The human skin microbiome

Development of humanized mouse and rat models with full-thickness human skin and autologous immune cells

The human skin is a significant barrier for protection against pathogen transmission. Rodent models used to investigate human-specific pathogens that target the skin are generated by introducing human skin grafts to immunocompromised rodent strains. Infection-induced immunopathogenesis has been separately studied in humanized rodent models developed with human lymphoid tissue and hematopoietic stem cell transplants. Successful co-engraftment of human skin, autologous lymphoid tissues, and autologous immune cells in a rodent model has not yet been achieved, though it could provide a means of studying the human immune response to infection in the human skin. Here, we introduce the human Skin and Immune System (hSIS)-humanized NOD-scid IL2Rγ^null (NSG) mouse and Sprague–Dawley-Rag2^tm2hera Il2rγ^tm1hera (SRG) rat models, co-engrafted with human full-thickness fetal skin, autologous fetal lymphoid tissues, and autologous fetal liver-derived hematopoietic stem cells. hSIS-humanized rodents demonstrate the development of human full-thickness skin, along with autologous lymphoid tissues, and autologous immune cells. These models also support human skin infection following intradermal inoculation with community-associated methicillin-resistant Staphylococcus aureus. The co-engraftment of these human skin and immune system components into a single humanized rodent model could provide a platform for studying human skin infections.

Skin Microbiome and its Interplay with the Environment

Advances in sequencing, bioinformatics and analytics now allow the structure, function and interrelations of whole microbial communities to be studied in greater detail. Collaborative efforts and multidisciplinary studies, crossing the boundary between environmental and medical microbiology, have allowed specific environmental, animal and human microbiomes to be characterized. One of the main challenges for microbial ecology is to link the phylogenetic diversity of host-associated microbes to their functional roles within the community. Much remains to be learned on the way microbes colonize the skin of different living organisms and the way the skin microbiome reacts to the surrounding environment (air, water, etc.). In this review, we discuss examples of recent studies that have used modern technology to provide insights into microbial communities in water and on skin, such as those in natural resources (thermal spring water), large mammals (humpback whales) and humans (the skin microbiome). The results of these studies demonstrate how a greater understanding of the structure and functioning of microbiota, together with their interactions with the environment, may facilitate the discovery of new probiotics or postbiotics, provide indicators for the quality of the environment, and show how changes in lifestyle and living environment, such as urbanization, can impact on the skin microbiome and skin health and disease in humans.

Lactoferrin-Derived Peptides as a Control Strategy against Skinborne Staphylococcal Biofilms

Coagulase-negative staphylococci (CoNS) widely colonize the human skin and play an active role in host defense. However, these bacteria may cause malodours and increase infection incidence rate in immune-compromised patients and individuals with catheters and implants. CoNS spreading is favored by biofilm formation that also promotes the release of virulence factors and drug resistance. Biofilm control or eradication by antimicrobial peptides (AMPs) represents an attractive strategy which is worth investigating. In this work, bovine lactoferrin (BLF) hydrolysate (HLF) was in vitro evaluated for its antimicrobial and antibiofilm activities against skin-related coagulase negative and positive staphylococci. Despite a minimal inhibitory concentration (MIC) recorded for HLF ranging from 10 to more than 20 mg/mL, a minimal biofilm inhibitory concentration (MIBC) equal to 2.5 mg/mL was found for most target strains. Conversely, MIBC values referred to the individual peptides, LFcinB or LFmpin (herein purified and identified) were significantly lower. Finally, the application of 2.5 mg/mL HLF solution by dipping and spraying on biofilm-attached glass surfaces also caused a high biofilm eradication rate depending on the incubation time, thus attracting interest for future applications in cosmetic formulation for skin care.

Cutibacterium acnes: a threat to shoulder surgery or an orthopedic red herring?

