Bacillus oleronius and Demodex mite infestation in patients with chronic blepharitis

Fabrication and efficacy assessment of combination of brimonidine and ivermectin for treatment of papulopustular rosacea

BACKGROUND & AIM

Rosacea is a chronic inflammatory, multifactorial disease for which combination therapy could be an effective treatment. In this study, we evaluate the effect of the combination therapy of brimonidine 0.33% and ivermectin 1% as a single cream for the treatment of papulopustular rosacea.

METHOD

A stable and appropriate formulation was prepared by adding the aqueous phase to the lipid phase while being stirred. The stability and physicochemical properties of the formulation were evaluated under accelerated conditions. Twelve patients (36-60 years) with mild to moderate papulopustular rosacea and a Demodex count of five or more were treated with the combination of brimonidine 0.33% and ivermectin 1% cream. Clinician's Erythema Assessment (CEA), Patients Self-Assessment (PSA), skin erythema (ΔE) and lightness (ΔL), and skin biophysical parameters including transepidermal water loss (TEWL), skin hydration, pH, and sebum content, as well as erythema and melanin index and ultrasound parameters, were measured before treatment and 4 and 8 weeks after. Adverse drug reactions were also recorded.

RESULTS

CEA and PSA decreased significantly from 3 to 2 after 8 weeks, respectively (p-value = 0.014 for CEA and 0.010 for PSA). ΔE and ΔL, as well as skin erythema index and TEWL improved after 8 weeks of treatment (p < 0.05). Two patients withdrew from the study in the first week because of local adverse effects; one developed flushing following treatment and left the investigation after 4 weeks and another patient withdrew from the study after 4 weeks due to deciding to become pregnant.

CONCLUSION

Eight-week treatment with the combination of brimonidine 0.33% and ivermectin 1% was shown to be effective for improvement of erythema and inflammatory lesions in mild to moderate papulopustular rosacea.

Rosacea: Pathogenesis and Therapeutic Correlates

Rosacea is a chronic inflammatory condition of which there is no cure. The pathogenesis of rosacea is likely multifactorial, involving genetic and environmental contributions. Current understanding suggests that pro-inflammatory pathways involving cathelicidins and inflammasome complexes are central to rosacea pathogenesis. Common rosacea triggers modulate these pathways in a complex manner, which may contribute to the varying severity and clinical presentations of rosacea. Established and emerging rosacea treatments may owe their efficacy to their ability to target different players in these pro-inflammatory pathways. Improving our molecular understanding of rosacea will guide the development of new therapies and the use of combination therapies.

Long-Term Outcomes of 6-Week Treatment of Lotilaner Ophthalmic Solution, 0.25%, for Demodex Blepharitis: A Noninterventional Extension Study

PURPOSE

The aim of this study was to evaluate the long-term outcomes of lotilaner ophthalmic solution, 0.25%, in the treatment of Demodex blepharitis.

METHODS

This observational, extension study included patients with Demodex blepharitis (N = 239) who completed the Saturn-1 study and presented for the day 180 visit. All participants were assessed at days 180 and 365 after the initiation of 6-week treatment with the study drug or its vehicle.

RESULTS

The proportion of patients with 0 to 2 collarettes (grade 0) was significantly higher in the study group (N = 128 patients) than in the control group (N = 111 patients) (39.8% vs. 2.7% at day 180 and 23.5% vs. 2.9% at day 365; P < 0.0001). Similarly, the proportion of patients with ≤10 collarettes (collarette grade 0-1) in the study group was significantly higher than in the control group (70.3% vs. 18.0% at day 180 and 62.6% vs. 21.9% at day 365; P < 0.0001). In the study group, erythema continued to improve even after completion of the 6-week lotilaner treatment. No serious ocular adverse events were observed in the study group, and there was 1 treatment-related ocular adverse event in the study group, which was considered mild.

CONCLUSIONS

After 6-week treatment with lotilaner ophthalmic solution, 0.25%, for Demodex blepharitis, no long-term concerns were observed during 1 year of follow-up. A high proportion of patients with 0 to 2 collarettes (grade 0) or ≤10 collarettes (collarette grade of 0 or 1) was observed throughout 1 year of follow-up, indicating that the efficacy of lotilaner ophthalmic solution, 0.25%, against Demodex blepharitis may last well after completion of therapy.

Demodex Species and Culturable Microorganism Co-Infestations in Patients with Blepharitis

We aimed to determine the prevalence of Demodex spp. and bacterial infection in patients with blepharitis and also to investigate the relationship between culturable microorganisms and Demodex spp. in this study. The study included patients diagnosed with blepharitis (n = 128) and volunteers without ocular problems (n = 113). Eyelash sampling was performed by epilating eight lashes, which were then tested for Demodex spp. using a light microscope. The examination consisted of assessing the patient's vision with and without ocular correction and tonus in both eyes and a careful examination of the anterior segment of both eyes. Bacterial identification was performed based on morphological, physiological, and biochemical methods. The prevalence of Demodex spp. was 8.0% in patients from the control group and all patients with blepharitis. Isolated forms of Demodex spp. were detected in all infested patients in the control group and in 58% of patients with blepharitis. A total of 35% of patients with blepharitis had from three to nine forms of Demodex spp., and 7% of patients with blepharitis had more than 10 mites in every field of vision. We found a statistically significant relationship between Demodex spp. infestation and the occurrence of eye dryness and sensations of burning and tearing, redness of the conjunctiva, feeling of a foreign body, loss of eyelashes, Meibomian gland dysfunction, and cylindrical dandruff. There were statistically significant relationships between Demodex sp. infestation and the presence of hyperopia, Meibomian cysts, chronic eyelid inflammation, and the use of eyeglasses. There was also a statistically significant relationship between the occurrence of Demodex spp. and seborrheic dermatitis and diabetes mellitus. Culturable microorganisms of the ocular surface were found in 8.7% of participants who were uninfested and in all patients infested with D. folliculorum. We isolated Staphylococcus aureus, Acinetobacter baumannii, Streptococcus pneumoniae, Klebsiella oxytoca, and Bacillus spp. from the conjunctival sac only in patients infested with D. folliculorum. This indicates an increased probability of colonization by pathogenic bacteria in patients with demodicosis. Therefore, patients infested with D. folliculorum should undergo a microbiological examination of conjunctival swabs.

