New University of Porto study explores antimicrobial blue light against clinically important Candida species
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A new study from researchers at the University of Porto, published in the European Journal of Clinical Microbiology & Infectious Diseases, investigated the effectiveness of antimicrobial blue light (aBL) against four clinically important Candida species, including the multidrug-resistant Candida auris. The study was conducted using Spectral Blue's SALO device equipped with MWHI® multi-wavelength antimicrobial blue light technology, providing independent peer-reviewed evidence of the technology's antifungal activity under controlled laboratory conditions.
The researchers also examined whether repeated antimicrobial blue light exposure could lead to increased microbial tolerance, an important consideration for technologies intended for continuous use in healthcare environments.
Exploring a new approach to Candida control
Fungal infections are an increasing concern in healthcare, particularly as resistance to conventional antifungal treatments becomes more widespread. Candida auris, for example, is known for its resistance to multiple antifungal drugs and its ability to persist in hospital environments, making infection prevention and environmental hygiene especially important.
Antimicrobial blue light offers a different approach to microbial control. It works by exciting naturally occurring photosensitizers within microbial cells, such as porphyrins and flavins, generating reactive oxygen species (ROS) that damage the microorganisms.
Unlike conventional UV-C disinfection, antimicrobial blue light can be used continuously in occupied environments, providing an opportunity to complement existing cleaning and disinfection procedures.
In their 2026 study titled Antimicrobial blue light against healthcare-related Candida species: in vitro efficacy and following repeated exposure for 30 days, Fernandes and colleagues investigated the susceptibility of four Candida species to multi-wavelength antimicrobial blue light.
What did the researchers discover?
The researchers used a commercially available Spectral Blue SALO device incorporating MWHI® multi-wavelength antimicrobial blue light technology, installed inside a biosafety cabinet. By utilizing the SALO device in an independent university study, the researchers were able to evaluate the antimicrobial performance of the technology under controlled laboratory conditions against clinically relevant fungal pathogens.
All four species showed susceptibility to the treatment, although the degree of inactivation varied between species and depended on exposure duration.
The researchers also investigated whether repeated blue light exposure could affect microbial susceptibility. They exposed a reference strain of C. glabrata repeatedly over 30 days, allowing the surviving organisms to recover and grow between treatments.
Following the 30-day experiment, the researchers observed no detectable increase in tolerance to antimicrobial blue light, no changes in antifungal susceptibility and no changes in the organism's ability to form biofilms.
These findings contribute to the growing body of research exploring antimicrobial blue light as a potential tool for environmental microbial control in healthcare settings.
How did Spectral Blue MWHI® perform against the different Candida species?
Candida glabrata - Most susceptible
Both tested strains showed approximately a 99% reduction in viable organisms after 5.5–6 hours of exposure. A reference strain was also used in the 30-day repeated-exposure experiment, with no detectable increase in blue light tolerance or changes in antifungal susceptibility or biofilm formation.
Candida parapsilosis -Â Intermediate susceptibility
Both tested strains were susceptible to MWHI® treatment. The species showed the second-highest susceptibility among the four species studied.
Candida auris -Â Intermediate susceptibility
Both tested strains responded to MWHI blue light treatment. This finding is particularly relevant given Candida auris's status as an emerging multidrug-resistant pathogen and its ability to persist in healthcare environments. While antimicrobial blue light is not intended to replace established infection prevention measures, these results contribute to ongoing research into complementary approaches for environmental microbial control.
Candida albicans - Most tolerant
Both tested strains were susceptible to MWHI®, although they showed the greatest tolerance among the four species. Viable organisms remained after eight hours of exposure, demonstrating the importance of exposure duration and species-specific susceptibility.
Supporting further research into antimicrobial blue light
The study provides new evidence of the antifungal activity of multi-wavelength antimicrobial blue light against clinically important Candida species, including multidrug-resistant Candida auris. It also offers encouraging findings regarding repeated exposure, with the tested C. glabrata reference strain maintaining its susceptibility throughout the 30-day experiment.
Importantly, the findings were generated using Spectral Blue's SALO device in an independent peer-reviewed university study, adding to the growing body of scientific evidence evaluating antimicrobial blue light technologies. While further research is needed to understand performance across different environments and applications, the results support continued investigation of MWHI® technology as a complementary approach for continuous microbial reduction in healthcare and other controlled environments.
Read the full research article:
Fernandes et al. (2026), European Journal of Clinical Microbiology & Infectious Diseases.
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