title: Photobactericidal activity of phenothiazinium dyes against methicillin-resistant strains of Staphylococcus aureus.
abstract: The photodynamic antibacterial properties of a closely related series of phenothiazinium dyes were tested against several pathogenic strains of Staphylococcus aureus, four of which were methicillin-resistant. Illumination of the photosensitisers at a fluence rate of 1.75 mW cm-2 generally resulted in the enhancement of antibacterial activity in liquid culture and in greater efficacy than the methicillin analogue flucloxacillin. For methylene blue, dimethyl methylene blue and new methylene blue illumination led to increases in bactericidal activity < or = 16-fold, typically 4-fold. In addition dimethyl methylene blue and new methylene blue were active against epidemic strains of methicillin-resistant Staphylococcus aureus at concentrations lower than that of vancomycin (> or = 0.5 microM).
authors.affiliation: Department of Chemistry, University of Central Lancashire, Preston, UK. M.Wainwright@UCLAN.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Wainwright
authors.forename: D A
authors.initials: DA
authors.lastname: Phoenix
authors.forename: S L
authors.initials: SL
authors.lastname: Laycock
authors.forename: D R
authors.initials: DR
authors.lastname: Wareing
authors.forename: P A
authors.initials: PA
authors.lastname: Wright
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001399:Azure Stains / Q000494:pharmacology; D004396:Coloring Agents / Q000494:pharmacology*; D005436:Floxacillin / Q000494:pharmacology; D006801:Humans; D008027:Light; D016106:Methicillin Resistance; D008751:Methylene Blue / Q000031:analogs & derivatives / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology; D010640:Phenothiazines / Q000494:pharmacology*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D014048:Tolonium Chloride / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001399:Azure Stains; D004396:Coloring Agents; D010406:Penicillins; D010640:Phenothiazines; D017319:Photosensitizing Agents; D014048:Tolonium Chloride; C035184:new methylene blue; D005436:Floxacillin; D014640:Vancomycin; C025819:Azure B; D008751:Methylene Blue