The Role of Cosmetology in an Effective Treatment of Rosacea: A Narrative Review

Rosacea is a chronic inflammatory facial skin disease usually occurring in middle-aged patients. It manifests itself as an inflammatory condition with perivascular infiltrate, dilated blood vessels, lymphoedema, hyperplasia of sebaceous glands, and disorders of connective tissue structures brought on by fibrosis. Rosacea is characterized by multifactorial inflammatory mechanisms, and therefore it requires an interdisciplinary approach including adequate skin care, topical and/or systemic therapy, and physical modalities to successfully treat the various symptoms and disease subtypes. However, data regarding the possible role of cosmetologists in rosacea remains scanty and equivocal. The objectives of cosmetology therapy include restoration and regeneration, anti-inflammatory effects, the strengthening of blood vessels and regulation of their permeability, and the regulation of keratinization. Vascular abnormalities can be targeted with specific light and laser devices. Therefore, the present paper aims to review the latest advances and summarize different aspects concerning skin care in rosacea. Particular attention has been paid to the co-operation of cosmetologists with other specialists in order to bring about the interdisciplinary management of rosacea. It is also important to keep in mind that it is usually necessary to combine various methods of treatment, as this approach is more effective than monotherapy for attaining satisfactory cosmetic results in rosacea patients.

Investigation of the Relationship Between Ocular Demodex Colonization and the Conjunctival Flora

OBJECTIVE

This study aimed to determine whether ocular Demodex colonization leads to changes in the conjunctival flora in healthy middle-aged individuals.

METHODS

This study included 70 patients who applied to an ophthalmology clinic with a complaints of presbyopia. Two eyelash specimens from the lower eyelids of both eyes were obtained from each individual. In eyelash specimens were examined for Demodex spp. by direct wet smearing under microscopy. Conjunctival culture samples were cultivated on blood agar, eosin methylene blue and chocolate agar.

RESULTS

In the 38.5% of the individuals, Demodex spp. mites were found in the eyelashes, out of which 11.4% were Demodex brevis and 27.1% Demodex folliculorum. Bacterial growth was observed in 82.9% of the samples examined. The most frequently detected bacterium was Staphylococcus epidermidis (57%).

CONCLUSION

Although Demodex spp. infestation has been shown to be related to diseases on ocular surface of eyes such as pterygium, xerophthalmia and chalazion, we did not observe that it induces changes in ocular surface flora in healthy adults.

The Efficacy and Safety of New-Generation Intense Pulsed Light in the Treatment of Meibomian Gland Dysfunction-Related Dry Eye: A Multicenter, Randomized, Patients-Blind, Parallel-Control, Non-Inferiority Clinical Trial

Introduction

This study aimed to evaluate the efficacy and safety of a new-generation intense pulsed light (IPL) device in improving the symptoms and signs of meibomian gland dysfunction (MGD)-related dry eye, and compare it with a traditional IPL device.

Methods

This multicenter randomized controlled trial enrolled 132 patients with MGD-related dry eye from two centers. Patients were randomly assigned into the new-generation IPL (Eyesis) group or traditional IPL (E-Eye) group, and then blinded to receive treatment on days 0 and 7. Ocular Surface Disease Index (OSDI), tear meniscus height (TMH), tear breakup time (TBUT), corneal fluorescein staining (CFS), Schirmer test, and meibomian gland signs were evaluated on days 0, 7, and 14. The primary outcome was defined as the effective rate of treating MGD at day 14. Any adverse events were recorded for safety assessment. Intergroup comparisons and non-inferiority analysis were performed. p values less than 0.05 were considered statistically significant.

Results

Basic information showed no significant difference between treatment groups. The intergroup difference of the effective rate was − 1.7% in the left eye and 1.6% in right eye, verifying the non-inferiority of the Eyesis device (p = 0.927). Significant improvements in OSDI, TBUT, Schirmer test, TMH, CFS, and meibomian gland signs were observed in Eyesis group on days 7 and 14 (all p < 0.05). Compared to the E-Eye group, the Eyesis group achieved more significant improvements in OSDI, TBUT, Schirmer test, TMH, and meibum quality (all p < 0.05). There was no significant difference in the incidences of adverse events between groups (p = 1.000).

Conclusions

The new-generation IPL was effective and safe in relieving the symptoms and signs of MGD-related dry eye, exhibiting a non-inferior effective rate compared to the traditional IPL. Additionally, Eyesis showed more clinical benefits over E-Eye in alleviating symptoms, increasing tear film stability and improving meibomian gland function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-022-00556-1.

Do Kinesio Tapes Increase the Skin Exposure to Pathogenic Bacteria?

BACKGROUND

Kinesio tapes (KTs) are tapes used in physical therapy and athletics. We sought to evaluate if wearing KTs for extended periods of time increases exposure to antibiotic resistant opportunistic pathogens and effects normal human skin bacteria.

METHODS

The study consisted of ten volunteers wearing nine KTs on their arms for five consecutive days. Microorganisms were isolated from fragments collected on the second and fifth day then analyzed. Bacteria were identified using the BIOLOG system. Resistance to selected antibiotics was performed using E-Test. The effect of KTs on the growth of Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus was evaluated in a diffusion-based assay.

RESULTS

We found that KTs accumulated environmental bacteria. Among 22 species 8 were opportunistic pathogens, and all of them exhibited resistance to at least one antibiotic. None of the tapes produced inhibition zones in S. aureus. One tape, Leukotape P, caused growth inhibition in non-pathogenic S. epidermidis and M. luteus. The adhesive material of the tapes inhibited the growth of all bacteria.

CONCLUSIONS

These results indicate that KTs may increase the exposure to antibiotic resistant pathogens which can accumulate from the environment. Further, extended exposure could lead to changes in normal skin microbiota, potentially contributing to increased risks of skin infections.

Uneven Index: A Digital Biomarker to Prompt Demodex Blepharitis Based on Deep Learning

Purpose: To evaluate ocular surface manifestations and morphological changes in meibomian glands (MGs) based on artificial intelligence (AI) analysis in patients with Demodex blepharitis.

Methods: In this retrospective study, 115 subjects were enrolled, including 64 subjects with Demodex blepharitis and 51 subjects without Demodex blepharitis as control group. Morphological indexes were evaluated for height, width, tortuosity, MG density, total variation, and the three types of corrected total variation as Uneven indexes.

Results: There were no statistically significant differences in all MGs’ average tortuosity and width between the two groups. The average height of all MGs and MG density were significantly lower in the Demodex blepharitis group than control group. The total variation and two types of Uneven indexes were significantly higher in the Demodex blepharitis group than in the control group. Especially the Uneven Index of total variation/MG density had an AUC of 0.822. And the sensitivity and specificity were 59.4% and 92.2%, respectively, at a cut-off value of 3971.667. In addition, Demodex blepharitis was associated with significantly lower meibum quality and expressibility, severe atrophy of MGs, a higher ocular surface disease index (OSDI), and more instability of the tear film.

