A novel method to control the balance of skin microflora

Microbiome modulators for atopic eczema: a systematic review of experimental and investigational therapeutics

INTRODUCTION

Atopic dermatitis (AD) is a common inflammatory cutaneous disease that arises due to dysregulation of the Th2 immune response, impaired skin barrier integrity, and dysbiosis of the skin and gut microbiota. An abundance of Staphylococcus aureus biofilms in AD lesions increases the Th2 immune response, and gut bacteria release breakdown products such as Short Chain Fatty Acids that regulate the systemic immune response.

AREAS COVERED

We aim to evaluate therapies that modulate the microbiome in humans and discuss the clinical implications of these treatments. We performed a review of the literature in which 2,673 records were screened, and describe the findings of 108 studies that were included after full-text review. All included studies discussed the effects of therapies on the human microbiome and AD severity. Oral probiotics, topical probiotics, biologics, and investigational therapies were included in our analysis.

EXPERT OPINION

Oral probiotics demonstrate mixed efficacy at relieving AD symptoms. Topical probiotics reduce S. aureus abundance in AD lesional skin, yet for moderate-severe disease, these therapies may not reduce AD severity scores to the standard of biologics. Dupilumab and tralokinumab target key inflammatory pathways in AD and modulate the skin microbiome, further improving disease severity.

Antimicrobial potentials of natural products against multidrug resistance pathogens: a comprehensive review

Antibiotic resistance is one of the critical issues, describing a significant social health complication globally. Hence, the discovery of novel antibiotics has acquired an increased attention particularly against drug-resistant pathogens. Natural products have served as potent therapeutics against pathogenic bacteria since the glorious age of antibiotics of the mid 20th century. This review outlines the various mechanistic candidates for dealing with multi-drug resistant pathogens and explores the terrestrial phytochemicals isolated from plants, lichens, insects, animals, fungi, bacteria, mushrooms, and minerals with reported antimicrobial activity, either alone or in combination with conventional antibiotics. Moreover, newly established tools are presented, including prebiotics, probiotics, synbiotics, bacteriophages, nanoparticles, and bacteriocins, supporting the progress of effective antibiotics to address the emergence of antibiotic-resistant infectious bacteria. Therefore, the current article may uncover promising drug candidates that can be used in drug discovery in the future.

Screening of Natural Molecules as Adjuvants to Topical Antibiotics to Treat Staphylococcus aureus from Diabetic Foot Ulcer Infections

Diabetic foot ulcers (DFUs) are a common result of a complex secondary complication of diabetes mellitus. More than half of DFUs become infected due to frequent colonization with Staphylococcus aureus. The use of topical antibiotics is proposed, especially in combination with natural adjuvants, to minimize the negative impacts caused by generalized use of systemic antibiotics. In this study, 13 different phytochemicals—namely chalcone, juglone, cinnamic acid, trigonelline, Furvina—and four nitrovinylfuran derivatives—guaiazulene, α-bisabolol, farnesol and nerolidol—were selected to be tested as antibiotic enhancers. After minimum inhibitory and bactericidal concentration (MIC and MBC) determination of each molecule against different strains of S. aureus, including clinical isolates from diabetic foot wounds (CECT 976, Xu212, SA 1199B, RN4220, MJMC102, MJMC109, MJMC110 and MJMC111), their potentiation effects on the antibiotics fusidic acid, mupirocin, gentamicin, oxacillin and methicillin were evaluated through the disc diffusion method. Farnesol at sub-MIC was able to restore the activity of methicillin and oxacillin on the MJMC102 and MJMC111 strains, as well as two MRSA clinical isolates, and potentiated the effect of the remaining antibiotics. The results obtained demonstrate the great potential for the topical application of phytochemicals and derivatives as antibiotic resistance modifier agents to combat multidrug resistance in bacterial wound infections.

Propanediol (and) Caprylic Acid (and) Xylitol as a New Single Topical Active Ingredient against Acne: In Vitro and In Vivo Efficacy Assays

In addition to dermatological complications, acne can affect the quality of life of individuals in numerous ways, such as employment, social habits and body dissatisfaction. According to our expertise, caprylic acid and propanediol would not have a direct action on Cutibacterium acnes. Despite this, we investigated the existence of a synergistic effect among xylitol, caprylic acid and propanediol as a mixture of compounds representing a single topical active ingredient that could benefit the treatment against acne. In vitro and in vivo assays were performed to challenge and to prove the efficacy of propanediol, xylitol and caprylic acid (PXCA) against acne. PXCA had its MIC challenged against C. acnes (formerly Propionibacterium acnes) and Staphylococcus aureus, resulting in concentrations of 0.125% and 0.25%, respectively, and it also developed antimicrobial activity against C. acnes (time-kill test). PXCA was able to reduce the 5-alpha reductase expression in 24% (p < 0.01) in comparison with the testosterone group. By the end of 28 days of treatment, the compound reduced the skin oiliness, porphyrin amount and the quantity of inflammatory lesions in participants. According to the dermatologist evaluation, PXCA improved the skin's general appearance, acne presence and size.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

A Novel Multi-Action Emollient Plus Cream Improves Skin Barrier Function in Patients with Atopic Dermatitis: In vitro and Clinical Evidence

BACKGROUND

Emollients capable of restoring the skin barrier function would extend their role beyond basic maintenance therapy in atopic dermatitis (AD).

OBJECTIVES

Investigate the effect of a novel emollient plus cream (EC; Dermoflan®) on the skin barrier in vitro and in patients with mild-to-moderate AD.