Cutibacterium acnes is a lipophilic, anaerobic, gram-positive bacillus that mainly colonizes the pilosebaceous glands of human skin. It has been implicated as the leading cause of prosthetic joint infection (PJI) after shoulder arthroplasty. However, PJI caused by C acnes rarely manifests as overt clinical, laboratory, or imaging features. In fact, more than 40% of shoulders undergoing revision arthroplasty are likely to be culture positive. However, rates of infection following a positive culture can be as low as 5%. The purpose of this review was to put forth alternative explanations for this discordance between positive cultures and infection. We describe C acnes roles as a commensal, bystander, and/or contaminant organism; the role of cultures in diagnosis and other methods that may be more accurate; its existence in a shoulder microbiome; and the variable virulence of C acnes. C acnes is an important cause of shoulder PJI in some patients. However, there is a large body of literature that suggests other functions that need to be considered. Further research is needed to define the role of C acnes that is logically explained by all of the literature and not only some.

Challenges in Human Skin Microbial Profiling for Forensic Science: A Review

The human microbiome is comprised of the microbes that live on and within an individual, as well as immediately surrounding them. Microbial profiling may have forensic utility in the identification or association of individuals with criminal activities, using microbial signatures derived from a personal microbiome. This review highlights some important aspects of recent studies, many of which have revealed issues involving the effect of contamination of microbial samples from both technical and environmental sources and their impacts on microbiome research and the potential forensic applications of microbial profiling. It is imperative that these challenges be discussed and evaluated within a forensic context to better understand the future directions and potential applications of microbial profiling for human identification. It is necessary that the limitations identified be resolved prior to the adoption of microbial profiling, or, at a minimum, acknowledged by those applying this new approach.

Dalbavancin exposure in vitro selects for dalbavancin-non-susceptible and vancomycin-intermediate strains of methicillin-resistant Staphylococcus aureus

OBJECTIVES

Dalbavancin is a lipoglycopeptide active against methicillin-resistant Staphylococcus aureus (MRSA). Its long half-life (8.5-16 days) allows for once-weekly or single-dose treatments but could prolong the mutant selection window, promoting resistance and cross-resistance to related antimicrobials such as vancomycin. The objective of this study was to evaluate the capacity of post-distributional pharmacokinetic exposures of dalbavancin to select for resistance and cross-resistance in MRSA.

METHODS

We simulated average, post-distributional exposures of single-dose (1500 mg) dalbavancin (fCmax 9.9 μg/mL, β-elimination t_1/2 204 h) in an in vitro pharmacokinetic/pharmacodynamic (PK/PD) model for 28 days (672 h) against five MRSA strains and one methicillin-susceptible strain (MSSA). Samples were collected at least daily, and surviving colonies were enumerated and screened for resistance on drug-free and dalbavancin-supplemented medium respectively. Isolates from resistance screening plates were subjected to whole-genome sequencing (WGS) and susceptibly testing against dalbavancin, vancomycin, daptomycin, and six β-lactams with varying penicillin-binding protein (PBP) affinities.

RESULTS

Dalbavancin was bactericidal against most strains for days 1-4 before regrowth of less susceptible subpopulations occurred. Isolates with eight-fold increases in dalbavancin MIC were detected as early as day 4 but increased 64-128-fold in all models by day 28. Vancomycin and daptomycin MICs increased 4-16-fold, exceeding the susceptibly breakpoints for both antibiotics; β-lactam MICs generally decreased by two-to eight-fold, suggesting a dalbavancin-β-lactam seesaw effect, but increased by eight-fold or more in certain isolates. Resistant isolates carried mutations in a variety of genes, most commonly walKR, apt, stp1, and atl.

CONCLUSIONS

In our in vitro system, post-distributional dalbavancin exposures selected for stable mutants with reduced susceptibility to dalbavancin, vancomycin, and daptomycin, and generally increased susceptibility to β-lactams in all strains of MRSA tested. The clinical significance of these findings remains unclear, but created an opportunity to genotype a unique collection of dalbavancin-resistant strains for the first time. Mutations involved genes previously associated with vancomycin intermediate susceptibility and daptomycin non-susceptibility, most commonly walKR-associated genes.