Conclusion:Demodex mites are strongly associated with morphological changes in the MGs and may cause uneven gland atrophy. Therefore, the novel characteristic parameter, the Uneven index, may serve as a digital biomarker to evaluate uneven atrophy of MGs and prompt Demodex blepharitis.

Treatment of ocular Demodex infestation with topical ivermectin cream

Purpose

To evaluate the use of ivermectin 1% cream for the treatment of sleeves associated with Demodex blepharitis.

Observations

A retrospective chart review was conducted on patients with moderate to dense sleeves secondary to Demodex folliculorum, who were treated with one or two applications of topical ivermectin 1% cream. Those who had been documented photographically pre- and post-treatment were evaluated. In this series of 5 cases, ivermectin 1% cream was highly effective in reducing or eliminating sleeves, which is the primary clinical sign of D. folliculorum infestation of the eyelids.

Conclusions and Importance

A single or double application of ivermectin 1% cream is well tolerated and highly effective in reducing or eliminating the characteristic sleeves associated with Demodex blepharitis. The use of ivermectin 1% cream merits further investigation.

The Prevalence of Demodex Blepharitis in US Eye Care Clinic Patients as Determined by Collarettes: A Pathognomonic Sign

Purpose

Patients and Methods

Results

Conclusion

Demodex Infection Changes Ocular Surface Microbial Communities, in Which Meibomian Gland Dysfunction May Play a Role

INTRODUCTION

Demodex and bacteria are both components of the ocular surface micro-ecology, constituting a complex interaction. This study aims to explore how ocular surface Demodex infestation (DI) affects ocular surface microbial communities and diversity.

METHODS

We recruited 255 subjects, and examined the correlation between ocular surface mite infestation and clinical indicators such as age, blood glucose level, dry eye symptoms, and blood pressure. 16S rRNA sequencing was performed on the conjunctival swab samples of 14 patients with ocular DI (P group) and 17 healthy people (N group). For further analysis, the subjects were divided into four subgroups, i.e. N-NMGD (n = 11), N-MGD (n = 6), P-NMGD (n = 6), and P-MGD (n = 8), according to meibomian gland dysfunction (MGD) or no MGD (NMGD).

RESULTS

There was no difference in the α-diversity of ocular surface microbial communities between the DI and healthy control groups. In linear discriminant analysis effect size (LEfSe), there were more Acinetobacter, Novosphingobium, and Anoxybacillus in the DI group and fewer Novosphingobium, Lactobacillus, and Candidatus Microthrix in the healthy control group. P-NMGD had more Thermaceae and fewer Pseudomonas than P-MGD. There were more Bacteroidetes in N-NMGD than in N-MGD. The α-diversity of P-NMGD was lower than that of N-NMGD (Shannon index, P = 0.027). At the same time, the α-diversity of N-MGD was lower than that of N-NMGD (Shannon, Simpson, and dominance index, P = 0.048). There was no significant difference in β-diversity or in the primary flora at the phylum and genus levels between groups and subgroups.

CONCLUSION

DI had no significant effect on the diversity of ocular surface microbial communities. DI primarily changed the dominant flora and relative abundance of ocular surface microbial communities. MGD may play an important role in this process.

Investigation of the Demodex Lid Infestation with in Vivo Confocal Microscopy versus Light Microscopy in Patients with Seborrheic Blepharitis

Aim: The comparison of the diagnostic efficiency of a reference method (light microscopy [LM] using 10% potassium hydroxide [KOH]) with the use of 100% alcohol to in vivo confocal microscopy (IVCM) for the detection of Demodex eyelid infestation in seborrheic blepharitis patients.Methods: Eyelashes were epilated from the right eyes for the reference method and the left eyes for the alcohol group in 58 eyes of 29 patients. IVCM was used on the left eyes. The primary outcomes were the number of Demodex mites per lash and the rate of Demodex positivity (≥1 mite).Results: The rate of Demodex positivity was similar among the three groups (KOH: 82.8%, alcohol: 86.2%, IVCM: 72.4%; p >.05). The mean number of mites per lash in the KOH group (1.5 ± 1.3) was higher than in the alcohol (0.9 ± 0.6, p =.041) and IVCM groups (0.9 ± 0.9, p =.036).Conclusion: KOH was found to be superior in terms of the quantification of mites compared to alcohol and IVCM.

Microbes of the human eye: Microbiome, antimicrobial resistance and biofilm formation

BACKGROUND

The review focuses on the bacteria associated with the human eye using the dual approach of detecting cultivable bacteria and the total microbiome using next generation sequencing. The purpose of this review was to highlight the connection between antimicrobial resistance and biofilm formation in ocular bacteria.

METHODS

Pubmed was used as the source to catalogue culturable bacteria and ocular microbiomes associated with the normal eyes and those with ocular diseases, to ascertain the emergence of anti-microbial resistance with special reference to biofilm formation.

RESULTS

This review highlights the genetic strategies used by microorganisms to evade the lethal effects of anti-microbial agents by tracing the connections between candidate genes and biofilm formation.

CONCLUSION

The eye has its own microbiome which needs to be extensively studied under different physiological conditions; data on eye microbiomes of people from different ethnicities, geographical regions etc. are also needed to understand how these microbiomes affect ocular health.

Association Between Demodex Infestation and Ocular Surface Microbiota in Patients With Demodex Blepharitis

Purpose: The aim of this study was to compare the ocular microbial communities in humans with and without demodex blepharitis in order to elucidate the relationship between ocular microorganisms and demodex infestation. Methods: Bacterial 16S rRNA genes of conjunctival sac samples from 30 demodex blepharitis patients and 14 healthy controls were sequenced using a pyrosequencing method, and their bacterial community structures were compared by bioinformatics. Results: Bacterial community clustering of conjunctival sac in the demodex blepharitis group were significantly distinct from the healthy control group, with significantly higher relative abundances of Firmicutes and Corynebacterium at the phyla level, as well as higher abundances of Lactobacillus and Bifidobacterium at the genus level. The relative abundance of Staphylococcus epidermidis (0.07-2.27%) was positively correlated with the demodex amount and modified OSDI. The major potential factors contribute to demodex blepharitis were Bacilli, Firmicutes, Cyanobacteria, Lactobacillus and Streptophyta. Conclusions: Patients with demodex blepharitis have varying degrees of bacterial microbiota imbalance in the conjunctival sac. Demodex serving as vectors to transfer both skin and environmental flora might be the potential mechanism. In addition, the number and type of demodex affect the specific ocular surface bacteria, presenting as ocular discomfort and obvious signs of blepharitis.

