ABSTRACT
Background: Blue light therapy (BLT) is a Food and Drug Administration cleared modality used in dermatology as an effective treatment of acne. The primary purpose of this study is to determine if there are dose-dependent antimicrobial effects of BLT against Cutibacterium acnes (C. acnes). Methods: A known strain of C. acnes was grown on chocolate agar in a controlled laboratory environment under anaerobic conditions for 1 week. After 1 week, 2-3 colonies of C. acnes were isolated and transferred to broth medium to incubate for 2 or 7 days. Broth vials (treatment arm) then underwent 1 of 6 different blue light dosing treatment regimens and a duplicate broth vial served as a control left open to the same environment. The BLT regimens were a single treatment of 25 J/cm2, 50 J/cm2, 75 J/cm2, 100 J/cm2, 2 serial treatments of 50 J/cm2 separated by 24 hours, or 2 serial treatments of 75 J/cm2 separated by 24 hours. The Omnilux Blue device (415 nm wavelength) was used for all BLT treatments and delivered, on average, 1.68 ± 0.004 J/min. Following treatment, the control and treatment broth samples were plated on chocolate agar and allowed to grow for 7 days. After 7 days, plates were counted and colony forming units (CFUs) were calculated. Six trials were completed for each BLT dosing regimen based on an a priori power analysis of 6 individual 2-sided t-tests. Comparisons in the primary outcome were made via mixed-effects analysis of variance with replicate as a random effect. Results: All BLT treatment regimens resulted in significantly fewer CFUs than their aggregate control plate CFUs (P < .05 for all). Furthermore, in 2-way comparison of CFUs between BLT treatment groups, a single treatment of 75 J/cm2 did lead to significantly less growth than 25 J/cm2 (P = .017) and 50 J/cm2 (P = .017). There were no improved antimicrobial effects with serial treatments when comparing 2 doses of 50 J/cm2 with a single dose of 100J/cm2, nor were 2 doses of 75 J/cm2 more efficacious than 100 J/cm2. Using the Omnilux Blue device, it took 44.8 minutes to deliver a 75 J/cm2 dose. Conclusion: BLT is an effective antimicrobial agent against this single virulent strain of C. acnes. Treatment dosing of 75 J/cm2 was identified to be the most effective dose per unit time. Serial treatments did not lead to superior antimicrobial effects over a single, high-dose treatment.
ABSTRACT
BACKGROUND: The purpose of this study was to compare the efficacy of blue light therapy (BLT) and 5% topical benzoyl peroxide (BPO) gel in combination with standard chlorhexidine (CHX) preparation in eradicating Cutibacterium acnes at the deltopectoral interval measured by positive, quantitative culture findings. METHODS: Adult male volunteers were randomized to 1 of 3 treatment groups: BPO, BLT, and BPO followed by BLT. Contralateral shoulders served as matched controls. Volunteers randomized to BPO applied the gel for a total of 5 treatments. In the BLT group, a single 23-minute treatment was administered at an estimated irradiance of 40 mW/cm2 (radiant exposure, 55.2 J/cm2). In the BPO-BLT group, volunteers received both treatments as described earlier. After treatment with either BPO, BLT, or both, a single swab culture was taken from the treatment shoulder. Next, control and treatment shoulders were prepared with CHX, and cultures were taken from each shoulder. Cultures were sent for anaerobic quantitative growth analysis with both polymerase chain reaction and Sanger sequencing confirmation of presumptive C acnes colonies. RESULTS: This study enrolled 60 male volunteers, 20 per group, with no loss to follow-up. After treatment but prior to CHX administration, all culture samples in the BPO group and BLT group grew C acnes. Prior to CHX, 16 samples (80%) in the BPO-BLT group grew C acnes. On quantitative analysis, the BPO group and BPO-BLT group had significantly less growth of C acnes compared with the BLT group after treatment but prior to CHX (P < .05 for each). Following CHX administration, the BPO and BPO-BLT groups had significantly fewer positive culture findings (odds ratios of 0.03 and 0.29, respectively) and less quantity of growth compared with their control arms (P < .05). This was not seen in the BLT group. For quantitative between-group analysis, no significant synergistic effects were seen with BPO-BLT compared with BPO alone (P = .688). There was no difference in side effects between groups. CONCLUSION: The combination of topical BPO and CHX was effective at eliminating C acnes in most cases. BLT alone did not demonstrate effective antimicrobial properties against C acnes at the radiant exposure administered in this study. Combining BPO and BLT did not lead to significant synergistic antimicrobial effects. Both BPO and BLT are safe with few, transient side effects reported. More work is needed to determine whether BLT at higher radiant exposures or serial treatment results in bactericidal effects against C acnes in vivo.
Subject(s)
Dermatologic Agents , Shoulder Joint , Adult , Benzoyl Peroxide , Chlorhexidine , Humans , Male , Propionibacterium acnes , SkinABSTRACT
Anagen effluvium (AE) is a type of alopecia with hair loss during the growth phase of a hair follicle and is most often associated with cytotoxic chemotherapy. This report describes a case of AE in a critically ill 2-year-old boy who developed cardiorespiratory failure requiring extracorporeal membranous oxygenation. We postulate that the combination of hypotension and hypoxia with subsequent reperfusion triggered an apoptotic cascade in the hair matrix, resulting in AE.