Photodynamic Activity of Tribenzoporphyrazines with Bulky Periphery against Wound Bacteria

Magnesium(II) tribenzoporphyrazines with phenoxybutylsulfanyl substituents were evaluated as photosensitizers in terms of their optical properties against wound bacteria. In the UV-vis spectra of analyzed tribenzoporphyrazines, typical absorption ranges were found. However, the emission properties were very weak, with fluorescence quantum yields in the range of only 0.002–0.051. What is important, they revealed moderate abilities to form singlet oxygen with the quantum yields up to 0.27. Under irradiation, the macrocycles decomposed via photobleaching mechanism with the quantum yields up to 8.64 × 10⁻⁵. The photokilling potential of tribenzoporphyrazines was assessed against Streptococcus pyogenes, Staphylococcus epidermidis, as well as various strains of Staphylococcus aureus, including methicillin-sensitive and-resistant bacteria. Both evaluated photosensitizers revealed high photodynamic potential against studied bacteria (>3 logs). S.aureus growth was reduced by over 5.9 log, methicillin-resistant S. aureus by 5.1 log, S.epidermidis by over 5.7 log, and S. pyogenes by over 4.7 log.

The Pathogenesis of Systemic Sclerosis: An Understanding Based on a Common Pathologic Cascade across Multiple Organs and Additional Organ-Specific Pathologies

Systemic sclerosis (SSc) is a multisystem autoimmune and vascular disease resulting in fibrosis of various organs with unknown etiology. Accumulating evidence suggests that a common pathologic cascade across multiple organs and additional organ-specific pathologies underpin SSc development. The common pathologic cascade starts with vascular injury due to autoimmune attacks and unknown environmental factors. After that, dysregulated angiogenesis and defective vasculogenesis promote vascular structural abnormalities, such as capillary loss and arteriolar stenosis, while aberrantly activated endothelial cells facilitate the infiltration of circulating immune cells into perivascular areas of various organs. Arteriolar stenosis directly causes pulmonary arterial hypertension, scleroderma renal crisis and digital ulcers. Chronic inflammation persistently activates interstitial fibroblasts, leading to the irreversible fibrosis of multiple organs. The common pathologic cascade interacts with a variety of modifying factors in each organ, such as keratinocytes and adipocytes in the skin, esophageal stratified squamous epithelia and myenteric nerve system in gastrointestinal tract, vasospasm of arterioles in the heart and kidney, and microaspiration of gastric content in the lung. To better understand SSc pathogenesis and develop new disease-modifying therapies, it is quite important to understand the complex pathogenesis of SSc from the two distinct perspectives, namely the common pathologic cascade and additional organ-specific pathologies.

Changes in the Diversity of Human Skin Microbiota to Cosmetic Serum Containing Prebiotics: Results from a Randomized Controlled Trial

Prebiotic treatment may rebalance the skin microbiota by regulating the growth of harmful and beneficial microorganisms. In this randomized, double-blind, placebo-controlled clinical trial (N = 60), we evaluated the effects of a cosmetic serum containing galacto-oligosaccharides (GOS) on the balance of the skin microbiota by measuring various skin parameters. The skin water-holding capacity between the control (ND) and experimental (NF) groups was significantly different after 8 weeks of serum treatment (p < 0.05). Similarly, changes in transepidermal water loss (TEWL) and the erythema index in the ND and NF groups were significantly different (p < 0.05). Furthermore, the wrinkle depth and Staphylococcus aureus population decreased in the NF group compared with those in the ND group (p < 0.05). The mean form factor, Shannon index, and Pediococcus population were significantly increased in the post-NF group compared with those in the post-ND group (p < 0.05). Finally, in the ND group, water-holding capacity was positively correlated with Enhydrobacter, whereas Enterobacteriaceae was negatively correlated with TEWL in the NF group. These results suggest that GOS inhibit the growth of harmful skin microbes and increase the population of beneficial microbes.