Ocular Demodex: a systematic review of the clinical literature

PURPOSE

There is increasing clinical and research interest in the potential contribution of Demodex to ocular surface disease. The aim of this systematic review was to summarise and synthesise current clinical evidence relating to the aetiology, diagnosis and treatment of ocular Demodex.

RECENT FINDINGS

A comprehensive literature search was performed in OVID Medline, OVID Embase, and clinical trial registries, for studies published between 1990 and August 2019, examining Demodex on the ocular surface. The review included primary clinical research studies and systematic reviews of primary clinical research studies, where Demodex was considered in the context of the ocular surface and/or adnexa. Studies were categorised using the National Health and Medical Research Council evidence hierarchy. Risk of bias assessment was performed using validated tools for studies categorised as providing Level I or II evidence. A total of 87 studies were eligible for inclusion, including two systematic reviews. Most studies (60%) were observational, describing the prevalence of ocular Demodex in different clinical populations. There was a high degree of variability in the epidemiological data derived from cross-sectional aetiology studies. There was mostly consistent evidence to support an association between ocular Demodex and chronic blepharitis. Seven diagnostic test-accuracy studies were identified, which considered a range of techniques, including slit lamp examination for cylindrical eyelash collarettes and/or eyelash manipulation techniques, light microscopic evaluation of epilated eyelashes and in vivo confocal microscopy. There is currently no accepted gold-standard diagnostic method for ocular Demodex. For intervention studies, there was one systematic review, 11 published randomised trials, six trial registry entries, and nine case series. Despite a number of recent trials, the appropriate treatment regimen for ocular Demodex (including the optimal criteria and timing of an intervention) is not clearly established.

CONCLUSIONS

This comprehensive narrative synthesis has captured the landscape of clinical evidence relating to the prevalence, aetiology, diagnosis and treatment of ocular Demodex. There remain opportunities to enhance understanding of its role in ocular surface disease, best diagnostic approaches and optimal treatment protocols.

Study on the Relationship Between Microbial Composition and Living Environment in Important Medical Mites Based on Illumina MiSeq Sequencing Technology

The microbiota of mites is closely related to their growth, development, and pathogenicity. Therefore, it is necessary to study the bacteria in mites. Here, for the first time, based on 16s rRNA V3-V4 region, the microbiota of 45 samples of nine species in six families of medically important mites were analyzed using Illumina MiSeq sequencing technique. The results showed that, at the phylum level, Proteobacteria (56.20-86.40%) were the dominant, followed by Firmicutes (6.41-19.43%), Bacteroidetes (5.56-13.38%) and Actinobacteria (1.93-28.07%). But at the genera the microbiota of mites are different, showing four characteristics: 1) The microbiota is related to the parasitic host. Demodex folliculorum (Acariforms: Demodicidae) and D. brevis (Acariforms: Demodicidae), both parasitizing humans, showed similar microbial composition, as did D. canis (Acariforms: Demodicidae) and Sarcoptes scabiei canis (Acariforms: Sarcoptidae) parasitizing dogs, but D. caprae (Acariforms: Demodicidae) parasitizing sheep showed unique microbial community; 2) The microbiota is related to mite's species. Dermatophagoides farinae and Cheyletus malaccensis (Acariforms: Cheyletidae), both collecting from flour, show respective microbial composition; 3) The microbiota is related to the life stage. There were differences in microbiota between adults and larvae of D. farinae, but no differences observed in Psoroptes cuniculi (Acariforms: Psoroptidae); and 4) The microbiota is related to the blood-feeding state. The microbiota of blood-fed Ornithonyssus bacoti (Parasitiformes: Macronyssidae) adults was significantly higher than that of unfed adults. This indicates that the microbiota of mites is affected by mite species, parasitic host, growth stage and habitat. Therefore, understanding these influencing factors will have a very important guiding significance for the prevention and control of mite-borne diseases.

Ocular bacterial infections: Pathogenesis and diagnosis

The human eye is a rigid asymmetric structure with unique defence system. Despite considerable resident microbiota, eye is exposed to external environment where a range of microorganisms also inhabits. Opportunistically, some of these microorganisms could associate with eye pathogen that could contact incidentally, leading to destructive visual consequences. Among such microbiota, bacteria form the major proportion concerning ocular complications worldwide. The succession of genome based approach through 16S rRNA gene based identification tremendously augmented the knowledge on diversity of ocular surface bacteria. Such evidence suggests that while few bacteria contribute towards normal ocular functions, considerable number of bacteria play active role in pathophysiology of ocular diseases. Thus, understanding the complexity of ocular microflora not only throw light on their critical role towards normal function of the eye, but also enlighten on certain visual exigencies. Under these circumstances, development of a rapid, reliable and cost effective method is essential that eventually evolve as a routine diagnostic protocol. Such precise prognostic modalities facilitate ophthalmologists to formulate pioneering therapeutics towards challenging ocular diseases.

Pre-Treatment and Post-Treatment Demodex Densities in Patients under Immunosuppressive Treatments

Background and Objectives: Demodex species are common obligatory parasites and normally present in low number in human beings. Immunosuppression was suggested to be associated with increased density of Demodex mites. Systemic glucocorticoids, cyclosporine, methotrexate, and azathioprine are commonly used immunosuppressive agents. We aim to determine the pre- and post-treatment Demodex densities in patients receiving immunosuppressive therapy and compare with those of healthy subjects. Materials and Methods: Demodex density was investigated at the beginning, first, and third months of the immunosuppressive therapy in 45 patients who received methotrexate, cyclosporine, systemic steroid, or azathioprine treatments and in 45 healthy subjects at the same time as the patients. Five standardized skin surface biopsies were taken from cheeks, forehead, nose, and chin of the patients and control group. The presence of five or more parasites in 1 cm² area was considered as positive. Results: Demodex test was negative at the beginning of the treatment in all patients. Demodex test was positive in one patient in the first and third months of treatment and in three patients only in the third month of treatment. In the control group, Demodex test was determined as positive in just one healthy individual at the beginning, first and third months of the study. When the patient and control groups were evaluated in terms of Demodex number, there was a statistically significant difference in Demodex density in patients treated with immunosuppressive treatment in the first and third months when compared with the control group (p < 0.05). Conclusion: Immunosuppressive treatment might increase the number of Demodex mites and demodicidosis should be kept in mind in patients on immunosuppressive treatment.

