Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light

Killing bacterial spores with blue light: when innate resistance meets the power of light

This article is a highlight of the study by Maclean et al. in this issue of Photochemistry and Photobiology describing the sporicidal effects 405 nm visible light alone on endospores of the Clostridium and Bacillus genera. 1.73 kJ cm(-2) was capable of reducing endospore colony-forming units by up to 4-log(10). These findings have never been previously demonstrated and may be incorporated into decontamination methods that span medical, military and food preparatory applications.

Acne vulgarism treatment using ultra-short laser pulse generated by micro- and nano-ring resonator system

Acne vulgaris is adebilitating dermatologic disease, and is conventionally treated by laser therapy using a microring resonator system. An evolving understanding of laser-tissue interactions involving Propioni bacterium acneproducing porphyrins, and the development of lasers to target the sebaceous glands, has led to the development of an escalating number of laser light for acne treatment. The results show that the full width at half maximum of the proposed laser pulse of 0.15 nm can be generated using a microring resonator system. The power of the laser is 200 W and the wavelength laser is 1,032 nm, which is proposed as a treatment of acne vulgaris diseases.

Sporicidal effects of high-intensity 405 nm visible light on endospore-forming bacteria

Resistance of bacterial endospores to treatments, including biocides, heat and radiation is a persistent problem. This study investigates the susceptibility of Bacillus and Clostridium endospores to 405 nm visible light, wavelengths which have been shown to induce inactivation of vegetative bacterial cells. Suspensions of B. cereus endospores were exposed to high-intensity 405 nm light generated from a light-emitting diode array and results demonstrate the induction of a sporicidal effect. Up to a 4-log(10) CFU mL(-1) reduction in spore population was achieved after exposure to a dose of 1.73 kJ cm(-2). Similar inactivation kinetics were demonstrated with B. subtilis, B. megaterium and C. difficile endospores. The doses required for inactivation of endospores were significantly higher than those required for inactivation of B. cereus and C. difficile vegetative cells, where ca 4-log(10) CFU mL(-1) reductions were achieved after exposure to doses of 108 and 48 J cm(-2), respectively. The significant increase in dose required for inactivation of endospores compared with vegetative cells is unsurprising due to the notorious resilience of these microbial structures. However, the demonstration that visible light of 405 nm can induce a bactericidal effect against endospores is significant, and could have potential for incorporation into decontamination methods for the removal of bacterial contamination including endospores.

Inhibitory effects of 405 nm irradiation on Chlamydia trachomatis growth and characterization of the ensuing inflammatory response in HeLa cells

Background

Chlamydia trachomatis is an intracellular bacterium that resides in the conjunctival and reproductive tract mucosae and is responsible for an array of acute and chronic diseases. A percentage of these infections persist even after use of antibiotics, suggesting the need for alternative treatments. Previous studies have demonstrated anti-bacterial effects using different wavelengths of visible light at varying energy densities, though only against extracellular bacteria. We investigated the effects of visible light (405 and 670 nm) irradiation via light emitting diode (LEDs) on chlamydial growth in endocervical epithelial cells, HeLa, during active and penicillin-induced persistent infections. Furthermore, we analyzed the effect of this photo treatment on the ensuing secretion of IL-6 and CCL2, two pro-inflammatory cytokines that have previously been identified as immunopathologic components associated with trichiasis in vivo.

Results

C. trachomatis-infected HeLa cells were treated with 405 or 670 nm irradiation at varying energy densities (0 – 20 J/cm²). Bacterial growth was assessed by quantitative real-time PCR analyzing the 16S: GAPDH ratio, while cell-free supernatants were examined for IL-6 and monocyte chemoattractant protein-1 (CCL2) production. Our results demonstrated a significant dose-dependent inhibitory effect on chlamydial growth during both active and persistent infections following 405 nm irradiation. Diminished bacterial load corresponded to lower IL-6 concentrations, but was not related to CCL2 levels. In vitro modeling of a persistent C. trachomatis infection induced by penicillin demonstrated significantly elevated IL-6 levels compared to C. trachomatis infection alone, though 405 nm irradiation had a minimal effect on this production.

Conclusion

Together these results identify novel inhibitory effects of 405 nm violet light on the bacterial growth of intracellular bacterium C. trachomatis in vitro, which also coincides with diminished levels of the pro-inflammatory cytokine IL-6.

Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond?

Blue light, particularly in the wavelength range of 405-470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that blue light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another light-based antimicrobial approach being investigated. In this review, we discussed the blue light sensing systems in microbial cells, antimicrobial efficacy of blue light, the mechanism of antimicrobial effect of blue light, the effects of blue light on mammalian cells, and the effects of blue light on wound healing. It has been reported that blue light can regulate multi-cellular behavior involving cell-to-cell communication via blue light receptors in bacteria, and inhibit biofilm formation and subsequently potentiate light inactivation. At higher radiant exposures, blue light exhibits a broad-spectrum antimicrobial effect against both Gram-positive and Gram-negative bacteria. Blue light therapy is a clinically accepted approach for Propionibacterium acnes infections. Clinical trials have also been conducted to investigate the use of blue light for Helicobacter pylori stomach infections and have shown promising results. Studies on blue light inactivation of important wound pathogenic bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa have also been reported. The mechanism of blue light inactivation of P. acnes, H. pylori, and some oral bacteria is proved to be the photo-excitation of intracellular porphyrins and the subsequent production of cytotoxic reactive oxygen species. Although it may be the case that the mechanism of blue light inactivation of wound pathogens (e.g., S. aureus, P. aeruginosa) is the same as that of P. acnes, this hypothesis has not been rigorously tested. Limited and discordant results have been reported regarding the effects of blue light on mammalian cells and wound healing. Under certain wavelengths and radiant exposures, blue light may cause cell dysfunction by the photo-excitation of blue light sensitizing chromophores, including flavins and cytochromes, within mitochondria or/and peroxisomes. Further studies should be performed to optimize the optical parameters (e.g., wavelength, radiant exposure) to ensure effective and safe blue light therapies for infectious disease. In addition, studies are also needed to verify the lack of development of microbial resistance to blue light.