Gut microbiome and human health under the space environment

The gut microbiome is well recognized to have a pivotal role in regulation of the health and behaviour of the host, affecting digestion, metabolism, immunity, and has been linked to changes in bones, muscles and the brain, to name a few. However, the impact of microgravity environment on gut bacteria is not well understood. In space environments, astronauts face several health issues including stress, high iron diet, radiation and being in a closed system during extended space missions. Herein, we discuss the role of gut bacteria in the space environment, in relation to factors such as microgravity, radiation and diet. Gut bacteria may exact their effects by synthesis of molecules, their absorption, and through physiological effects on the host. Moreover we deliberate the role of these challenges in the dysbiosis of the human microbiota and possible dysregulation of the immune system.

Characterization of Cutaneous Bacterial Microbiota from Superficial Pyoderma Forms in Atopic Dogs

Although Staphylococcus pseudintermedius is considered the major pathogen associated with superficial canine pyoderma, no study has investigated the entire bacterial community in these lesions with molecular techniques. The objectives of this study were to characterize the bacterial microbiota in two forms of superficial canine pyoderma lesions, superficial bacterial folliculitis (SBF) and epidermal collarette (EC), especially in terms of the staphylococcal community. Swabs from 12 SBF and 9 EC lesions were obtained from eight and six atopic dogs, respectively. Eight samples from the axilla and groin of four healthy dogs served as controls. DNA was extracted for 16S rRNA gene sequencing and quantitative polymerase chain reaction of Staphylococcus spp. and S. pseudintermedius. Healthy skin samples harbored significantly more diverse bacterial communities than pyoderma samples. Healthy samples had communities that were more similar to each other, and were distinct from pyoderma samples. Staphylococcus spp. abundance was increased in pyoderma samples, especially those from EC samples. Although determining species-level identities of staphylococcal sequences revealed many species, S. pseudintermedius was the primary staphylococcal species found in all sample types. As expected, there are many differences in the microbiota when comparing healthy and canine pyoderma lesions samples. These lesions do not seem to be associated with a change in the relative abundance of specific Staphylococcus species, but simply an overall increase in Staphylococcus spp. abundance. The results of this study provide a starting point for future studies investigating how antimicrobial treatments may further change the microbiota associated with these lesions.

From Food Waste to Innovative Biomaterial: Sea Urchin-Derived Collagen for Applications in Skin Regenerative Medicine

Collagen-based skin-like scaffolds (CBSS) are promising alternatives to skin grafts to repair wounds and injuries. In this work, we propose that the common marine invertebrate sea urchin represents a promising and eco-friendly source of native collagen to develop innovative CBSS for skin injury treatment. Sea urchin food waste after gonad removal was here used to extract fibrillar glycosaminoglycan (GAG)-rich collagen to produce bilayer (2D + 3D) CBSS. Microstructure, mechanical stability, permeability to water and proteins, ability to exclude bacteria and act as scaffolding for fibroblasts were evaluated. Our data show that the thin and dense 2D collagen membrane strongly reduces water evaporation (less than 5% of water passes through the membrane after 7 days) and protein diffusion (less than 2% of BSA passes after 7 days), and acts as a barrier against bacterial infiltration (more than 99% of the different tested bacterial species is retained by the 2D collagen membrane up to 48 h), thus functionally mimicking the epidermal layer. The thick sponge-like 3D collagen scaffold, structurally and functionally resembling the dermal layer, is mechanically stable in wet conditions, biocompatible in vitro (seeded fibroblasts are viable and proliferate), and efficiently acts as a scaffold for fibroblast infiltration. Thus, thanks to their chemical and biological properties, CBSS derived from sea urchins might represent a promising, eco-friendly, and economically sustainable biomaterial for tissue regenerative medicine.

Influences of claywater and greenwater on the skin microbiome of cultured larval sablefish (Anoplopoma fimbria)

Background

The skin microbiome of marine fish is thought to come from bacteria in the surrounding water during the larval stages, although it is not clear how different water conditions affect the microbial communities in the water and, in turn, the composition and development of the larval skin microbiome. In aquaculture, water conditions are especially important; claywater and greenwater are often used in larval rearing tanks to increase water turbidity. Here, we explored the effects of these water additives on microbial communities in rearing water and on the skin of first-feeding sablefish larvae using 16S rRNA gene sequencing. We evaluated three treatments: greenwater, claywater, and greenwater with a switch to claywater after 1 week.