METHODS

The effect of EC on the skin barrier recovery was evaluated using a tape-stripping (TS) model. After TS, organ cultures were treated with EC (undiluted or diluted 1:1 with water) and analyzed at 18-120 h using hematoxylin and eosin, Oil Red O, immunohistochemical, and immunofluorescent techniques. In a double-blind, randomized study, EC or placebo was applied once daily for 2 months to antecubital folds of the upper and lower limbs of patients with mild-to-moderate AD in clinical remission. Epidermal thickness, vascularization, and epidermal hydration were assessed by optical coherence tomography and corneometry, respectively, at baseline, and 1 and 2 months following treatment initiation.

RESULTS

Following TS, EC treatment significantly increased epidermal thickness and lipid content versus diluent in the skin organ culture, as well as claudin-1, involucrin, and caspase-14 expression, suggesting skin barrier repair. EC treatment also decreased keratin-16 expression and increased levels of Toll-like receptors 1 and 2 versus diluent, suggesting involvement in regulating the epidermal immune response. In 20 patients randomized 1:1 to EC or placebo, EC treatment at the elbow fold/popliteal fossa significantly decreased epidermal thickness after 2 months, and the number of blood vessels at the elbow fold after 1 and 2 months, versus placebo. EC significantly improved the skin hydration after 2 months versus baseline.

CONCLUSIONS

This novel multi-action EC may help to restore epidermal homeostasis and improve the skin of patients with AD. Results indicate that this novel multi-action EC could be a valid adjuvant therapy in patients with AD. Key Message: Novel multi-action emollient cream helps to restore epidermal homeostasis and improves the skin affected by AD.

Biofilm propensity of Staphylococcus aureus skin isolates is associated with increased atopic dermatitis severity and barrier dysfunction in the MPAACH pediatric cohort

BACKGROUND

Atopic dermatitis (AD) patients are often colonized with Staphylococcus aureus, and staphylococcal biofilms have been reported on adult AD skin lesions. The commensal S epidermidis can antagonize S aureus, although its role in AD is unclear. We sought to characterize S aureus and S epidermidis colonization and biofilm propensity and determine their associations with AD severity, barrier function, and epidermal gene expression in the first US early-life cohort of children with AD, the Mechanisms of Progression of Atopic Dermatitis to Asthma in Children (MPAACH).

METHODS

The biofilm propensity of staphylococcal isolates was assessed by crystal violet assays. Gene expression of filaggrin and antimicrobial alarmins S100A8 and S100A9 was measured in keratinocyte RNA extracted from skin tape strips. Staphylococcal biofilms sampled from MPAACH skin were visualized using scanning electron microscopy.

RESULTS

Sixty-two percent of staphylococcal isolates (sampled from 400 subjects) formed moderate/strong biofilms. Sixty-eight percent of subjects co-colonized with both staphylococcal species exhibited strains that formed cooperative mixed-species biofilms. Scanning electron microscopy verified the presence of staphylococcal biofilms on the skin of MPAACH children. Staphylococcus aureus strains showing higher relative biofilm propensity compared with S epidermidis were associated with increased AD severity (P = .03) and increased lesional and nonlesional transepidermal water loss (P = .01, P = .03).

CONCLUSIONS

Our data suggest a pathogenic role for S aureus biofilms in AD. We found that strain-level variation in staphylococcal isolates governs the interactions between S epidermidis and S aureus and that the balance between these two species, and their biofilm propensity, has important implications for AD.

Prebiotic Combinations Effects on the Colonization of Staphylococcal Skin Strains

Background: An unbalanced skin microbiota due to an increase in pathogenic vs. commensal bacteria can be efficiently tackled by using prebiotics. The aim of this work was to identify novel prebiotic combinations by exerting species-specific action between S. aureus and S. epidermidis strains. Methods: First, the antimicrobial/antibiofilm effect of Xylitol-XYL and Galacto-OligoSaccharides–GOS combined with each other at different concentrations (1, 2.5, 5%) against S. aureus and S. epidermidis clinical strains was evaluated in time. Second, the most species-specific concentration was used to combine XYL with Fructo-OligoSaccharides–FOS, IsoMalto-Oligosaccharides–IMO, ArabinoGaLactan–LAG, inulin, dextran. Experiments were performed by OD₆₀₀ detection, biomass quantification and LIVE/DEAD staining. Results: 1% XYL + 1% GOS showed the best species-specific action with an immediate antibacterial/antibiofilm action against S. aureus strains (up to 34.54% ± 5.35/64.68% ± 4.77) without a relevant effect on S. epidermidis. Among the other prebiotic formulations, 1% XYL plus 1% FOS (up to 49.17% ± 21.46/37.59% ± 6.34) or 1% IMO (up to 41.28% ± 4.88/36.70% ± 10.03) or 1% LAG (up to 38.21% ± 5.31/83.06% ± 5.11) showed antimicrobial/antibiofilm effects similar to 1% XYL+1% GOS. For all tested formulations, a prevalent bacteriostatic effect in the planktonic phase and a general reduction of S. aureus biofilm formation without loss of viability were recorded. Conclusion: The combinations of 1% XYL with 1% GOS or 1% FOS or 1% IMO or 1% LAG may help to control the balance of skin microbiota, representing good candidates for topic formulations.

Symptom assessment after nasal irrigation with xylitol in the postoperative period of endonasal endoscopic surgery

INTRODUCTION

Chronic rhinosinusitis is an inflammatory condition of the nasal cavity and the paranasal sinuses that requires multifactorial treatment. Xylitol can be employed with nasal irrigation and can provide better control of the disease.

OBJECTIVE

To evaluate the association between the effects of nasal lavage with saline solution compared to nasal lavage with a xylitol solution.

METHODS

Fifty-two patients, divided into two groups (n = 26 in the "Xylitol" group and n = 26 in the "Saline solution" group) answered questionnaires validated in Portuguese (NOSE and SNOT-22) about their nasal symptoms and general symptoms, before and after endonasal endoscopic surgery and after a period of 30 days of nasal irrigation.