Prospects for a novel ultrashort pulsed laser technology for pathogen inactivation

The threat of emerging pathogens and microbial drug resistance has spurred tremendous efforts to develop new and more effective antimicrobial strategies. Recently, a novel ultrashort pulsed (USP) laser technology has been developed that enables efficient and chemical-free inactivation of a wide spectrum of viral and bacterial pathogens. Such a technology circumvents the need to introduce potentially toxic chemicals and could permit safe and environmentally friendly pathogen reduction, with a multitude of possible applications including the sterilization of pharmaceuticals and blood products, and the generation of attenuated or inactivated vaccines.

The antifungal effect of light emitting diode on Malassezia yeasts

BACKGROUND

Malassezia (M.) species are members of the normal part of the skin flora, but they might induce or be involved with various cutaneous diseases. Although the role of Malassezia in the pathogenesis of cutaneous diseases is not fully understood, recent studies have shown that decreased density of Malassezia led to improvement of these diseases.

OBJECTIVE

To identify the antifungal effect of light emitting diode (LED) against Malassezia, its antifungal mechanisms and the impact on the keratinocytes.

METHODS

LED with various wavelengths (370-630nm) on Malassezia furfur, Malassezia sympodialis and Malassezia globosa was irradiated according to dose and then the antifungal effects were thereafter assessed. After irradiating LED with 392.5±1nm of wavelength according to dose on Malassezia species, reactive oxygen species (ROS) and lipid hydroperoxide production assay were measured. In addition, cell viability and inflammatory cytokines (IL-1α, IL-1β, TNF-α, TGF-β, TLR-2 and COX-2) expressions in normal human epidermal keratinocytes (NHEKs) by LED irradiation were evaluated.

RESULTS

The growth of Malassezia species was dose-dependently suppressed by both LED with 380±2 and 392.5±1nm wavelengths. The increases of intracellular and extracellular ROS by LED irradiation with 392.5±1nm wavelengths were significantly observed compared to control group. The cell viability and cytokines in NHEKs were not significantly affected by LED irradiation under 5J/cm(2)in vitro.

CONCLUSION

LED irradiation with 380±2 and 392.5±1nm wavelengths proved to have antifungal effect against Malassezia species and no impact on NHEKs under 5J/cm(2). The findings suggest that LED might be an adjunctive therapeutic light tool against Malassezia yeasts related cutaneous diseases.

Bactericidal effects of 405 nm light exposure demonstrated by inactivation of Escherichia, Salmonella, Shigella, Listeria, and Mycobacterium species in liquid suspensions and on exposed surfaces

The bactericidal effect of 405 nm light was investigated on taxonomically diverse bacterial pathogens from the genera Salmonella, Shigella, Escherichia, Listeria, and Mycobacterium. High-intensity 405 nm light, generated from an array of 405-nm light-emitting diodes (LEDs), was used to inactivate bacteria in liquid suspension and on exposed surfaces. L. monocytogenes was most readily inactivated in suspension, whereas S. enterica was most resistant. In surface exposure tests, L. monocytogenes was more susceptible than Gram-negative enteric bacteria to 405 nm light when exposed on an agar surface but interestingly less susceptible than S. enterica after drying onto PVC and acrylic surfaces. The study findings, that 405 nm light inactivates diverse types of bacteria in liquids and on surfaces, in addition to the safety advantages of this visible (non-UV wavelength) light, indicate the potential of this technology for a range of decontamination applications.

Clinical efficacy of home-use blue-light therapy for mild-to moderate acne

INTRODUCTION

Blue-light light-emitting diode (LED) therapy has become widely used for the treatment of inflammatory acne. In this study we evaluated the efficacy of a home use blue-light LED application in improving lesions and shortening their time to clearance.

METHODS

This was an IRB approved randomized self-control study. For each patient (n = 30), 2 similar lesions, one of each side of the face were chosen for treatment with either a blue-light LED hand-held or sham device. Treatments (n = 4) were conducted twice daily in the clinic and lesions were followed-up till resolution. Reduction in blemishes size and erythema and the overall improvement were evaluated by both the physician and the patients. Time to lesion resolution was recorded.

RESULTS

There was a significant difference in the response of lesions to the blue-light LED application as opposed to the placebo in terms of reduction in lesion size and lesion erythema as well as the improvement in the overall skin condition (p < 0.025). Signs of improvement were observed as early as post 2 treatments. Time to resolution was significantly shorter for the blue-light LED therapy.

CONCLUSION

The results support the effectiveness of using blue-light LED therapy on a daily basis for better improvement and faster resolution of inflammatory acne lesions.

Effects of 420-nm intense pulsed light in an acne animal model

BACKGROUND

Blue light in the 400-420 nm range has been shown to reduce the levels of Propionibacterium acnes (P. acnes) in the skin. P. acnes has been postulated to be a critical trigger for inflammatory acne. Thus, treatment with 420 nm-intense pulsed light should reduce inflammatory activity in acne.