Results

We observed additive-specific effects on rearing water microbial communities that coincided with the addition of larvae and rotifer feed to the tanks, such as an increase in Vibrionaceae in greenwater tanks. Additionally, microbial communities from experimental tank water, especially those in claywater, began to resemble larval skin microbiomes by the end of the experiment. The differential effects of the additives on larval sablefish skin microbiomes were largest during the first week, post-first feed. Bacteria associated with greenwater, including Vibrionaceae and Pseudoalteromonas spp., were found on larval skin a week after the switch to claywater. In addition to additive-specific effects, larval skin microbiomes also retained bacterial families likely acquired from their hatchery silos.

Conclusions

Our results suggest that larval sablefish skin microbiomes are most sensitive to the surrounding seawater up to 1 week following the yolk-sac stage and that claywater substituted for greenwater after 1 week post-first feed does not significantly impact skin-associated microbial communities. However, the larval skin microbiome changes over time under all experimental conditions. Furthermore, our findings suggest a potential two-way interaction between microbial communities on the host and the surrounding environment. To our knowledge, this is one of the few studies to suggest that fish might influence the microbial community of the seawater.

Pseudonajide peptide derived from snake venom alters cell envelope integrity interfering on biofilm formation in Staphylococcus epidermidis

Background

The increase in bacterial resistance phenotype cases is a global health problem. New strategies must be explored by the scientific community in order to create new treatment alternatives. Animal venoms are a good source for antimicrobial peptides (AMPs), which are excellent candidates for new antimicrobial drug development. Cathelicidin-related antimicrobial peptides (CRAMPs) from snake venoms have been studied as a model for the design of new antimicrobial pharmaceuticals against bacterial infections.

Results

In this study we present an 11 amino acid-long peptide, named pseudonajide, which is derived from a Pseudonaja textilis venom peptide and has antimicrobial and antibiofilm activity against Staphylococcus epidermidis. Pseudonajide was selected based on the sequence alignments of various snake venom peptides that displayed activity against bacteria. Antibiofilm activity assays with pseudonajide concentrations ranging from 3.12 to 100 μM showed that the lowest concentration to inhibit biofilm formation was 25 μM. Microscopy analysis demonstrated that pseudonajide interacts with the bacterial cell envelope, disrupting the cell walls and membranes, leading to morphological defects in prokaryotes.

Conclusions

Our results suggest that pseudonajide’s positives charges interact with negatively charged cell wall components of S. epidermidis, leading to cell damage and inhibiting biofilm formation.

Dialog between skin and its microbiota: Emergence of "Cutaneous Bacterial Endocrinology"

Microbial endocrinology is studying the response of microorganisms to hormones and neurohormones and the microbiota production of hormones-like molecules. Until now, it was mainly applied to the gut and revealed that the intestinal microbiota should be considered as a real organ in constant and bilateral interactions with the whole human body. The skin harbours the second most abundant microbiome and contains an abundance of nerve terminals and capillaries, which in addition to keratinocytes, fibroblasts, melanocytes, dendritic cells and endothelial cells, release a huge diversity of hormones and neurohormones. In the present review, we will examine recent experimental data showing that, in skin, molecules such as substance P, calcitonin gene-related peptide, natriuretic peptides and catecholamines can directly affect the physiology and virulence of common skin-associated bacteria. Conversely, bacteria are able to synthesize and release compounds including histamine, glutamate and γ-aminobutyric acid or peptides showing partial homology with neurohormones such as α-melanocyte-stimulating hormone (αMSH). The more surprising is that some viruses can also encode neurohormones mimicking proteins. Taken together, these elements demonstrate that there is also a cutaneous microbial endocrinology and this emerging concept will certainly have important consequences in dermatology.