RESULTS

The "Xylitol" group showed significant improvement in pain relief and nasal symptom reduction after surgery and nasal irrigation with xylitol solution (p < 0.001). The "Saline solution" group also showed symptom improvement, but on a smaller scale.

CONCLUSION

This study suggests that the xylitol solution can be useful in the postoperative period after endonasal endoscopic surgery, because it leads to a greater reduction in nasal symptoms.

Interventions to reduce Staphylococcus aureus in the management of eczema

BACKGROUND

Staphylococcus aureus (S. aureus) can cause secondary infection in eczema, and may promote inflammation in eczema that does not look infected. There is no standard intervention to reduce S. aureus burden in eczema. It is unclear whether antimicrobial treatments help eczema or promote bacterial resistance. This is an update of a 2008 Cochrane Review.

OBJECTIVES

To assess the effects of interventions to reduce S. aureus for treating eczema.

SEARCH METHODS

We updated our searches of the following databases to October 2018: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase and LILACS. We searched five trials registers and three sets of conference proceedings. We checked references of trials and reviews for further relevant studies. We contacted pharmaceutical companies regarding ongoing and unpublished trials.

SELECTION CRITERIA

Randomised controlled trials of products intended to reduce S. aureus on the skin in people diagnosed with atopic eczema by a medical practitioner. Eligible comparators were a similar treatment regimen without the anti-staphylococcal agent.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our key outcomes were participant- or assessor-rated global improvement in symptoms/signs, quality of life (QOL), severe adverse events requiring withdrawal, minor adverse events, and emergence of antibiotic-resistant micro-organisms.

MAIN RESULTS

We included 41 studies (1753 analysed participants) covering 10 treatment categories. Studies were conducted mainly in secondary care in Western Europe; North America; the Far East; and elsewhere. Twelve studies recruited children; four, adults; 19, both; and six, unclear. Fifty-nine per cent of the studies reported the mean age of participants (range: 1.1 to 34.6 years). Eczema severity ranged from mild to severe. Many studies did not report our primary outcomes. Treatment durations ranged from 10 minutes to 3 months; total study durations ranged from 15 weeks to 27 months. We considered 33 studies at high risk of bias in at least one domain. We present results for three key comparisons. All time point measurements were taken from baseline. We classed outcomes as short-term when treatment duration was less than four weeks, and long-term when treatment was given for more than four weeks. Fourteen studies evaluated topical steroid/antibiotic combinations compared to topical steroids alone (infective status: infected (two studies), not infected (four studies), unspecified (eight studies)). Topical steroid/antibiotic combinations may lead to slightly greater global improvement in good or excellent signs/symptoms than topical steroid alone at 6 to 28 days follow-up (risk ratio (RR) 1.10, 95% confidence interval (CI) 1.00 to 1.21; 224 participants; 3 studies, low-quality evidence). There is probably little or no difference between groups for QOL in children, at 14 days follow-up (mean difference (MD) -0.18, 95% CI -0.40 to 0.04; 42 participants; 1 study, moderate-quality evidence). The subsequent results for this comparison were based on very low-quality evidence, meaning we are uncertain of their validity: severe adverse events were rare (follow-up: between 6 to 28 days): both groups reported flare of dermatitis, worsening of the condition, and folliculitis (325 participants; 4 studies). There were fewer minor adverse events (e.g. flare, stinging, itch, folliculitis) in the combination group at 14 days follow-up (218 participants; 2 studies). One study reported antibiotic resistance in children at three months follow-up, with similar results between the groups (65 participants; 1 study). Four studies evaluated oral antibiotics compared to placebo (infective status: infected eczema (two studies), uninfected (one study), one study's participants had colonisation but no clinical infection). Oral antibiotics may make no difference in terms of good or excellent global improvement in infants and children at 14 to 28 days follow-up compared to placebo (RR 0.80; 95% CI 0.18 to 3.50; 75 participants; 2 studies, low-quality evidence). There is probably little or no difference between groups for QOL (in infants and children) at 14 days follow-up (MD 0.11, 95% CI -0.10 to 0.32, 45 participants, 1 study, moderate-quality evidence). The subsequent results for this comparison were based on very low-quality evidence, meaning we are uncertain of their validity: adverse events requiring treatment withdrawal between 14 to 28 days follow-up were very rare, but included eczema worsening (both groups), loose stools (antibiotic group), and Henoch-Schönlein purpura (placebo group) (4 studies, 199 participants). Minor adverse events, including nausea, vomiting, diarrhoea, and stomach and joint pains, at 28 days follow-up were also rare and generally low in both groups (1 study, 68 infants and children). Antibiotic resistance at 14 days was reported as similar in both groups (2 studies, 98 infants and children). Of five studies evaluating bleach baths compared to placebo (water) or bath emollient (infective status: uninfected (two studies), unspecified (three studies)), one reported global improvement and showed that bleach baths may make no difference when compared with placebo at one month follow-up (RR 0.78, 95% CI 0.37 to 1.63; 36 participants; low-quality evidence). One study showed there is probably little or no difference in QOL at 28 days follow-up when comparing bleach baths to placebo (MD 0.90, 95% CI -1.32 to 3.12) (80 infants and children; moderate-quality evidence). We are uncertain if the groups differ in the likelihood of treatment withdrawals due to adverse events at two months follow-up (only one dropout reported due to worsening itch (placebo group)) as the quality of evidence was very low (1 study, 42 participants). One study reported that five participants in each group experienced burning/stinging or dry skin at two months follow-up, so there may be no difference in minor adverse events between groups (RR 1.00, 95% CI 0.35 to 2.87, 36 participants, low-quality evidence). Very low-quality evidence means we are also uncertain if antibiotic resistance at four weeks follow-up is different between groups (1 study, 80 participants ≤ 18 years).