Real-Time Video Microscopy of In Vitro Demodex Death by Intense Pulsed Light

Objective: To directly observe the in vitro real-time effects of intense pulsed light (IPL) on a Demodex mite extracted from an eyelash of a patient with ocular rosacea. Background: Demodex is a risk factor in the pathogenesis of oculofacial rosacea, meibomian gland dysfunction (MGD), and dry eye disease (DED). Recent studies suggested IPL to control or eradicate Demodex organisms in the periocular area. Despite encouraging reports, the direct effect of IPL on Demodex is not well understood. Methods: An eyelash infested with Demodex was epilated from a 62-year-old female patient with oculofacial rosacea. Following isolation and adherence of a mite onto a microscope slide, real-time video microscopy was used to capture live images of the organism before, during, and after administration of IPL pulses. IPL pulses were delivered with the M22 IPL (Lumenis), with IPL settings used for treatment of DED due to MGD (the "Toyos protocol"). A noncontact digital laser infrared thermometer was used to measure the temperature of the slide. Results: Before the IPL pulses, legs of the Demodex mite spontaneously moved in a repetitive and semicircular motion. During administration of IPL, spontaneous movements of the legs continued. Immediately after administration of five IPL pulses, the temperature of the slide increased from room temperature to 49°C. Immediately afterward, the Demodex mite became completely immobilized. The legs appeared retracted, smoother, less corrugated, bulkier, and less well-defined. Movement of the Demodex mite was not observed at the hourly inspections for 5 h and after 24 h following the application of IPL pulses. Conclusions: Our video directly demonstrates the effect of IPL on a live Demodex mite extracted from a freshly epilated eyelash. The results suggest that IPL application with settings identical to those used for treatment of DED due to MGD causes a complete destruction of the organism.

Use of Intense Pulsed Light to Mitigate Meibomian Gland Dysfunction for Dry Eye Disease

Dry Eye Disease (DED) is a common ocular condition that needs prompt diagnosis and careful treatment interventions. If left untreated, it can lead to numerous sight-threatening complications, including ulceration of the cornea, blepharitis, alterations of the tear film, conjunctivitis, and in severe cases, may lead to scarring, thinning, and even perforation of the cornea. Intense pulsed light (IPL) is a non-laser high-intensity light source that has shown to play a valuable role in dry eye disease. Recent evidence from various research works has shown that IPL modifies the mechanism of meibomian gland dysfunction (MGD), which helps to relieve the symptoms of DED. In this review, we demonstrated the mechanism of action of IPL, including its benefits on DED. The emerging evidence shows that the role of IPL in DED is novel and therapeutic. These results direct us to conclude that IPL is a potentially beneficial tool and essential future therapy for dry eye disease. Advances in the treatment of DED will lead to a better quality of life. However, tools to recognize potentially severe side effects of DED earlier in order to treat or prevent them must be developed.

The Skin and Gut Microbiome and Its Role in Common Dermatologic Conditions

Microorganisms inhabit various areas of the body, including the gut and skin, and are important in maintaining homeostasis. Changes to the normal microflora due to genetic or environmental factors can contribute to the development of various disease states. In this review, we will discuss the relationship between the gut and skin microbiome and various dermatological diseases including acne, psoriasis, rosacea, and atopic dermatitis. In addition, we will discuss the impact of treatment on the microbiome and the role of probiotics.

Immune mechanisms in human and canine demodicosis: A review

Demodex mites are saprophytic parasites of the mammalian skin, mostly found in or near pilosebaceous units of hairy regions. While they can be found in healthy humans and animals without causing any clinical manifestations, they were suggested to create pathogenic symptoms when they appear in high densities under favourable conditions (ie, demodicosis). Nevertheless, their role as the primary causative agent of the pathogenic conditions in humans is debated today. Canine demodicosis, which is highly prevalent in certain dog breeds, provides a valuable tool for studying the pathogenesis of human demodicosis. Canine and human demodicosis are caused by different Demodex species, and the clinical manifestations in former could be life-threatening. Nevertheless, current literature suggests similar immune responses and immune evasion mechanisms in human and canine demodicosis; cellular immunity appeared to have a central role in protection against demodicosis, and Demodex mites were shown to influence both innate and adaptive immune response to escape immune attack. The aim of this review is to summarize the relevant literature on demodicosis obtained from studies conducted on both organisms, and draw the attention to the effect of mite-associated factors (eg, microbiota) on the different clinical manifestations displayed during human and canine demodicosis.

Prevalence and Load of Demodex folliculorum and Demodex brevis (Acari: Demodicidae) in Patients With Chronic Blepharitis in the Province of Erzincan, Turkey

Chronic blepharitis is an ocular disease frequently encountered by ophthalmologists. Demodex mites can play a role in the pathogenesis of blepharitis along with bacterial agents, especially in treatment-resistant cases or recurrent cases after treatment. This study was performed to determine the prevalence and load of Demodex folliculorum (Simon) and Demodex brevis Akbulutova in chronic blepharitis patients and to assess the relationship between the prevalence and load of Demodex species and ocular symptoms. The study included 365 patients diagnosed with chronic blepharitis in clinical examination, and 175 controls without any chronic or ocular disease. In the study, two eyelashes were sampled from the lower and upper lids of the right and left eyes (a total of eight samples) of the participants. Eyelash samples were examined under a light microscope, and Demodex species were identified and counted. Demodex were detected in 79.2% (95% CI: 75-83%) of patients and 31.4% (95% CI: 24-38%) of controls in this study. D. folliculorum alone (mean: 4.96; min: 1; max: 17; P < 0.001) was detected in 72.3% of patients, in 0.7% D. brevis alone (mean: 1.00, P > 0.05), and in 27% both D. folliculorum and D. brevis (mean: 21.65; min: 2; max: 79; P < 0.001). In Demodex positive controls, only D. folliculorum (mean: 2.38; min: 1; max: 6) was detected while there was no D. brevis. Nevertheless, mean ocular symptom scores were significantly higher in Demodex positive patients than in Demodex negative patients (P < 0.001). Itching, foreign body sensation, and redness were the most common complaints in Demodex positive patients. As a result, Demodex mites were high in numbers in patients with chronic blepharitis in Erzincan. There was a positive correlation between Demodex mites and chronic blepharitis and ocular symptoms. It may be helpful to consider these findings in clinical assessment of blepharitis patients.