AIM

To evaluate the clinical and histological effects of 420 nm-intense pulsed light treatment on acne in animal model.

METHOD

Inflammation acne animal model was constructed by intradermal injection of P. acnes of rat auricular. Levels of tumour necrosis factor alpha (TNF-α) and matrix metalloproteinase 2 (MMP-2), markers of inflammation implicated in acne, were assessed in treated and untreated animals by immunohistochemistry and quantitative polymerase chain reaction (PCR).

RESULT

Treatment with 420 nm intense pulsed light led to marked improvement after 6 biweekly treatments. Immunohistochemistry and PCR showed that TNF-α and MMP-2 levels correlated with the extent of acneiform activity and were reduced by treatment with 420 nm light.

CONCLUSION

A 420-nm intense pulsed light may exert its beneficial effects on inflammatory acne by reducing the levels of P. acnes and secondarily reducing inflammation induced by the bacteria.

[Physico-biological foundation of skin fluorescence--review]

Fluorescence is a peculiar aspect of photoluminescence. Some intrinsic components of the skin are fluorophores. Other synthetic components are metabolized into fluorophores. These characteristics may be used for identifying some specific aspects of skin physiopathology. Recent technological evolution has provided new devices bringing sensitive and specific information from the skin. This review presents a synthesis of the progress made in the field of fluorescence and specular reflexion of incident UV light on the skin.

Enhancement of cutaneous immune response to bacterial infection after low-level light therapy with 1072 nm infrared light: a preliminary study

We investigated the photobiomodulation effects of 1072 nm infrared light on the natural immune response involved in anti-bacterial and wound healing processes. Thirty mice infected with MRSA on the skin were divided into two groups. The experimental group was treated with 1072 nm infrared light (irradiance: 20 mW/cm(2), fluence: 12 J/cm(2) for 10 min) at 2, 4, 8, 12, 24 h, 3 and 5 days after inoculation and the control group with sham light. Serial changes of the mRNA levels of TLR2, IL-1β, TNF-α, IL-6, iNOS, MCP-1, TGF-β, bFGF and VEGF were studied by real time RT-PCR and those of the expression level of VEGF, bFGF, TGF-β and NF-κB by immunohistochemistry. The mRNA levels of the cytokines involved in the early phase of anti-bacterial immune response (IL-1β, TNF-α, IL-6, MCP-1) increased significantly in the 1072 nm group, peaking between 12 and 24 h post-inoculation. These levels normalized after 3-5 days. Immunohistochemistry revealed a notably stronger expression of VEGF in the 1072 nm group from 8-h post-inoculation to 5-day post-inoculation. We concluded that 1072 nm infrared light had a photobiomodulation effect which resulted in an enhanced biological immune response to the bacterial infection by MRSA and also increased the expression of VEGF to a significant level.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Laser treatment of acne vulgaris

Traditional medical treatments for acne vulgaris include a variety of topical and oral medications. The combination of poor compliance, lack of durable remission, and potential side effects are common drawbacks to these treatments. The use of lasers and light devices has increased dramatically in recent years due to the overall ease of treatment, predictable clinical efficacy, and minimal adverse effects. A variety of light and laser devices has been used for the treatment of acne, including the potassium titanyl phosphate (KTP) laser, the 585- and 595-nm pulsed dye lasers, the 1450-nm diode laser, radiofrequency devices, intense pulsed light sources, low-intensity light treatment, and photodynamic therapy using 5-aminolevulinic acid and indocyanine green. These devices are thought to target underlying pathogenic factors such as Propionibacterium acnes colonization, increased sebaceous gland activity, and the cutaneous inflammatory response. Lasers in particular also have a central role in the management of acne scarring, which tends to be refractory to medical therapies. Fractional photothermolysis, the 1450-nm diode laser, and pulsed dye lasers have been used in the nonablative treatment of acne scars with significant success. In this article, we review the current status of light- and laser-based treatment of acne and related conditions and briefly review the use of lasers for the treatment of acne scarring.

Studies of inactivation of encephalomyocarditis virus, M13 bacteriophage, and Salmonella typhimurium by using a visible femtosecond laser: insight into the possible inactivation mechanisms

We report experimental results on the inactivation of encephalomyocarditis virus, M13 bacteriophage, and Salmonella typhimurium by a visible femtosecond laser. Our results suggest that inactivation of virus and bacterium by a visible femtosecond laser involves completely different mechanisms. Inactivation of viruses by a visible femtosecond laser involves the breaking of hydrogen∕hydrophobic bonds or the separation of the weak protein links in the protein shell of a viral particle. In contrast, inactivation of bacteria is related to the damage of their DNAs due to irradiation of a visible femtosecond laser. Possible mechanisms for the inactivation of viruses and bacteria are discussed.

The use of photosensitisers in acne treatment

Whereas the standard approach to the treatment of acne vulgaris has involved both systemic and topical antibiotics and topical agents such as benzoyl peroxide, problems exist due to side effects, drug resistance and lack of compliance. The photoantimicrobial approach offers a rapid treatment for large areas of afflicted dermis, based on the generation of reactive oxygen species in situ. Various chemical types are available as a topical modality, both in respect of the photosensitising agent and the activating light source, the suggested therapeutic approach requiring medical supervision. Due to a novel mode of action, the use of photosensitisers constitutes a convenient option against drug-resistant bacteria.