AUTHORS' CONCLUSIONS

We found insufficient evidence on the effects of anti-staphylococcal treatments for treating people with infected or uninfected eczema. Low-quality evidence, due to risk of bias, imprecise effect estimates and heterogeneity, made pooling of results difficult. Topical steroid/antibiotic combinations may be associated with possible small improvements in good or excellent signs/symptoms compared with topical steroid alone. High-quality trials evaluating efficacy, QOL, and antibiotic resistance are required.

Xylitol's Health Benefits beyond Dental Health: A Comprehensive Review

Xylitol has been widely documented to have dental health benefits, such as reducing the risk for dental caries. Here we report on other health benefits that have been investigated for xylitol. In skin, xylitol has been reported to improve barrier function and suppress the growth of potential skin pathogens. As a non-digestible carbohydrate, xylitol enters the colon where it is fermented by members of the colonic microbiota; species of the genus Anaerostipes have been reported to ferment xylitol and produce butyrate. The most common Lactobacillus and Bifidobacterium species do not appear to be able to grow on xylitol. The non-digestible but fermentable nature of xylitol also contributes to a constipation relieving effect and improved bone mineral density. Xylitol also modulates the immune system, which, together with its antimicrobial activity contribute to a reduced respiratory tract infection, sinusitis, and otitis media risk. As a low caloric sweetener, xylitol may contribute to weight management. It has been suggested that xylitol also increases satiety, but these results are not convincing yet. The benefit of xylitol on metabolic health, in addition to the benefit of the mere replacement of sucrose, remains to be determined in humans. Additional health benefits of xylitol have thus been reported and indicate further opportunities but need to be confirmed in human studies.

Terpene Derivatives as a Potential Agent against Antimicrobial Resistance (AMR) Pathogens

The evolution of antimicrobial resistance (AMR) in pathogens has prompted extensive research to find alternative therapeutics. Plants rich with natural secondary metabolites are one of the go-to reservoirs for discovery of potential resources to alleviate this problem. Terpenes and their derivatives comprising of hydrocarbons, are usually found in essential oils (EOs). They have been reported to have potent antimicrobial activity, exhibiting bacteriostatic and bactericidal effects against tested pathogens. This brief review discusses the activity of terpenes and derivatives against pathogenic bacteria, describing the potential of the activity against AMR followed by the possible mechanism exerted by each terpene class. Finally, ongoing research and possible improvisation to the usage of terpenes and terpenoids in therapeutic practice against AMR are discussed.

Beyond the physico-chemical barrier: Glycerol and xylitol markedly yet differentially alter gene expression profiles and modify signalling pathways in human epidermal keratinocytes

Polyols (e.g. glycerol, xylitol) are implicated as moisturizers of the skin and other epithelial tissues. However, we lack information about their exact cellular mechanisms and their effects on the gene expression profiles. Therefore, in this study, we aimed at investigating the effects of glycerol and xylitol on human epidermal keratinocytes. The polyols (identical osmolarities; xylitol: 0.0045%-0.45%; glycerol: 0.0027%-0.27%) did not alter cellular viability or intracellular calcium concentration. However, they exerted differential effects on the expression of certain genes and signalling pathways. Indeed, both polyols up-regulated the expression of filaggrin, loricrin, involucrin and occludin; yet, xylitol exerted somewhat more profound effects. Moreover, while both polyols stimulated the MAPK pathway, only xylitol induced the activation-dependent translocation of protein kinase Cδ, a key promoter of epidermal differentiation. Finally, in various keratinocyte inflammation models, both polyols (albeit with different efficacies) exerted anti-inflammatory effects. Taken together, these data strongly suggest that glycerol and xylitol differentially modulate expressions of multiple genes and activities of signalling pathways in epidermal keratinocytes. Thus, our findings invite clinical trials to explore the applicability and the impact of a combined glycerol-xylitol therapy in the management of various skin conditions.

Potential Anti-Inflammatory and Anti-Cancer Properties of Farnesol

Farnesol, an acyclic sesquiterpene alcohol, is predominantly found in essential oils of various plants in nature. It has been reported to exhibit anti-cancer and anti-inflammatory effects, and also alleviate allergic asthma, gliosis, and edema. In numerous tumor cell lines, farnesol can modulate various tumorigenic proteins and/or modulates diverse signal transduction cascades. It can also induce apoptosis and downregulate cell proliferation, angiogenesis, and cell survival. To exert its anti-inflammatory/anti-oncogenic effects, farnesol can modulate Ras protein and nuclear factor kappa-light-chain-enhancer of activated B cells activation to downregulate the expression of various inflammatory mediators such as cyclooxygenase-2, inducible nitric oxide synthase, tumor necrosis factor alpha, and interleukin-6. In this review, we describe the potential mechanisms of action underlying the therapeutic effects of farnesol against cancers and inflammatory disorders. Furthermore, these findings support the clinical development of farnesol as a potential pharmacological agent in clinical studies.

Phytochemicals for human disease: An update on plant-derived compounds antibacterial activity

In recent years, many studies have shown that phytochemicals exert their antibacterial activity through different mechanisms of action, such as damage to the bacterial membrane and suppression of virulence factors, including inhibition of the activity of enzymes and toxins, and bacterial biofilm formation. In this review, we summarise data from the available literature regarding the antibacterial effects of the main phytochemicals belonging to different chemical classes, alkaloids, sulfur-containing phytochemicals, terpenoids, and polyphenols. Some phytochemicals, besides having direct antimicrobial activity, showed an in vitro synergistic effect when tested in combination with conventional antibiotics, modifying antibiotic resistance. Review of the literature showed that phytochemicals represent a possible source of effective, cheap and safe antimicrobial agents, though much work must still be carried out, especially in in vivo conditions to ensure the selection of effective antimicrobial substances with low side and adverse effects.