Intense Pulsed Light Therapy In The Treatment Of Meibomian Gland Dysfunction: Current Perspectives

Dry eye disease (DED) is among the most common condition encountered during ophthalmic practice, reducing patient's quality of life and work productivity. Most of DED cases have an evaporative component originated from a meibomian gland dysfunction (MGD). Conventional treatments such as tear substitute, warm compresses, topical anti-inflammatory agents and/or antibiotics often are not able to provide a complete and long-term relief of symptoms and signs. Intense pulsed light (IPL) has been widely used in the field of dermatology to treat various skin conditions, and it has been recently introduced in the ophthalmic practice for the management of DED due to MGD. To date, several clinical studies showed positive results of IPL as adjuvant therapy for DED in terms of both safety and efficacy. The treatment is usually well accepted among patients for its non-invasive nature; very rare are the major adverse reactions. Moreover, results can be maintained over time with periodic sessions of IPL. This review summarizes the clinical outcomes of IPL therapy in MGD patients pointing out its potential role in the therapeutic algorithm of the disease. Further clinical investigations are desirable to identify factors able to predict the positive outcomes of the procedure and therefore to select in advance those patients who best benefit from IPL therapy.

The eyelash follicle features and anomalies: A review

The primary role of eyelashes is to protect and maintain the health of the lid margin. However, the mechanisms to fulfill this role are not fully understood. Unraveling these mechanisms will stand to greatly improve the efficiency of eye care professionals' interventions in anomalies of the eyelashes. The aim of this article is to provide a review on eyelashes including highlights and new avenues for research; the biology of both the lash and its follicle; the pathophysiology and management of lash anomalies by eye care professionals; and the effect of iatrogenic factors on lashes. Using the database of Ovid MEDLINE, we reviewed studies specifically directed on human/mammalian eyelashes and key articles on current trends in scalp hair methodologies that can be applicable to lash research. The eyelash morphology, pigmentation and growth rate have been documented using techniques ranging from lash imaging to follicle immunohistochemistry. Furthermore, studies have demonstrated that the lash follicle is sensitive to many factors of the external environment, a variety of systemic/topical medications and cosmetics. Recently, aerodynamic studies using a mammalian eye model confirmed that an optimal lash length was needed so that eyelashes serve a protective role in reducing the number of particles that can reach the eye. Despite recent advances in lash research, studies are still scarce, due to the limited availability of the human lid for sampling. This review brings awareness that further research is needed with respect to eyelashes and will hopefully reduce the gap with scalp hair research.

Quantitative Analysis of the Bacteria in Blepharitis With Demodex Infestation

Bacterial infection or Demodex infestation has been reported to contribute to chronic blepharitis. The association between Demodex mites and bacterial flora in this disease remains to be elucidated. Fifty-six consecutive patients diagnosed with chronic blepharitis and 46 healthy volunteers were recruited for this study. Using specimens of three epilated eyelashes and lid margin swabs, Demodex were identified microscopically and bacteria were determined by cultures, followed by colony counting and mass spectrometry. We found 191 Demodex mites, 161 D. folliculorum and 30 D. brevis, in 45 patients. Correspondingly, 101 Demodex, 63 D. folliculorum and 38 D. brevis, were found in 21 controls (p < 0.05, both). Bacterial culture-positivity was obtained in samples (eyelashes, lid margins, or both) from 54 patients and in eyelashes from 37 controls. The total colony counts and the incidences and colony counts of Propinibacterium acnes and Staphylococcus aureus from patients’ eyelashes were significantly higher than that of the controls. Furthermore, bacterial colony counts in blepharitis patients’ eyelashes with D. folliculorum were higher than that of controls with D. folliculorum (p < 0.01). Similarly, P. acnes colonies increased significantly in patients’ eyelashes with D. folliculorum (p < 0.05). These results suggest that D. folliculorum and P. acnes have a role in the occurrence of the chronic blepharitis. Further studies are required to reveal the relationship between these two organisms in blepharitis.

Analysis of the effect of temperature on protein abundance in Demodex-associated Bacillus oleronius

A potential role for bacteria in the induction of rosacea has been suggested. The aim of this work was to characterise the effect of temperature on the production of immunostimulatory proteins by Bacillus oleronius-a bacterium to which rosacea patients show sera reactivity and which was originally isolated from a Demodex mite from a rosacea patient. The affected skin of rosacea patients is at a higher temperature than unaffected skin, and it was postulated that this might alter the protein expression pattern of B. oleronius. B. oleronius growth was reduced at 37°C compared to 30°C but resulted in increased expression of the immune-reactive 62kDa protein (1.65 fold [P < 0.05]). Proteomic analysis revealed increased abundance of a wide range of proteins involved in the stress response (e.g. stress proteins [21.7-fold increase], phosphocarrier protein HPr [438.5-fold increase], 60 kDa chaperonin [12.6-fold increase]). Proteins decreased in abundance after growth at 37°C included ferredoxin (325-fold decrease) and peptidase (244-fold decrease). This work indicates that the increased skin temperature of rosacea patients may alter the growth and protein production pattern of B. oleronius and lead to the greater production of immuo-stimulatory proteins.

Endosymbiosis and its significance in dermatology

Proposed at the beginning of the twentieth century to explain the origin of eukaryotic organelles from prokaryotes, endosymbiosis is now medically defined by various interaction patterns between microorganisms and their residing hosts, best exemplified by the bacterial endosymbiont Wolbachia identified in arthropods and filarial nematodes, which can influence normal development, reproduction, survival and transmission of the hosts. Based on the transmission modes, vertical or horizontal, and the function of the endosymbionts, the host-symbiont dependence can be divided into primary or secondary. In dermatology, the role of endosymbionts in skin ectoparasitosis has aroused great interests in the past years. Riesia pediculicola is a primary bacterial endosymbiont in body lice Pediculus humanus, and supplement their hosts with vitamin B, especially pantothenic acid. In cimicosis, the Gram-negative Wolbachia can synthesize biotin and riboflavin, which are crucial for the growth and reproduction of the bedbug Cimex lectularius. In human demodicosis and rosacea, further study is required to prove the pathogenic role of the Gram-negative bacteria Bacillus oleronius or the Gram-positive bacteria Bacillus cereus demonstrated in the Demodex mites. The high infection rate of adult female ticks Ixodes ricinus with the Gram-negative bacteria Midichloria mitochondrii present in the mitochondria in diverse ovarian cells, with the high seroprevalence rate in tick-exposed subjects, raises the possibility that this non-pathogenic endosymbiont may play a role in immune response and successful transmission of the tick-borne pathogen. The anaerobic protozoan Trichomonas vaginalis and bacteria Mycoplasma hominis are two obligate parasites in the urogenital epithelium, with partially overlapping symptoms. Intracellular localization of Mycoplasma hominis can avoid host immune response and penetration of antibiotics, while Trichomonas vaginalis infected with Mycoplasma hominis seems to have a higher cytopathic activity and amoeboid transformation rate. Further study on the biology and pathogenesis of different endosymbionts in dermatological parasitosis will help for the development of new treatment modalities.

