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Updated: May 13, 2026
LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation
Published on: January 24, 2025
Evidence of resistance development by Staphylococcus aureus to an in vitro, multiple stage application of 405 nm
J Stephen Guffey1, William Payne, Tyler Jones
1Department of Physical Therapy, Arkansas State University, State University, ArkaAR 72467, USA. jguffey@astate.edu
Objective:
The aim of this study was to determine whether Staphylococcus aureus could develop a resistance to 405 nm light.
Background Data:
Research indicates that certain wavelengths and treatment parameters of light promote growth of bacteria; however, our earlier work indicated that blue light effectively inactivates growth of S. aureus in vitro.
Methods:
S. aureus was tested because of its frequent isolation from skin infections and wounds. The organism was treated with 405 nm light from supraluminous diodes at a dose of 9 J/cm(2).
Results:
As anticipated, blue light produced a significant (p≤0.05) inactivation of S. aureus growth. Subsequent applications of blue light to subcultured generations of S. aureus were increasingly effective through four stages (generations). Beginning with stage five, a decrease in effectiveness (resistance) was observed.
Conclusions:
Appropriate doses of 405-nm blue light inhibit the growth of S. aureus in vitro. This research does suggest that S. aureus may be capable of developing resistance to blue light irradiation.