The Microbiota of the Human Skin

The aim of this chapter is to sum up important progress in the field of human skin microbiota research that was achieved over the last years.The human skin is one of the largest and most versatile organs of the human body. Owing to its function as a protective interface between the largely sterile interior of the human body and the highly microbially contaminated outer environment, it is densely colonized with a diverse and active microbiota. This skin microbiota is of high importance for human health and well-being. It is implicated in several severe skin diseases and plays a major role in wound infections. Many less severe, but negatively perceived cosmetic skin phenomena are linked with skin microbes, too. In addition, skin microorganisms, in particular on the human hands, are crucial for the field of hygiene research. Notably, apart from being only a potential source of disease and contamination, the skin microbiota also contributes to the protective functions of the human skin in many ways. Finally, the analysis of structure and function of the human skin microbiota is interesting from a basic, evolutionary perspective on human microbe interactions.Key questions in the field of skin microbiota research deal with (a) a deeper understanding of the structure (species inventory) and function (physiology) of the healthy human skin microbiota in space and time, (b) the distinction of resident and transient skin microbiota members,

Selected Compounds Structurally Related to Acyclic Sesquiterpenoids and Their Antibacterial and Cytotoxic Activity

By implementing a common and industrially used method, 30 compounds which are structurally related to geranyl acetone, nerolidol, farnesal, farnesol and farnesyl acetate were obtained. Their antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii bacteria was investigated. Pharmacophore models were proposed based on the obtained results and 3D QSAR modelling. Cytotoxic effects against mainly human immortalised and normal cell lines of different origin (malignant melanoma MeWo, colorectal adenocarcinoma HT29, promyelocytic leukemia HL60, gingival fibroblasts HFIG, skin keratinocytes HaCaT and rat small intestine epithelium IEC6) were examined. The odour descriptions of newly synthesised compounds are given.

Comparative study of normal and sensitive skin aerobic bacterial populations

The purpose of this study was to investigate if the sensitive skin syndrome, a frequent skin disorder characterized by abnormal painful reactions to environmental factors in the absence of visible inflammatory response, could be linked to a modification in the skin bacterial population. A total of 1706 bacterial isolates was collected at the levels of the forehead, cheekbone, inner elbow, and lower area of the scapula on the skin of normal and sensitive skin syndrome-suffering volunteers of both sexes and of different ages. Among these isolates, 21 strains were randomly selected to validate in a first step the Matrix-Assisted Laser Desorption/Ionization (MALDI)-Biotyper process as an efficient identification tool at the group and genus levels, by comparison to API® strips and 16S ribosomal RNA gene sequencing identification techniques. In a second step, identification of the skin microbiota isolates by the MALDI-Biotyper tool allowed to pinpoint some differences in terms of bacterial diversity with regard to the collection area, and the volunteer's age and gender. Finally, comparison of the skin microbiota from normal and sensitive skin syndrome-suffering volunteers pointed out gender-related variations but no detectable correlation between a phylum, a genus or a dominant bacterial species and the sensitive skin phenotype. This study reveals that there is no dysbiosis of aerobic cultivable bacteria associated with the sensitive skin syndrome and further demonstrates that the MALDI-Biotyper is a powerful technique that can be efficiently employed to the study of cultivable human skin bacteria. To our knowledge, this is the first study focusing on bacteria in the sensitive skin syndrome. These results are of potential importance for pharmaceutical and cosmetic industries, which are looking for new strategies to treat this multiparametric disorder.

Sugar alcohol sweeteners as alternatives to sugar with special consideration of xylitol

INTRODUCTION

Dental caries is a diet-associated disease which continues to be a serious health problem in most industrialized and developing countries. Strategies to maximize caries prevention should automatically consider the use of sugar substitutes. It is important that public health authorities are made cognizant of the availability of new polyol-type sugar substitutes.

REVIEW SUMMARY

Clinical studies have shown that xylitol, a natural, physiologic sugar alcohol of the pentitol type, can be used as a safe and effective caries-limiting sweetener. Habitual use of xylitol-containing food and oral hygiene adjuvants has been shown to reduce the growth of dental plaque, to interfere with the growth of caries-associated bacteria, to decrease the incidence of dental caries, and to be associated with remineralization of caries lesions. Numerous public regulatory bodies have endorsed the use of xylitol as a caries-limiting agent. Other sugar alcohols that have been successfully used as sugar substitutes include D-glucitol (sorbitol), which, however, owing to its hexitol nature, normally has no strong effect on the mass and adhesiveness of bacterial plaque and on the growth of mutans streptococci. A tetritol-type alditol, erythritol, has shown potential as a non-cariogenic sugar substitute. Combinations of xylitol and erythritol may reduce the incidence of caries more effectively than either alditol alone.

CONCLUSIONS

Partial sugar substitution with polyols is an important dietary tool in the prevention of dental caries that should be used to enhance existing fluoride-based caries prevention programmes. The most effective method of conveying this information to the public is through a proper health claim for these alditols in food labelling. The present review summarizes clinical and biochemical aspects of the above three dietary polyols and emphasizes the role of sugar substitution as a potential health-promoting strategy.