Intense pulsed light for evaporative dry eye disease

There is a clear association between dry eye disease (DED) and skin inflammatory diseases occurring in close proximity to the eyelids, such as facial skin rosacea. Intense pulsed light (IPL) is widely accepted as a treatment for skin rosacea. A number of recent studies demonstrated that, in patients suffering from meibomian gland dysfunction (MGD), IPL therapy also reduces signs and symptoms of DED. Despite these encouraging results, in the context of DED and MGD, the mechanisms of action of IPL are not well understood. The purpose of this review was to raise the potential mechanisms of action and to discuss their plausibility.

Prospective evaluation of intense pulsed light and meibomian gland expression efficacy on relieving signs and symptoms of dry eye disease due to meibomian gland dysfunction

Purpose

The aim of this study was to estimate the efficacy of intense pulsed light (IPL), followed by meibomian gland expression (MGX), for reducing the number and severity of signs and symptoms of dry eye disease (DED) secondary to meibomian gland dysfunction (MGD).

Patients and methods

In a prospective study conducted in two sites, 40 subjects (80 eyes) with moderate to severe MGD were enrolled. Major inclusion criteria consisted of at least two of the following measures being compatible with DED in both eyes: tear breakup time (TBUT), meibomian gland score (MGS), corneal fluorescein staining (CFS), Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire, and tear film osmolarity (TFO). Enrolled patients underwent four treatment sessions, 3 weeks apart. Each treatment included the administration of 10–15 pulses of IPL on the cheeks and nose, followed by MGX of the upper and lower eyelids. TBUT, MGS, CFS, SPEED, TFO, and lipid layer thickness (LLT) were measured at baseline (BL) and at 9, 12, and 15 weeks after BL.

Results

Due to different staining methods used for TBUT measurements, TBUT and CFS were analyzed separately for each site. From BL to the final follow-up, the number of signs compatible with DED decreased from 3.3±0.1 to 1.4±0.1. TBUT improved by +93% (n=38; P<0.0001) and +425% (n=42; P<0.0001) for sites 1 and 2, respectively. SPEED, MGS, and CFS improved by −55% (n=80; P<0.0001), −36% (n=80; P<0.0001), and −58% (n=38; P<0.0001), respectively. In 20 eyes with abnormally elevated TFO at BL, TFO improved by −7% (n=20; P<0.005). LLT did not change (n=38; P=0.88).

Conclusion

In subjects with moderate to severe MGD, IPL combined with MGX reduced the number and severity of symptoms and signs of DED. Except for LLT, all examined outcome measures significantly improved after 15 weeks. These results support the efficacy of IPL + MGX in relieving both signs and symptoms of DED secondary to MGD.

Prevalence of ocular demodicosis among patients at Tertiary Care Center, Bangkok, Thailand

AIM

To determine the prevalence of ocular demodicosis by both microscopic examination and molecular detection among patients at King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok.

METHODS

One hundred individuals were enrolled in the study and were divided into five age groups. The meibomian gland dysfunction (MGD) score and qualities of cylindrical dandruff (CD) were also determined. Demodex mite infestations of eyelash samples were screened by both microscopic examination and semi-nested polymerase chain reaction (PCR).

RESULTS

The prevalence of ocular demodicosis as determined by microscopic examination was 42% [Demodex folliculorum (D. folliculorum) 41% and Demodex brevis (D. brevis) 1%]. Among patients who had ocular Demodex infestation, 69% have CD and had an average MGD score of 4; in patients without demodicosis, 15.5% had CD and had an average MGD score of 4.12. Prevalence of ocular demodicosis as determined by semi-nested PCR was 79% (D. folliculorum 78% and D. brevis 1%).

CONCLUSION

This is the first report on the prevalence of ocular demodicosis in Thailand. Patients with CD also had Demodex mites present. Semi-nested PCR is better than microscopy for Demodex infestation detection. An extensive survey with more representative samples is required to determine the prevalence in the country.

Association study of Demodex bacteria and facial dermatoses based on DGGE technique

The role of bacteria is unclear in the facial skin lesions caused by Demodex. To shed some light on this issue, we conducted a case-control study comparing cases with facial dermatoses with controls with healthy skin using denaturing gradient gel electrophoresis (DGGE) technique. The bacterial diversity, composition, and principal component were analyzed for Demodex bacteria and the matched facial skin bacteria. The result of mite examination showed that all 33 cases were infected with Demodex folliculorum (D. f), whereas 16 out of the 30 controls were infected with D. f, and the remaining 14 controls were infected with Demodex brevis (D. b). The diversity analysis showed that only evenness index presented statistical difference between mite bacteria and matched skin bacteria in the cases. The composition analysis showed that the DGGE bands of cases and controls were assigned to 12 taxa of 4 phyla, including Proteobacteria (39.37-52.78%), Firmicutes (2.7-26.77%), Actinobacteria (0-5.71%), and Bacteroidetes (0-2.08%). In cases, the proportion of Staphylococcus in Firmicutes was significantly higher than that in D. f controls and D. b controls, while the proportion of Sphingomonas in Proteobacteria was significantly lower than that in D. f controls. The between-group analysis (BGA) showed that all the banding patterns clustered into three groups, namely, D. f cases, D. f controls, and D. b controls. Our study suggests that the bacteria in Demodex should come from the matched facial skin bacteria. Proteobacteria and Firmicutes are the two main taxa. The increase of Staphylococcus and decrease of Sphingomonas might be associated with the development of facial dermatoses.

Activation of Neutrophils via IP3 Pathway Following Exposure to Demodex-Associated Bacterial Proteins

Rosacea is a chronic inflammatory condition that predominantly affects the skin of the face. Sera from rosacea patients display elevated reactivity to proteins from a bacterium (Bacillus oleronius) originally isolated from a Demodex mite from a rosacea patient suggesting a possible role for bacteria in the induction and persistence of this condition. This work investigated the ability of B. oleronius proteins to activate neutrophils and demonstrated activation via the IP3 pathway. Activated neutrophils displayed increased levels of IP1 production, F-actin formation, chemotaxis, and production of the pro-inflammatory cytokines IL-1β and IL-6 following stimulation by pure and crude B. oleronius protein preparations (2 μg/ml), respectively. In addition, neutrophils exposed to pure and crude B. oleronius proteins (2 μg/ml) demonstrated increased release of internally stored calcium (Ca(2+)), a hallmark of the IP3 pathway of neutrophil activation. Neutrophils play a significant role in the inflammation associated with rosacea, and this work demonstrates how B. oleronius proteins can induce neutrophil recruitment and activation.

