Title:Harnessing the Power of Light to Treat Staphylococcal Infections Focusing on MRSA
Volume: 21
Issue: 16
Author(s): Tanupriya Agrawal, Pinar Avci, Gaurav K. Gupta, Ardeshir Rineh, Shanmugamurthy Lakshmanan, Vincent Batwala, George P Tegos and Michael R. Hamblin
Affiliation:
Keywords:
Photodynamic therapy, MRSA, PDI, blue light, UV light, photosensitizer, multi-drug efflux pump.
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.