Effect of xylitol and other carbon sources on Streptococcus pneumoniae biofilm formation and gene expression in vitro

Xylitol inhibits the growth of Streptococcus pneumoniae. In clinical trials, xylitol decreased the occurrence of acute otitis media in day-care children, but did not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol inhibits biofilm formation of pneumococci, and measured biofilm formation and gene expression levels of the capsule gene cpsB and two other genes: autolysin encoding gene lytA and competence gene comA in different growth media in vitro. Twenty pneumococcal isolates were grown on polystyrene plates for 18 h in test media containing 0.5% xylitol, 0.5% glucose, 0.5% xylitol and 0.5% glucose, 0.5% fructose, 0.5% xylitol and 0.5% fructose or brain heart infusion (BHI) medium supplemented with 10% horse serum. Gene expression levels were measured after 5 h of growth using a relative quantification method with calibrator normalization. Exposure to xylitol lowered OD values, which were used as an indication of biofilm, compared with BHI medium, but when the medium was supplemented with glucose or fructose, biofilm formation was enhanced and the inhibitory effect of xylitol on biofilm formation was not observed. Xylitol also lowered lytA expression levels. Changes in biofilm formation in response to different sugar compounds may partly explain the efficacy of xylitol to prevent acute otitis media in previous clinical trials.

Anti-biofilm strategies and the need for innovations in wound care

With an aging and obese population, chronic wounds such as diabetic ulcers, pressure ulcers, and venous leg ulcers are of an increasingly relevant medical concern in the developed world. Identification of bacterial biofilm contamination as a major contributor to non-healing wounds demands biofilm-targeted strategies to treat chronic wounds. While the current standard of care has proven marginally effective, there are components of standard care that should remain part of the wound treatment regime including systemic and topical antibiotics, antiseptics, and physical debridement of biofilm and devitalized tissue. Emerging anti-biofilm strategies include novel, non-invasive means of physical debridement, chemical agent strategies, and biological agent strategies. While aging and obesity will continue to be major burdens to wound care, the emergence of wounds associated with war require investigation and biotechnology development to address biofilm strategies that manage multi-drug resistant bacteria contaminating the chronic wound. The article presents some of the recent patents related to anti-biofilm strategy in wound care.

A Role of Staphyococcus aureus, Interleukin-18, Nerve Growth Factor and Semaphorin 3A, an Axon Guidance Molecule, in Pathogenesis and Treatment of Atopic Dermatitis

Staphylococcus aureus (SA) is usually present not only in the skin lesions of atopic dermatitis (AD) but also in the atopic dry skin. SA discharges various toxins and enzymes that injure the skin, results in activation of epidermal keratinocytes, which produce and release IL-18. IL-18 that induces the super Th1 cells secreting IFN-γ and IL-13 is supposed to be involved in development of AD and its pathogenesis. Indeed, the number of SA colonies on the skin surface and the serum IL-18 levels in patients with AD significantly correlated with the skin scores of AD lesions. Also, there is strong positive correlation between the skin scores and serum IL-18 levels in DS-Nh mice (P<0.0001, r=0.64), which develop considerable AD-like legions when they are housed under conventional conditions, but develop skin legions with less severity and less frequency under specific pathogens free (SPF) conditions. Therefore, they are well-known as model mice of AD, in which SA is presumed to be critical factor for the development of AD lesions. Also, theses DS-Nh mice pretreated with Cy developed more remarkable AD-like lesions in comparison with non-treated ones. The levels of INF-r and IL-13 in the supernatants of the lymph node cell cultures stimulated with staphylococcal enterotoxin B (SEB) or ConA were increased in the Cy-treated mice, although the serum levels of total IgE were not. In this experiment, we revealed that Cy-treated mice, to which CD25 +CD4 + reguratory T cells taken from non-treated ones had been transferred, developed the AD-like legions with less severity and less number of SA colonies on the skin surface. Therefore, it is presumed that CD25 +CD4 + reguratory T cells might be involved in the suppression of super Th1 cells which are induced by IL-18 and are involved in the development of AD-like lesions rather than IgE production. The efficient induction of CD25 +CD4 + reguratory T cells is expected for the new type of treatment of AD. We also found that farnesol (F) and xylitol (X) synergistically inhibited biofilm formation by SA, and indeed the ratio of SA in total bacteria at sites to which the FX cream containing F and X had been applied was significantly decreased 1 week later, accompanied with improvement of AD, when compared with that before application and at placebo sites. Therefore, the FX cream is a useful skin-care agent for atopic dry skin colonized by SA. The nerve growth factor (NGF) in the horny layer (the horn NGF) of skin lesions on the cubital fossa was collected by tape stripping and measured using ELISA in AD patients before and after 2 and 4 weeks treatments. Simultaneously, the itch and eruptions on the whole body and on the lesions, in which the horn NGF was measured, were recorded, and also the peripheral blood eosinophil count, serum LDH level and serum total IgE level were examined. The level of NGF was significantly higher in AD patients than in healthy controls, correlated with the severity of itch, erythema, scale/xerosis, the eosinophil count and LDH level, and also significantly decreased after treatments with olopatadine and/or steroid ointment for 2 and 4 weeks. Therefore, the measurement of the NGF by this harmless method seems to be useful to assess the severity of AD and the therapeutic effects on AD. In AD patients, C-fiber in the epidermis increase and sprout, inducing hypersensitivity, which is considered to aggravate the disease. Semaphorin 3A (Sema3A), an axon guidance molecule, is a potent inhibitor of neurite outgrowth of sensory neurons. We administered recombinant Sema3A intracutaneously into the skin lesions of NC/Nga mice, an animal model of AD, and investigated the effect of Sema3A on the skin lesions and their itch. Sema3A dose-dependently improved skin lesions and attenuated the scratching behavior in NC/Nga mice. Histological examinations revealed a decrease in the epidermal thickness, the density of invasive nerve fibers in the epidermis, inflammatory infiltrate including mast cells and CD4 +T cells, and the production of IL-4 in the Sema3A-treated lesions. Because the interruption of the itch-scratch cycle likely contributes to the improvement of the AD-like lesions, Sema3A is expected to become a promising treatment of patients with refractory AD.