[Rational strategy for studying microbiome of the ocular surface of people using hard contact lenses by method of 16S rRNA gene metabarcoding]

The study is based on the hypothesis that high taxonomic diversity of bacteria detectable on the eye surface by molecular genetic methods is attributed to the high level of its contamination by skin microflora. Such contamination would make it problematic to identify the fractions of real ocular surface microbiome, which remains behind the one-percent cut-off threshold adopted in the metagenomic analysis. Hard contact lenses for long-wearing act as a physical filter preventing DNA contamination from random microorganisms, and at the same time providing adhesion to the living cells of bacteria and fungi. To confirm this assumption, a detailed analysis of references was carried out, supplemented by original laboratory research.

MATERIAL AND METHODS

The analysis included 16 hard contact lenses obtained from 11 patients with impaired refraction (myopia). Additionally, conjunctival mucosa scrapings were collected from 42 patients. Samples were cross-analyzed by 16S rRNA gene sequencing using 454 GS Junior (Ion Torrent) and Illumina MiSeq platforms.

RESULTS

Results obtained by the Illumina platform (analysis of the V3-V4 variable region of the 16S rRNA gene) showed better convergence with the data of culture tests reported in the literature. The major microorganism groups found were: Acinetobacter (39%), Gluconacetobacter (10.8%), Propionibacterium (9.3%), Corynebacterium (9.3%), Staphylococcus (7.2%), Streptococcus (7%), Pseudomonas (4.1%), Micrococcus (3.3%), Yersinia (3%), Chondromyces (2.4%), Serratia (2.3%), and Bacillus (2.1%). Analysis of the samples obtained directly from the mucosa revealed dominance of typical skin-associated microorganisms.

CONCLUSION

The present study proposes a contamination-reduction algorithm for microbiological testing of the ocular surface using hard contact lenses for prolonged wearing as a carrier for microbial DNA.

Corneotherapie – Pflege und Reparatur der Haut: präzise, effektiv und nachhaltig

Die Pflege und Gesunderhaltung der Haut ist nicht nur für ein gutes Aussehen, sondern auch für das allgemeine Wohlbefinden essenziell. Viele Menschen investieren daher für die Hautpflege nicht nur viel Zeit, sondern auch viel Geld. Oft stellt sich jedoch die Frage, welche Produkte aus der Vielfalt an Angeboten nun besonders effektiv und empfehlenswert sind. Der Artikel gibt darüber Auskunft. Er erläutert die Grundlagen und aktuellen Erkenntnisse der Corneobiologie und zeigt, wie eine präzise, effektive und nachhaltige Hautpflege heute aussehen sollte.

Surface Proteins of Staphylococcus epidermidis

Staphylococcus epidermidis is a ubiquitous commensal of human skin. The widespread use of indwelling medical devices in modern medicine provides an opportunity for it to cause infections. Disease causing isolates can come from many different genetic backgrounds. Multiply antibiotic resistant strains have spread globally. S. epidermidis has a smaller repertoire of cell wall anchored (CWA) surface proteins than Staphylococcus aureus. Nevertheless, these CWA proteins promote adhesion to components of the extracellular matrix including collagen, fibrinogen, and fibronectin and contribute to the formation of biofilm. The A domain of the accumulation associated protein Aap can promote adhesion to unconditioned biomaterial but must be removed proteolytically to allow accumulation to proceed by homophilic Zn²⁺-dependent interactions. Mature biofilm contains amyloid structures formed by Aap and the small basic protein (Sbp). The latter contributes to the integrity of both protein and polysaccharide biofilm matrices. Several other CWA proteins can also promote S. epidermidis biofilm formation.

