Blue light phototherapy kills methycillin resistant staphylococcus aureus (MRSA)

Chukuka S. Enwemeka, Debora Williams, Sombiri K. Enwemeka, Steve Hollosi, David Yens

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Background: Methycillin resistant staphylococcus aureus (MRSA) bacteria continue to defy most available antibiotics. As a result infections with MRSA remain a growing public health concern. As a paradigm shift and a significant departure from the on-going trend to develop stronger drug-based therapies, we studied the effect of 405nm and 470nm wavelengths of blue light on two strains of MRSA-US-300 strain of CA-MRSA and the IS853 strain of HA-MRSA-in vitro. Methods: We cultured and plated each strain, following which bacteria colonies were irradiated with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 Jcm-2 energy densities-just once. Specimens were incubated at 35°C for 24 h. Then, digital images obtained were quantified to obtain colony counts and the aggregate area occupied by bacteria colonies. Results: Each wavelength produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each bacteria strain (P < 0.001). Maximum eradication of the US-300 (92.1%) and the IS-853 colonies (93.5%) was achieved within 10 minutes of irradiation with each wavelength. The longer the irradiation the more bacteria were eradicated. However, the effect was non-linear as increases of energy densities between 1.0 and 15 J cm-2 resulted in more bacteria death than similar increases between 15 J cm-2 and 60 J cm-2. Conclusion: At low doses, blue light photo-destroys HA-MRSA and CA-MRSA in vitro; raising the prospect that phototherapy may be an effective clinical tool in the on-going effort to stem MRSA infections.

Original languageEnglish
Title of host publicationLaser Florence 2009
Subtitle of host publicationA Gallery Through the Laser Medicine World - Selected Papers at the International Laser Medicine Congress
Number of pages5
Publication statusPublished - 2010
Externally publishedYes
EventCongress of the International Academy Laser Medicine and Surgery - Firenze, Italy
Duration: 6 Nov 20097 Nov 2009

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


ConferenceCongress of the International Academy Laser Medicine and Surgery

ASJC Scopus subject areas

  • General Physics and Astronomy


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