Effects of biofilm treatments on the multi-species Lubbock chronic wound biofilm model

OBJECTIVE

To evaluate the efficacy of several biofilm effectors in inhibiting biofilm formation in an in vitro multi-species chronic wound biofilm model.

METHOD

The Lubbock Chronic Wound Biofilm (LCWB) model has been described in detail elsewhere. Pathogens used in the model are Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus. These are three of the most important species associated with biofilms. Here, the model was exposed to the following biofilm effectors: xylitol, salicylic acid, farnesol, erythritol and two proprietary, semi-solid, wound-dressing formulations currently under development (Sanguitec gels).

RESULTS

Biofilm formation was completely inhibited in the LCWB model following treatment with 20% xylitol, 10% erythritol, 1,000 microg/ml farnesol, 20mM salicylic acid or 0.1% of either of the two Sanguitec gel formulations. Salicylic acid specifically inhibited S. aureus (p<0.01) at 10mM and 20mM, consequently increasing the ratios of P. aeruginosa and E. faecalis within the biofilm. Xylitol had an increasing inhibitory effect on P. aeruginosa (p<0.01) at all concentrations evaluated. Erythritol had an inhibitory effect on P. aeruginosa and S. aureus growth (p<0.01) at over 5% concentrations. The inhibitory effect of both Sanguitec gel formulations was more broadly effective, with an increasingly inhibitory effect on all LCWB species (p<0.01).

CONCLUSION

The LCWB model provides a multi-species format with which to evaluate the effect of biofilm effectors on wound flora in a biofilm phenotype. These results suggest that different treatments can target specific populations within a biofilm. Salicylic acid preferentially targeted S. aureus, xylitol preferentially targeted P. aeruginosa, while erythritol preferentially targeted both P. aeruginosa and S. aureus. In contrast, the two Sanguitec gel formulations provided a broad, less preferential, inhibition of biofilm development.

DECLARATION OF INTEREST

Research and Testing Laboratory is a for-profit enterprise that develops molecular methods and performs service research work on biofilms. Sanguitec gel was developed by JPK and CEJ.

[Pre- and probiotic cosmetics]

The human skin provides a habitat for a variety of microorganisms, the skin microflora. There is a complex network of interactions between the microbes and cells of the epidermis. Modern analytical methods in molecular biology have revealed new insights into this complex diversity of partially unculturable microbial organisms. Most of the resident microbes on healthy skin can be regarded as being harmless or even beneficial to skin. In the case of diseases with some imbalance in microorganisms, such as impure skin/mild acne or dry skin/mild atopic dermatitis, pre- and probiotic concepts represent an effective alternative to strictly antibacterial products. Prebiotic actives rebalance the skin microflora while probiotic approaches predominantly consist of applying an inactivated microbial biomass of beneficial bacteria. Several examples of successful in vivo studies illustrate this new principle for gentle cosmetics derived from the food sector.

Bacteriophage therapy of venous leg ulcers in humans: results of a phase I safety trial

OBJECTIVE

This phase 1 trial set out to examine the safety of a bacteriophage-based preparation for difficult-to-treat wounds.

METHOD

The intention-to-treat sample comprised 42 patients with chronic venous leg ulcers (VLUs); 39 patients completed the trial. The ulcers were treated for 12 weeks with either a saline control or bacteriophages targeted against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Follow-up continued until week 24.

RESULTS

No adverse events were attributed to the study product. No significant difference (p>0.05) was determined between the test and control groups for frequency of adverse events, rate of healing, or frequency of healing.

CONCLUSION

This study found no safety concerns with the bacteriophage treatment. Efficacy of the preparation will need to be evaluated in a phase II efficacy study.

DECLARATION OF INTEREST

One of the authors (AS) holds an equity interest in Intralytix. The other authors do not have any interest in commercial activities.

Biofilms in wounds: management strategies

Biofilms probably induce a chronic and/or 'quiet' inflammation in the chronic wound and so delay healing. This paper reviews current strategies that can be used to suppress biofilms in chronic wounds until better options are available.

Interventions to reduce Staphylococcus aureus in the management of atopic eczema

BACKGROUND

Staphylococcus aureus can cause secondary infection in atopic eczema, and it may promote inflammation in eczema that does not look infected. Many antimicrobial products exist for eczema, but it is unclear if they work or if they promote bacterial resistance.

OBJECTIVES

To assess the effects of interventions to reduce Staphylococcus aureus for treating infected or uninfected atopic eczema.

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (March 2008), the Cochrane Central Register of Controlled Trials (Cochrane Library Issue 1, 2008), MEDLINE (OVID) (from 2002 to March 2008), EMBASE (OVID) (from 2002 to March 2008), Ongoing trials registers (March 2008). References from trials and reviews were searched, pharmaceutical companies were contacted for unpublished trials. There were no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of people with atopic eczema who have been treated with a product intended to reduce S. aureus on the skin.

DATA COLLECTION AND ANALYSIS

Two people independently performed the study selection, data abstraction and quality assessment.

