Photobiomodulation with LED does not alter antibiotic sensitivity in ATCC and burn-patient bacteria

The association of photobiomodulation (PBM) and antibiotics has been little investigated for bacterial control.

This study aimed to verify possible changes in the antibiotic sensitivity profile in ATCC-type bacteria and bacteria collected from burned patients after irradiation with 465 and 630 nm LED at 30, 40 and 50 J/cm².

The species Staphylococcus aureus (ATCC^®BAA-977), Pseudomonas aeruginosa (ATCC 27853), and Staphylococcus aureus and Pseudomonas aeruginosa from burned patients were used as proof of concept. A qualitative method was adopted to verify the antibiotic sensitivity profile. To quantify oxidative stress, assessments were performed using Malondialdehyde (MDA) and antioxidant action using glutathione (GSH). Data were analyzed by Shapiro-Wilk and ANOVA single-factor tests, with Tukey post-hoc (p < 0.05).

Differences between the irradiated groups were found, however, without statistical significance or representing a change in the sensitivity profile of the bacteria investigated. The highest production of oxidative stress was at 465 nm (30 J/cm²), and no glutathione production was detected.

LED irradiation was found to be safe for application to bacterial colonies, as it did not modify their antibiotic susceptibility profile, despite inducing oxidative stress.