title: Antimicrobial susceptibility of photodynamic therapy (UVA/riboflavin) against Staphylococcus aureus.
abstract: OBJECTIVE
  To assess S. aureus in vitro viability after the exposure to ultraviolet light A (UVA) and riboflavin (B2).
  
  
  METHODS
  Samples of S. aureus in 96 well plates (in triplicate) were exposed to riboflavin (B2) and ultraviolet light A (365 nm wavelength) at a power density of 3 mW/cm², 8 mm spot diameter, for 30 minutes. Control groups were prepared as well in triplicate: blank control, ultraviolet light A only, riboflavin only and dead bacteria Control. The bacterial viability was measured using fluorescent microscopy. In order to investigate the occurrence of "viable but non-culturable" microorganisms after treatment, the cell viability was also investigated by plate culture procedure onto a broth medium. Statistical analysis was performed using the triplicate values from each experimental condition.
  
  
  RESULTS
  No difference was observed among the treatment group and the control samples (p=1).
  
  
  CONCLUSIONS
  The combination of riboflavin 0.1% and ultraviolet light A at 365 nm did not exhibit antimicrobial activity against oxacillin susceptible S. aureus.
authors.affiliation: Department of Ophthalmology, Escola Paulista de Medicina, Universidade Federal de São Paulo - UNIFESP, São Paulo, Brazil. renatatiemik@yahoo.com.br
authors.forename: Renata Tiemi
authors.initials: RT
authors.lastname: Kashiwabuchi
authors.forename: Yasin
authors.initials: Y
authors.lastname: Khan
authors.forename: Fabio Ramos de Souza
authors.initials: FR
authors.lastname: Carvalho
authors.forename: Flavio
authors.initials: F
authors.lastname: Hirai
authors.forename: Mauro Silveira
authors.initials: MS
authors.lastname: Campos
authors.forename: Peter John
authors.initials: PJ
authors.lastname: McDonnell
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D015169:Colony Count, Microbial; D007634:Keratitis / Q000188:drug therapy / Q000382:microbiology*; D050296:Microbial Viability; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000494:pharmacology* / Q000627:therapeutic use; D012256:Riboflavin / Q000494:pharmacology* / Q000627:therapeutic use; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014803:Vitamin B Complex / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D014803:Vitamin B Complex; D012256:Riboflavin