors.lastname: Grant
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001178:Arthroplasty; D048430:Cell Shape / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004203:Disinfection / Q000379:methods*; D008027:Light; D050296:Microbial Viability / Q000528:radiation effects; D010006:Osteoblasts / Q000201:enzymology / Q000502:physiology / Q000528:radiation effects*; D015675:Osteocalcin / Q000378:metabolism; D051381:Rats; D013203:Staphylococcal Infections / Q000382:microbiology / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000528:radiation effects*; D013212:Staphylococcus epidermidis / Q000302:isolation & purification / Q000528:radiation effects*; D013530:Surgical Wound Infection / Q000382:microbiology / Q000517:prevention & control
chemical_list: D015675:Osteocalcin; D003094:Collagen; D000469:Alkaline Phosphatase