title: Effects of toluidine blue O (TBO)-photodynamic inactivation on community-associated methicillin-resistant Staphylococcus aureus isolates.
abstract: OBJECTIVE
  Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized as a leading pathogen and has been shown to be genetically different from the health care-associated MRSA (HA-MRSA). Photodynamic therapy (PDT) is considered a potential alternative method for the treatment of resistant bacterial infections, but the effect of PDT on CA-MRSA is unknown. The purpose of this study was to compare the bactericidal effects of toluidine blue O (TBO) on CA-MRSA and HA-MRSA and investigate the photodynamic inactivation effects of TBO (TBO-PDI) against bacterial virulence factors.
  
  
  METHODS
  TBO-PDI effects were determined by measuring the survival fractions for four strains and bactericidal activities for 26 CA-MRSA isolates and 26 HA-MRSA isolates. The influences of TBO-PDI on DNA fragmentation and the activities of protease, lipase, staphylococcal α-hemolysin, and enterotoxin were studied.
  
  
  RESULTS
  TBO-PDI has effective bactericidal activity against both CA- and HA-MRSA. However, the bactericidal activity of TBO-PDI was significantly higher against HA-MRSA than CA-MRSA isolates. In addition, TBO-PDI treatment using a sublethal TBO concentration led to reduced production of several virulence factors, including protease, lipase, staphylococcal α-hemolysin, and enterotoxin.
  
  
  CONCLUSIONS
  Although TBO-PDI is slightly less effective against CA-MRSA than HA-MRSA isolates, TBO-PDI could reduce the production of virulence factors at a sublethal TBO concentration, which would be beneficial for treating CA-MRSA infections.
authors: Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors: Sung-Pin
authors: SP
authors: Tseng
authors: Department of Microbiology and Immunology, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors: Wei-Chun
authors: WC
authors: Hung
authors: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Hsiao-Jan
authors: HJ
authors: Chen
authors: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Yu-Tzu
authors: YT
authors: Lin
authors: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Hung-Sih
authors: HS
authors: Jiang
authors: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Hao-Chieh
authors: HC
authors: Chiu
authors: Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan; Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors: Po-Ren
authors: PR
authors: Hsueh
authors: Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors: Lee-Jene
authors: LJ
authors: Teng
authors: Center for Optoelectronic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Surgery, Division of Neurosurgery, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: jctsai@ntu.edu.tw.
authors: Jui-Chang
authors: JC
authors: Tsai
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017714:Community-Acquired Infections / Q000382:microbiology*; D003428:Cross Infection / Q000382:microbiology; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D050296:Microbial Viability / Q000187:drug effects; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology*; D014048:Tolonium Chloride / Q000494:pharmacology*; D037521:Virulence Factors / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D037521:Virulence Factors; D014048:Tolonium Chloride
keywords: CA-MRSA; photodynamic inactivation; virulence factors