Effect of 405-nm high-intensity narrow-spectrum light on fibroblast-populated collagen lattices: an in vitro model of wound healing

High-intensity narrow-spectrum (HINS) 405-nm light is a novel technology developed to address the significant problem of health-care associated infection. Its potential for wound-decontamination applications is assessed on mammalian cells and bacteria. The fibroblast-populated collagen lattice (FPCL) is used as an in vitro model of wound healing, and the effect of HINS light on contraction is examined. Effects on cell proliferation, morphological changes, and α-smooth muscle actin (α-SMA) expression are investigated. Bactericidal effects are assessed using the bacterium Staphylococcus epidermidis. Low doses of HINS light were found to have no significant inhibitory effects on FPCL contraction, cell proliferation, or α-SMA expression. Doses of up to 18 Jcm(-2) had no significant inhibitory effects on FPCL cell numbers, and this dose was shown to cause almost complete inactivation of bacteria. These results show that HINS light has potential for disinfection applications without adversely influencing wound healing.

Exogenous coproporphyrin III production by Corynebacterium aurimucosum and Microbacterium oxydans in erythrasma lesions

Erythrasma is a superficial skin disease caused by Gram-positive Corynebacterium species. Coral-red fluorescence under Wood's light, strongly suggestive of erythrasma, can be attributed to the presence of porphyrins. Fractionated porphyrin analysis in erythrasma lesions is yet to be reported. We attempted to investigate erythrasma lesions by isolating the responsible bacteria and determining their exogenous porphyrin production by HPLC analysis. We observed a 78-year-old woman with erythrasma who had a well-demarcated slightly scaling patch on her left foot, between the fourth and fifth toes. Two kinds of colonies on 5 % sheep blood agar were obtained from this lesion. Analysis of the 16S rRNA sequence revealed the colonies to be Corynebacterium aurimucosum and Microbacterium oxydans. HPLC analysis demonstrated that coproporphyrin III (Copro III) levels were clearly elevated, although the amounts of protoporphyrin were diminished. These results indicate that the fluorescent substance was Copro III. This study supports the view that excess Copro III synthesis by C. aurimucosum and M. oxydans leads to accumulation of porphyrin in cutaneous tissue, which emits a coral-red fluorescence when exposed to Wood's light.

Topical ALA-Photodynamic Therapy for Acne Can Induce Apoptosis of Sebocytes and Down-regulate Their TLR-2 and TLR-4 Expression

BACKGROUND

Although photodynamic therapy (PDT) is widely performed for acne, little is known about its exact therapeutic mechanism.

OBJECTIVE

We aimed to estimate the efficacy and safety of PDT on acne and to discover its mode of action.

METHODS

We performed PDT on 12 patients with mild to moderate acne. The clinical efficacy was assessed by counting the acne lesions and measuring the sebum secretion before and after PDT. In addition, we took biopsy samples from the peri-lesional areas before and after 3-session of PDT. To examine the degree of apoptosis of the sebaceous follicles, TUNEL assay was performed. To investigate the changes of toll-like receptor (TLR)-2 and TLR-4 expression after PDT, immunohistochemical stainings were also carried out. Finally, we performed TUNEL assay using the cultured sebocytes to confirm the apoptosis of sebocytes in vitro after PDT.

RESULTS

There was a significant reduction in the number of inflammatory acne lesions after PDT, compared to baseline (p<0.05). Sebum excretion significantly decreased 2 weeks after the first PDT session except for one patient (p<0.05). The TUNEL positive cells in the peri-lesional sebaceous glands after PDT markedly increased, compared with those of before PDT. A decrease in TLR-2 and TLR-4 expression by sebaceous glands and epidermis after PDT was 50% and 30%, respectively.

CONCLUSION

Our results demonstrate that apoptosis of the sebaceous glands is associated with improvement of acne by PDT. PDT has shown to down-regulate TLR-2 and TLR-4 expression in the sebaceous glands and epidermis of acne patients.

New approaches in light/laser therapies and photodynamic treatment of acne

Acne is a domain in which the technology and understanding of light/laser therapeutic procedures have advanced considerably. The aim of the paper was to revisit adjunctive physical treatments of acne, including light/laser treatments and photodynamic therapy. This review summarizes findings about such treatment modalities with particular emphasis on efficacy and safety. A number of laser/light-based modalities have been developed to meet the increasing demand for new acne treatments. The current devices correspond, on the one hand, to light-emitting diode therapy and, on the other hand, to the 532-nm potassium titanyl phosphate laser, the 585- and 595-nm pulsed dye laser, the 1450-nm diode laser, the 1320-nm Nd:YAG laser and intense pulsed light. Photodynamic therapy is also available. It is claimed that light/laser treatments might induce a faster response compared with the 1-3 months needed for response to traditional oral and topical treatments. In conclusion, pulsed dye laser shows efficacy in some patients with mild to moderate acne. The relative effectiveness compared with other treatments is unconfirmed; from the published information, evidence-based efficacy assessment of light/laser therapies in acne remains almost impossible.

Comparative study of the bactericidal effects of 5-aminolevulinic acid with blue and red light on Propionibacterium acnes

Propionibacterium acnes naturally produces endogenous porphyrins that are composed of coproporphyrin III (CPIII) and protoporphyrin IX (PpIX). Red light alone and photodynamic therapy (PDT) improve acne vulgaris clinically, but there remains a paucity of quantitative data that directly examine the bactericidal effects that result from PDT on P. acnes itself in vitro. The purpose of this study was to measure the difference of bactericidal effects of 5-aminolevulinic acid (ALA)-PDT with red and blue light on P. acnes. P. acnes were cultured under anaerobic conditions and divided into two groups (ALA-treated group and control group), and were then illuminated with blue (415 nm) and red (635 nm) lights using a light-emitting diode (LED). The cultured P. acnes were killed with both blue and red LED light illumination. The efficacy increased with larger doses of light and a greater number of consecutive illuminations. We demonstrated that red light phototherapy was less effective for the eradication of P. acnes than blue light phototherapy without the addition of ALA. However, pretreatment with ALA could enhance markedly the efficacy of red light phototherapy.