MAIN RESULTS

We included 21 studies (1018 participants) covering 7 treatment categories. Most studies were poorly reported and study differences limited pooling of results. Adverse effects were especially poorly reported, and only one study reported the emergence of resistant bacterial strains following oral antibiotics. Oral antibiotics were not associated with benefit in non-infected (2 trials, 66 participants) or infected eczema (1 trial, 33 participants). We did not find any benefit for antibacterial soaps (1 trial, 50 participants), or antibacterial bath additives (2 trials, 41 participants), or topical antibiotics/antiseptics (4 studies, 95 participants). Adding antibiotics to topical corticosteroids reduced numbers of Staphylococcus aureus in 4 trials (302 participants), but there was no evidence of any clinical benefit in 9 trials involving 677 participants: betamethasone plus neomycin vs clobetasol (MD 1.2; 95% CI 0.25, 2.15), prednicarbate plus antimicrobial vs prednicarbate (RR 0.64; 95% CI 0.25, 1.68), or betamethasone valerate plus gentamicin vs betamethasone (RR 0.31; 95% CI 0.07, 1.35). One trial (30 participants) showed no significant improvement in eczema for those using silver textiles (RR 2.67; 95% CI 0.98, 7.22), despite using 10 times the amount of topical steroids.

AUTHORS' CONCLUSIONS

We failed to find clear evidence of benefit for antimicrobial interventions for people with atopic eczema, despite their widespread use. This does not necessarily mean they do not work because the studies were small and poorly reported. Further large studies with long-term outcomes and clearly defined participants are urgently required.

A study of biofilm-based wound management in subjects with critical limb ischaemia

OBJECTIVE

Bacterial biofilms cause or complicate numerous medical conditions, including chronic wounds. Biofilm-based wound care (BBWC) management strategies that suppress biofilm have been designed and are used extensively at the Southwest Regional Wound Care Center in Lubbock, Texas and are described in this article. This retrospective single-centre study was designed to evaluate the frequency of complete healing in subjects with a chronic wound in a limb with critical limb ischaemia (CLI) when managed using BBWC.

METHOD

Of the 4500 subjects admitted with wounds between August 2002 and January 2006, 1400 subjects' TCpO2 levels were measured, and 266 included were identified as having CLI (TCpO2 < 20mmHg). Of these, 190 subjects were considered in the analysis because they received a substantial course of therapy (more than five visits). Each subject was individually managed to reinforce natural healing and suppress bacterial biofilm. Successful healing was defined as complete closure by March 2007.

RESULTS

Of the 190 subjects with CLI, 146 (77%) healed completely, and 44 (23%) were categorised as non-healing. The healed group included 47% (68/146) with osteomyelitis and 69% (101/146) with diabetes mellitus. In the non-healed group, 75% (33/44) had osteomyelitis and 77% (34/44) had diabetes mellitus. Ninety-one per cent (30/33) of the subjects without osteomyelitis or diabetes mellitus healed, and 67% (53/79) of the subjects with both osteomyelitis and diabetes mellitus healed.

CONCLUSION

When comparing the healing frequency in this study with a previously published study, BBWC strategies significantly improved healing frequency. These findings demonstrate that effectively managing the biofilm in chronic wounds is an important component of consistently transforming 'non-healable' wounds into healable wounds.

Sesquiterpene farnesol as a competitive inhibitor of lipase activity ofStaphylococcus aureus

Staphylococcus aureus lipase (SAL) is known to possess broad substrate specificity for triacylglycerides. We found that a sub-minimum inhibitory concentration of farnesol (1000 mg L(-1)) inhibits this lipase activity on a Mueller-Hinton agar containing 1% Tween substrates. A quantitative lipase assay using p-nitrophenyl palmitate (pNPP) revealed that the inhibitory action of farnesol appears to be the result of the inhibition of lipase activity rather than of its secretion into the culture medium. The inhibition was observed in all the tested 8 methicillin-susceptible S. aureus and 31 methicillin-resistant S. aureus clinical isolates. Using homogeneous lipase purified by hydrophobic interaction chromatography, it was revealed that farnesol could competitively inhibit the lipase activity against the substrate pNPP.

Sesquiterpene farnesol inhibits recycling of the C55 lipid carrier of the murein monomer precursor contributing to increased susceptibility to β-lactams in methicillin-resistant Staphylococcus aureus

BACKGROUND AND OBJECTIVES

The sesquiterpene farnesol, a natural plant metabolite, is known to intensify the effect of antimicrobial agents. However, the mode of action of its antimicrobial synergism has remained poorly understood. In this study, we investigated farnesol's synergistic effects on commonly used antimicrobials, beta-lactams in particular, to explore its potential inhibitory effect on cell wall synthesis.

METHODS

We investigated farnesol's effects on: (i) antimicrobial susceptibilities of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) to ampicillin, oxacillin, cefoxitin, bacitracin, teicoplanin, amikacin, ciprofloxacin and clarithromycin by MIC determination using the Etest; (ii) penicillin-binding protein PBP2' (2a) expression by western-blot analysis; (iii) beta-lactamase secretion and activity by in vivo and in vitro farnesol inhibition assays; (iv) staphyloxanthin production by thin-layer chromatography (TLC); and (v) cell wall synthesis by [14C]GlcNAc (where GlcNAc stands for N-acetylglucosamine) and [14C]mevalonate incorporation assays, and TLC-based lipid extract profile analysis.

RESULTS

Farnesol induced variable degrees of increased susceptibility to all antimicrobials except clarithromycin in both MSSA and MRSA. A remarkable increase in susceptibilities to ampicillin, oxacillin and cefoxitin was observed in both MRSA strains, N315 and COL, whereas a moderate increase in susceptibility to bacitracin was observed in all the strains. Although no apparent suppression of PBP2' expression was observed, beta-lactamase secretion and beta-lactamase activity were significantly reduced by farnesol. In addition, farnesol completely suppressed staphyloxanthin production. Farnesol reduced the incorporation of GlcNAc, but significantly increased that of mevalonate. Farnesol induced accumulation of C55-PP, lipid I and lipid II.

CONCLUSIONS

Farnesol increased beta-lactam susceptibility of MRSA by inhibition of cell wall biosynthesis through reduction of free C55 lipid carrier with subsequent retardation of murein monomer precursor transport across the cell membrane.