Rosacea: a Clinical Review

Rosacea is a field within dermatology with new insight within immunological research and new treatment-algorithm. Patient education on rosacea and appropriate treatments is an important aspect in helping patients succeed with therapy. Treatment should be tailored to each individual patient, taking into account: symptoms, trigger factors, patients' wishes, most bothersome symptoms, psychological aspect, individual needs. A combination of clinical therapies to treat different symptoms concomitantly may offer the best possible outcomes for the patient. In this review article we describe these aspects.

Demodex species in human ocular disease: new clinicopathological aspects

Demodex brevis and Demodex folliculorum are likely ubiquitous organisms associated with human eyelashes. However, they have also been implicated in the pathogenesis of external ocular diseases. This article reviews the current literature in regards to life cycle, morphology, pathogenesis and treatment of underlying Demodex spp. infestation and outlines the previously undescribed in vivo behaviour of the mites. Images were obtained from the epilation of lashes from 404 patients seen in clinical practice. Epilated lashes were placed on a microscope slide which had been coated with optically clear hypromellose/carbomer gel (Genteal gel, Novartis pharmaceuticals corporation, East Hanover, New Jersey). Adults were identified with either dark field or standard transmission microscopy at 40-100×. Eggs and other life-cycle stages were examined at 250× magnification, with transmission microscopy giving the best image resolution. The life cycle of the mite has been reviewed and simplified according to clinical observations. Clinical signs suggestive of underlying Demodex spp. infestation have been described, and their pathogenesis was explained based on the micrographic digital images obtained. The problem of symptomatic Demodex spp. disease likely reflects an imbalance in the external ocular ecology; however, the role of Demodex spp. as a commensal should not be overlooked. Treatment should not be aimed at total eradication of the mite but rather restoring the ocular ecology to a balanced state. By revisiting the life cycle of the mite, we can identify areas where possible intervention may be effective.

[Primary human demodicosis. A disease sui generis]

Human Demodex mites (Demodex folliculorum and Demodex brevis) are unique in that they are an obligate human ectoparasite that can inhabit the pilosebaceous unit lifelong without causing obvious host immune response in most cases. The mode of symbiosis between humans and human Demodex mites is unclear, while the pathogenicity of human Demodex mites in many inflammatory skin diseases is now better understood. Primary human demodicosis is a skin disease sui generis not associated with local or systemic immunosuppression. Diagnosis is often underestimated and differentiation from folliculitis, papulopustular rosacea and perioral dermatitis is not always straightforward. Dependent on the morphology and degree of inflammation, the clinical manifestations can be classified into spinulate, papulopustular, nodulocystic, crustic and fulminant demodicosis. Therapy success can be achieved only with acaricides/arachidicides. The effective doses, optimal regimen and antimicrobial resistance remain to be determined.

Correlation between serum reactivity to Demodex-associated Bacillus oleronius proteins, and altered sebum levels and Demodex populations in erythematotelangiectatic rosacea patients

Rosacea is a chronic inflammatory condition that affects the skin of the face and the eyes. The aetiology of rosacea is not clearly established but increasing evidence suggests a potential role for bacteria in the induction of the condition. A role for Bacillus oleronius, originally isolated from within a Demodex folliculorum mite, in the aetiology of the condition has been suggested. The aim of the study was to determine whether a correlation existed between the level of sebum and the density of D. folliculorum in the skin of erythematotelangiectatic rosacea patients, and the reactivity of these patients' sera to proteins of B. oleronius. Serum reactivity to the 62 and 83 kDa B. oleronius proteins was found in 82.6 % (62/75) of the rosacea patients and in 26.9 % (14/52) of controls (P = 0.0016). In the group of rosacea patients whose sera reacted to B. oleronius proteins, the level of sebum was statistically lower than in controls (P = 0.01). The density of D. folliculorum on the face of Bacillus positive rosacea patients was statistically higher than controls (P = 0.0001). Rosacea patients demonstrated increased Demodex populations on their faces and reduced sebum levels. Their sera also showed reactivity to B. oleronius proteins, suggesting a potential role for this bacterium in the aetiology of rosacea.

Potential role of microorganisms in the pathogenesis of rosacea

Rosacea is a skin condition of abnormal inflammation and vascular dysfunction. The active contribution of a microbial agent in the development or progression of rosacea continues to be debated. Research supports the presence of commensal Demodex folliculorum mites at increased density in the skin and associates Helicobacter pylori infection of the gut with rosacea. Fewer studies implicate Staphylococcus epidermidis, Chlamydophila pneumoniae, and the Demodex-associated bacteria Bacillus oleronius. No research, however, provides a mechanism by which colonization by a microorganism translates to manifestation of the condition. Prevailing and emerging principles in the biology of the microbiome and the pathophysiology of rosacea may help to reconcile these lingering questions. Here the microorganisms implicated in rosacea are reviewed and the reaction of the microbiome to inflammation and to changes in microenvironments and macroenvironments are discussed to explain potential roles for microorganisms in rosacea pathophysiology.

Potential role of Demodex mites and bacteria in the induction of rosacea

Rosacea is a common dermatological condition that predominantly affects the central regions of the face. Rosacea affects up to 3 % of the world's population and a number of subtypes are recognized. Rosacea can be treated with a variety of antibiotics (e.g. tetracycline or metronidazole) yet no role for bacteria or microbes in its aetiology has been conclusively established. The density of Demodex mites in the skin of rosacea patients is higher than in controls, suggesting a possible role for these mites in the induction of this condition. In addition, Bacillus oleronius, known to be sensitive to the antibiotics used to treat rosacea, has been isolated from a Demodex mite from a patient with papulopustular rosacea and a potential role for this bacterium in the induction of rosacea has been proposed. Staphylococcus epidermidis has been isolated predominantly from the pustules of rosacea patients but not from unaffected skin and may be transported around the face by Demodex mites. These findings raise the possibility that rosacea is fundamentally a bacterial disease resulting from the over-proliferation of Demodex mites living in skin damaged as a result of adverse weathering, age or the production of sebum with an altered fatty acid content. This review surveys the literature relating to the role of Demodex mites and their associated bacteria in the induction and persistence of rosacea and highlights possible therapeutic options.