Photodynamic antimicrobial chemotherapy by liposome-encapsulated water-soluble photosensitizers

Photodynamic antimicrobial chemotherapy is an alternative method for killing bacterial cells in view of the increasing problem of multi-antibiotic resistance. We examined the effect of three water-soluble photosensitizers (PhS): methylene blue (MB), neutral red (NR) and rose bengal (RB) on Gram-positive and Gram-negative bacteria. We compared the efficacy of PhS in their free form and encapsulated in liposomal formulations against various bacterial strains, and determined conditions for the effective use of encapsulated PhS. We found that all three PhS were able to eradicate the Gram-positive microbes Staphylococcus aureus and Sarcina lutea; and MB and RB were effective against St. epidermidis. In the case of the Gram-negative species, MB and RB were cytotoxic against the Shigella flexneri, NR-inactivated Escherichia coli and Salmonella para B, and BR was effective in killing Pseudomonas aeruginosa. None of the examined PhS showed activity against Klebsiella pneumoniae. MB and NR enclosed in liposomes gave a stronger antimicrobial effect than free PhS for all tested prokaryotes, whereas encapsulation of RB led to no increase in its activity. We suggest that encapsulation of PhS can increase the photoinactivation of bacteria.

Photodynamic therapy for acne vulgaris: a randomized, controlled, split-face clinical trial of topical aminolevulinic acid and pulsed dye laser therapy

BACKGROUND

There remains the need for more effective therapeutic options to treat acne vulgaris. Interest in light-based acne treatments has increased, but few randomized, controlled clinical trials assessing the value of photodynamic therapy (PDT) for acne have been reported.

AIMS

We sought to examine the efficacy of PDT using 5-aminolevulinic acid (ALA) and pulsed dye laser therapy in the treatment of acne.

PATIENTS/METHODS

We conducted a randomized, controlled, split-face, single-blind clinical trial of 44 patients with facial acne. Patients were randomized to receive three pulsed dye laser treatments to one side of the face after a 60-90 min ALA application time, while the contralateral side remained untreated and served as a control. Serial blinded lesion counts and global acne severity ratings were performed.

RESULTS

Global acne severity ratings improved bilaterally with the improvement noted to be statistically significantly greater in treated skin than in untreated skin. Erythematous macules (remnants of previously active inflammatory lesions) decreased in number in treated skin when compared with control skin and there was a transient but significant decrease in inflammatory papules in treated skin when compared with untreated skin. There were no other statistically significant differences between treated and untreated sides of the face in terms of counts of any subtype of acne lesion. Thirty percent of patients were deemed responders to this treatment with respect to improvement in their inflammatory lesion counts, while only 7% of patients responded in terms of noninflammatory lesion counts.

CONCLUSIONS

PDT with the treatment regimen employed here may be beneficial for a subgroup of patients with inflammatory acne.

Bacterial resistance to antibiotics in acne vulgaris: an in vitro study

Background:

Acne vulgaris is one of the most common skin disorders in youth especially during the puberty.

Objective:

This in vitro study was performed to determine the antibiotic resistance and sensitivity in acne vulgaris.

Materials and Methods:

Samples were collected from normal skin and nodulocystic and pustular skin lesions of one hundred youngsters (64 girls, 36 boys) among college students in the age range of 18-24 years old. The specimens were cultured individually on blood agar and Muller-Hinton media. The cultures were then incubated under both aerobic and anaerobic conditions for 2 to 7 days. Bacteria were identified and their resistance to common antibiotics was evaluated according to the standard procedures.

Results:

In aerobic culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 41% of subjects, Staphylococcus epidermidis in 53% and Micrococcus spp in 45% of subjucts. In anaerobic bacterial culture of pustular and nodulocystic skin lesions, Staphylococcus aureus was present in 39%, Propionibacterium acne in 33% and Staphylococcus epidermidis in 21% of subjects. The results of present study revealed that clindamycin and erythromycin were the least effective antibiotics for Propionibacterium acne while tetracycline was the least effective for Staphylococcus aureus in vitro. A synergic effect of benzoyl peroxide, erythromycin or clindamycin was noticed. Rifampin was the most effective antibiotic in vitro.

Conclusion:

Our results showed that rifampin was the most sensitive antibiotic in vitro for acne vulgaris. To achieve a better treatment, a combination of rifampin with other antibiotics may be more efficient. We suggest in vivo studies for better evaluation and treatment of acne patients with rifampin.

[A prospective, randomized, open and comparative study to evaluate the safety and efficacy of blue light treatment versus a topical benzoyl peroxide 5% formulation in patients with acne grade II and III]

BACKGROUND

Many acne patients improve after exposure to sunlight and there are many reports about the efficacy of blue light phototherapy on acne lesions.

OBJECTIVES

The purpose of this study was to evaluate efficacy and safety of blue light treatment versus topical benzoyl peroxide 5% formulation in patients with acne grades II and III.

