title: Harnessing the power of light to treat staphylococcal infections focusing on MRSA.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) has become the most important drug-resistant microbial pathogen in countries throughout the world. Morbidity and mortality due to MRSA infections continue to increase despite efforts to improve infection control measures and to develop new antibiotics. Therefore alternative antimicrobial strategies that do not give rise to development of resistance are urgently required. A group of therapeutic interventions has been developed in the field of photomedicine with the common theme that they rely on electromagnetic radiation with wavelengths between 200 and 1000 nm broadly called "light". These techniques all use simple absorption of photons by specific chromophores to deliver the killing blow to microbial cells while leaving the surrounding host mammalian cells relatively unharmed. Photodynamic inactivation uses dyes called photosensitizers (PS) that bind specifically to MRSA cells and not host cells, and generate reactive oxygen species including singlet oxygen and singlet oxygen upon illumination. Sophisticated molecular strategies to target the PS to MRSA cells have been designed. Ultraviolet C radiation can damage microbial DNA without unduly harming host DNA. Blue light can excite endogenous porphyrins and flavins in MRSA cells that are not present in host cells. Near-infrared lasers can interfere with microbial membrane potentials without raising the temperature of the tissue. Taken together these innovative approaches towards harnessing the power of light suggest that the ongoing threat of MRSA may eventually be defeated.
authors.forename: Tanupriya
authors.initials: T
authors.lastname: Agrawal
authors.forename: Pinar
authors.initials: P
authors.lastname: Avci
authors.forename: Gaurav K
authors.initials: GK
authors.lastname: Gupta
authors.forename: Ardeshir
authors.initials: A
authors.lastname: Rineh
authors.forename: Shanmugamurthy
authors.initials: S
authors.lastname: Lakshmanan
authors.forename: Vincent
authors.initials: V
authors.lastname: Batwala
authors.forename: George P
authors.initials: GP
authors.lastname: Tegos
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114. hamblin@helix.mgh.harvard.edu.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hamblin
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D053685:Laser Therapy / Q000379:methods; D008027:Light; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects; D016896:Treatment Outcome; D014467:Ultraviolet Therapy / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species