METHODS

Sixty volunteers with facial acne were included and evaluated in 5 visits: the first one for screening, another 3 held on days 7, 14 and 28 of treatment, and the last one after 14 days of the end of treatment. Thirty of them were irradiated with Blue Light (8 times, twice a week) and the other thirty were treated with topical Benzoyl Peroxide 5% formulation, auto-applied twice a day, every day. We assessed the severity of acne by counting the lesions and analyzing the photographs.

RESULTS

The improvement achieved by the blue light was the same as the one with benzoyl peroxide, regardless of the type of lesion (p 0.05). Otherwise, the side effects were less frequent in the group treated with blue light.

CONCLUSIONS

Blue light irradiation was as effective as benzoyl peroxide in acne treatment grades II and III but there were fewer side effects.

Photodynamic therapy for localized infections--state of the art

Photodynamic therapy (PDT) was discovered over 100 years ago by observing the killing of microorganisms when harmless dyes and visible light were combined in vitro. Since then it has primarily been developed as a treatment for cancer, ophthalmologic disorders and in dermatology. However, in recent years interest in the antimicrobial effects of PDT has revived and it has been proposed as a therapy for a large variety of localized infections. This revival of interest has largely been driven by the inexorable increase in drug resistance among many classes of pathogen. Advantages of PDT include equal killing effectiveness regardless of antibiotic resistance, and a lack of induction of PDT resistance. Disadvantages include the cessation of the antimicrobial effect when the light is turned off, and less than perfect selectivity for microbial cells over host tissue. This review will cover the use of PDT to kill or inactivate pathogens in ex vivo tissues and in biological materials such as blood. PDT has been successfully used to kill pathogens and even to save life in several animal models of localized infections such as surface wounds, burns, oral sites, abscesses and the middle ear. A large number of clinical studies of PDT for viral papillomatosis lesions and for acne refer to its antimicrobial effect, but it is unclear how important this microbial killing is to the overall therapeutic outcome. PDT for periodontitis is a rapidly growing clinical application and other dental applications are under investigation. PDT is being clinically studied for other dermatological infections such as leishmaniasis and mycobacteria. Antimicrobial PDT will become more important in the future as antibiotic resistance is only expected to continue to increase.

Photosensitizer-antibiotic conjugates: a novel class of antibacterial molecules

Bacterial resistance to a variety of antibiotics has led to intensive research into the effect of photosensitizers as a cytotoxic agent against bacterial cells. In this study, we synthesized the following conjugates with or without a linker: rose bengal-penicillanic acid (RBPA), rose bengal-linker-penicillanic acid (RBLPA) and rose bengal-linker-kanamycin (RBLKAN). The antibacterial activity of these conjugates was examined on Staphylococcus aureus and Escherichia coli. Exposure of the cultures to 100 J cm(-2) showed that the minimum inhibitory concentration (MIC) of RBPA, RBLPA and RBLKAN on S. aureus was 0.195, 0.156 and 0.004 microm, respectively. The MIC of RBPA, RBLPA and RBLKAN on E. coli was 1.56, 2.5 and 0.156 microm, respectively. In dark control experiments, the MIC of these conjugates was not detected until a concentration that was 16-fold that of the MIC found in the light experiments. RBPA and RBLPA as well as RBLKAN are bactericidal for both bacterial cells. Total eradication of S. aureus and E. coli was observed with RBLKAN (0.078 and 20 microm 16 J cm(-2), respectively). Under these conditions, scanning electron microscopic analysis showed significant damage to these bacteria. However, the photosensitizer and antibiotics individually were not effective.

Treatment of Helicobacter pylori infection with intra-gastric violet light phototherapy: a pilot clinical trial

BACKGROUND AND OBJECTIVE

Helicobacter pylori infects the mucus layer of the human stomach and causes peptic ulcers and adenocarcinoma. We have previously shown that H. pylori accumulates photoactive porphyrins making the organism susceptible to inactivation by light, and that small spot endoscopic illumination with violet light reduced bacterial load in human stomachs. This study assessed the feasibility and safety of whole-stomach intra-gastric violet phototherapy for the treatment of H. pylori infection.

STUDY DESIGN/MATERIALS AND METHODS

A controlled, prospective pilot trial was conducted using a novel light source consisting of laser diodes and diffusing fibers to deliver 408-nm illumination at escalating total fluences to the whole stomach. Eighteen adults (10 female) with H. pylori infection were treated at three U.S. academic endoscopy centers. Quantitative bacterial counts were obtained from biopsies taken from the antrum, body, and fundus, and serial urea breath tests.

RESULTS

The largest reduction in bacterial load was in the antrum (>97%), followed by body (>95%) and fundus (>86%). There was a correlation between log reduction and initial bacterial load in the antrum. There was no dose-response seen with increasing illumination times. The urea breath test results indicated that the bacteria repopulated in days following illumination.

CONCLUSION

Intra-gastric violet light phototherapy is feasible and safe and may represent a novel approach to eradication of H. pylori, particularly in patients who have failed standard antibiotic treatment. This was a pilot study involving a small number of patients. Further research is needed to determine if phototherapy can be effective for eradicating H. pylori.

Investigation of critical inter-related factors affecting the efficacy of pulsed light for inactivating clinically relevant bacterial pathogens

AIMS

To investigate critical electrical and biological factors governing the efficacy of pulsed light (PL) for the in vitro inactivation of bacteria isolated from the clinical environment. Development of this alternative PL decontamination approach is timely, as the incidence of health care-related infections remains unacceptably high.

METHODS AND RESULTS

Predetermined cell numbers of clinically relevant Gram-positive and Gram-negative bacteria were inoculated separately on agar plates and were flashed with <or=60 pulses of broad-spectrum light under varying operating conditions, and their inactivation measured. Significant differences in inactivation largely occurred depending on the level of the applied lamp discharge energy (range 3.2-20 J per pulse), the amount of pulsing applied (range 0-60 pulses) and the distance between light source and treatment surface (range 8-20 cm) used. Greater decontamination levels were achieved using a combination of higher lamp discharge energies, increased number of pulses and shorter distances between treatment surface and the xenon light source. Levels of microbial sensitivity also varied depending on the population type, size and age of cultures treated. Production of pigment pyocynanin and alginate slime in mucoid strains of Pseudomonas aeruginosa afforded some protection against lethal action of PL; however, this was evident only by using a combination of reduced amount of pulsing at the lower lamp discharge energies tested. A clear pattern was observed where Gram-positive bacterial pathogens were more resistant to cidal effects of PL compared to Gram negatives. While negligible photoreactivation of PL-treated bacterial strains occurred after full pulsing regimes at the different lamp discharge energies tested, some repair was evident when using a combination of reduced pulsing at the lower lamp discharge energies. Strains harbouring genes for multiple resistances to antibiotics were not significantly more resistant to PL treatments. Slight temperature rises (<or=4.2 degrees C) were measured on agar surfaces after extended pulsing at higher lamp discharge energies. Presence of organic matter on treatment surface did not significantly affect PL decontamination efficacy, nor did growth of PL-treated bacteria on selective agar diminish survival compared to similarly treated bacteria inoculated and enumerated on nonselective agar plates.

CONCLUSIONS

Critical inter-related factors affecting the effective and repeatable in vitro decontamination performance of PL were identified during this study that will aid further development of this athermal process technology for applications in health care and in industry. Very rapid reductions (c. 7 log(10) CFU cm(-2) within <or=10 pulses) occurred using discharge energy of 20 J for all tested clinically relevant bacteria under study when treated at 8 cm distance from xenon light source. While no resistant flora is expected to develop for treatment of microbial pathogens on two-dimensional surfaces, careful consideration of scale up factors such as design and operational usage of this PL technique will be required to assure operator safety.

SIGNIFICANCE AND IMPACT OF THE STUDY

Findings and conclusions derived from this study will enable further development and optimization of this decontamination technique in health care and in food preparation settings, and will advance the field of nonthermal processing technologies.

Evaluation of pulsed light and radiofrequency combined for the treatment of acne vulgaris with histologic analysis of facial skin biopsies

BACKGROUND

Light and radiofrequency (RF) devices have recently been used to treat acne in selected patients.

OBJECTIVE

To investigate the safety and efficacy of a combination of pulsed light and RF energy for the treatment of acne. Materials and methods. Thirty-two patients with moderate acne were treated twice weekly for four weeks with the Aurora AC (Syneron Medical Ltd, Yokneam, Israel), a combination of pulsed light and RF energy. Twenty-five patients completed the study. In four patients, the number of hair follicles showing perifolliculitis, the diameters of hair follicles, the diameters of sebaceous glands, and expressions of heat shock protein 70 and procollagen-1 were evaluated before and after treatment.

RESULTS

The mean lesion count was reduced by 47% (p < 0.05) after eight treatments. Adverse effects-erythema, tingling, and burning-were mild and temporary. The percentage of follicles with perifolliculitis decreased from 58% to 33%, sebaceous gland areas decreased from 0.092 mm2 to 0.07 mm2, and heat shock protein 70 and procollagen-1 expressions did not change.

CONCLUSION

The combination of optical and RF energies may be an alternative nonablative modality for the treatment of moderate acne. Clinical improvement may be partly due to reductions in both perifollicular inflammation and sebaceous gland areas.

A review of lasers and light sources in the treatment of acne vulgaris

There are various treatment modalities for acne vulgaris including topical and oral therapy as well as microdermabrasion and chemical peels. Recently, there has been an emergence of novel laser and light sources as a means for treating acne vulgaris. This article will review the advances of laser and light sources in the treatment of acne vulgaris.

New insights into the management of acne: an update from the Global Alliance to Improve Outcomes in Acne group

The Global Alliance to Improve Outcomes in Acne published recommendations for the management of acne as a supplement to the Journal of the American Academy of Dermatology in 2003. The recommendations incorporated evidence-based strategies when possible and the collective clinical experience of the group when evidence was lacking. This update reviews new information about acne pathophysiology and treatment-such as lasers and light therapy-and relevant topics where published data were sparse in 2003 but are now available including combination therapy, revision of acne scarring, and maintenance therapy. The update also includes a new way of looking at acne as a chronic disease, a discussion of the changing role of antibiotics in acne management as a result of concerns about microbial resistance, and factors that affect adherence to acne treatments. Summary statements and recommendations are provided throughout the update along with an indication of the level of evidence that currently supports each finding. As in the original supplement, the authors have based recommendations on published evidence as much as possible.

In vitro evaluation of antibacterial, anticollagenase, and antioxidant activities of hop components (Humulus lupulus) addressing acne vulgaris

Seven naturally derived components from hop plant (Humulus lupulus L.) extracts were tested for evaluation of biological activities affecting acne vulgaris. Five strains, Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, Kocuria rhizophila and, Staphylococcus pyogenes, were selected as the main acne-causing bacteria. Hop extracts xanthohumol and the lupulones showed strong inhibitory activities against all of the strains. Although hydrogenated derivatives did not show the same level of activity, naturally occurring xanthohumol, humulones, and lupulones all showed moderate to strong anticollagenase inhibitory activities. Antioxidant capacity was also evaluated with seven different methods based on different reactive oxygen species. Xanthohumol showed the highest activity in total oxygen radical absorbance capacity as well as singlet oxygen absorbance capacity.

The practicalities of photodynamic therapy in acne vulgaris

A staple clinical skill in a dermatologist's repertoire is the ability to treat acne vulgaris effectively. Light-based therapies such as photodynamic therapy (PDT) widen the therapeutic options available for acne. Numerous review articles have agreed on the answer to core questions such as: 'Does PDT work?' and 'Which acne lesions respond best to PDT?' They conclude that PDT is especially useful in inflammatory acne and may be superior to light therapy alone. This literature review seeks to offer guidance regarding treatment-specific queries about the photosensitizer, route of administration, treatment intervals, light sources and patient selection. Ovid Medline, PubMed and EMBASE database searches were executed between January 2007 and March 2008. Due to the scarcity of data, all five randomized trials, four of which were at least investigator blinded and controlled, 12 open clinical studies, two case reports and two abstracts published in English were considered. Four hundred and nineteen patients were recruited. As the quality of the data was suboptimal in a significant number of articles, the conclusions are drawn in very broad strokes: topical short-contact (90 min or less) 5-aminolaevulinic acid or methyl aminolaevulinate using a noncoherent light source at 2-4-week intervals for a total of two to four treatments produces the greatest clinical effect. Papulopustular acne is more responsive and all Fitzpatrick skin types are eligible. However, patients with skin types I-III have a reduced risk of postinflammatory hyperpigmentation seen in darker skin types. These treatment parameters demonstrate a good side-effect profile resulting in acne remission for at least 3 months to a year in a relatively cost-effective manner. Well-designed nonsplit-face randomized controlled trials would offer further guidance, especially for queries surrounding the light source and illumination schemes.

Inactivation of bacterial pathogens following exposure to light from a 405-nanometer light-emitting diode array

This study demonstrates the susceptibility of a variety of medically important bacteria to inactivation by 405-nm light from an array of light-emitting diodes (LEDs), without the application of exogenous photosensitizer molecules. Selected bacterial pathogens, all commonly associated with hospital-acquired infections, were exposed to the 405-nm LED array, and the results show that both gram-positive and gram-negative species were successfully inactivated, with the general trend showing gram-positive species to be more susceptible than gram-negative bacteria. Detailed investigation of the bactericidal effect of the blue-light treatment on Staphylococcus aureus suspensions, for a range of different population densities, demonstrated that 405-nm LED array illumination can cause complete inactivation at high population densities: inactivation levels corresponding to a 9-log(10) reduction were achieved. The results, which show the inactivation of a wide range of medically important bacteria including methicillin-resistant Staphylococcus aureus, demonstrate that, with further development, narrow-spectrum 405-nm visible-light illumination from an LED source has the potential to provide a novel decontamination method with a wide range of potential applications.

The Asian dermatologic patient: review of common pigmentary disorders and cutaneous diseases

The Asian patient with Fitzpatrick skin types III-V is rarely highlighted in publications on cutaneous disorders or cutaneous laser surgery. However, with changing demographics, Asians will become an increasingly important group in this context. Although high melanin content confers better photoprotection, photodamage in the form of pigmentary disorders is common. Melasma, freckles, and lentigines are the epidermal disorders commonly seen, whilst nevus of Ota and acquired bilateral nevus of Ota-like macules are common dermal pigmentary disorders. Post-inflammatory hyperpigmentation (PIH) occurring after cutaneous injury remains a hallmark of skin of color. With increasing use of lasers and light sources in Asians, prevention and management of PIH is of great research interest. Bleaching agents, chemical peels, intense pulsed light (IPL) treatments, and fractional skin resurfacing have all been used with some success for the management of melasma. Q-switched (QS) lasers are effective for the management of epidermal pigmentation but are associated with a high risk of PIH. Long-pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers and IPL sources pose less of a PIH risk but require a greater number of treatment sessions. Dermal pigmentary disorders are better targeted by QS ruby, QS alexandrite, and QS 1064-nm Nd:YAG lasers, but hyper- and hypopigmentation may occur. Non-ablative skin rejuvenation using a combination approach with different lasers and light sources in conjunction with cooling devices allows different skin chromophores to be targeted and optimal results to be achieved, even in skin of color. Deep-tissue heating using radiofrequency and infra-red light sources affects the deep dermis and achieves enhanced skin tightening, resulting in eyebrow elevation, rhytide reduction, and contouring of the lower face and jawline. For management of severe degrees of photoaging, fractional resurfacing is useful for wrinkle and pigment reduction, as well as acne scarring. Acne, which is common in Asians, can be treated with topical and oral antibacterials, hormonal treatments, and isotretinoin. Infra-red diode lasers used with a low-fluence, multiple-pass approach have also been shown to be effective with few complications. Fractional skin resurfacing is very useful for improving the appearance of acne scarring. Hypertrophic and keloid scarring, another common condition seen in Asians, can be treated with the combined used of intralesional triamcinolone and fluorouracil, followed by pulsed-dye laser. Esthetic enhancement procedures such as botulinum toxin type A and fillers are becoming increasingly popular. These are effective for rhytide improvement and facial or body contouring. We highlight the differences between Asian skin and other skin types and review conditions common in skin of color together with treatment strategies.