Dynamics of Skin Mycobiome in Infants

Understanding the microbial community structure of the human skin is important for treating cutaneous diseases; however, little is known regarding skin fungal communities (mycobiomes). The aim of the present study was to investigate the features of and variations in skin fungal communities during infancy in 110 subjects less than 6 months of age. Skin samples were obtained from the back, antecubital fossa, and volar forearm, while physiological parameters including transepidermal water loss, pH, surface moisture, and deep layer hydration were evaluated. Skin fungal diversity decreased after the first three months of life. Differences in fungal community composition were greater among individual infants than among the three skin sites in the same individual. Inter- and intra-individual variation were similar and lower, respectively, than the variability between two samples obtained 12 weeks apart, from the same site in the same subject, suggesting low stability of fungal communities on infant skin. Skin physiological parameters showed little correlation with skin fungal community structure. Additionally, Malassezia was the most represented genus (36.43%) and M. globosa was the most abundant species in Malassezia with its abundance decreasing from 54.06% at 0–2 months to 34.54% at 5–6 months. These findings provide a basis for investigating the causative fungi-skin interactions associated with skin diseases.

Characterization of skin surface and dermal microbiota in dogs with mast cell tumor

The skin microbiota interacts with the host immune response to maintain the homeostasis. Changes in the skin microbiota are linked to the onset and the progression of several diseases, including tumors. We characterized the skin surface and dermal microbiota of 11 dogs affected by spontaneous mast cell tumor (MCT), using skin contralateral sites as intra-animal healthy controls. The microbial profile differed between healthy and tumor skin surfaces and dermis, demonstrating that the change in microbiota composition is related to the presence of MCT. The number of observed taxa between MCT and healthy skin surfaces was detected, showing a decrease in number and heterogeneity of taxa over the skin surface of MCT, at both inter- and intra-individual level. Preliminary data on bacterial population of MCT dermis, obtained only on three dogs, demonstrated an intra-individual reduction of taxa number when compared to the skin surface. Taxonomy reveals an increase of Firmicutes phylum and Corynebacteriaceae family in MCT skin surface when compared to the healthy contralateral. In conclusion, we demonstrate that microbial population of skin surface and dermis is related to mast cell tumor. Our study provides the basis for future investigations aiming to better define the interaction between mast cell tumors, microbiota and host immune response.

Untangling Species-Level Composition of Complex Bacterial Communities through a Novel Metagenomic Approach

16S small-subunit (SSU) rRNA gene-based bacterial profiling is the gold standard for cost-effective taxonomic reconstruction of complex bacterial populations down to the genus level. However, it has been proven ineffective in clinical and research settings requiring higher taxonomic resolution. We therefore developed a bacterial profiling method based on the internal transcribed spacer (ITS) region employing optimized primers and a comprehensive ITS database for accurate cataloguing of bacterial communities at (sub)species resolution. Performance of the microbial ITS profiling pipeline was tested through analysis of host-associated, food, and environmental matrices, while its efficacy in clinical settings was assessed through analysis of mucosal biopsy specimens of colorectal cancer, leading to the identification of putative novel biomarkers. The data collected indicate that the proposed pipeline represents a major step forward in cost-effective identification and screening of microbial biomarkers at (sub)species level, with relevant impact in research, industrial, and clinical settings.IMPORTANCE We developed a novel method for accurate cataloguing of bacterial communities at (sub)species level involving amplification of the internal transcribed spacer (ITS) region through optimized primers, followed by next-generation sequencing and taxonomic classification of amplicons by means of a comprehensive database of bacterial ITS sequences. Host-associated, food, and environmental matrices were employed to test the performance of the microbial ITS profiling pipeline. Moreover, mucosal biopsy samples from colorectal cancer patients were analyzed to demonstrate the scientific relevance of this profiling approach in a clinical setting through identification of putative novel biomarkers. The results indicate that the ITS-based profiling pipeline proposed here represents a key metagenomic tool with major relevance for research, industrial, and clinical settings.

Impact of airborne particulate matter on skin: a systematic review from epidemiology to in vitro studies

BACKGROUND

Air pollution is killing close to 5 million people a year, and harming billions more. Air pollution levels remain extremely high in many parts of the world, and air pollution-associated premature deaths have been reported for urbanized areas, particularly linked to the presence of airborne nano-sized and ultrafine particles.

MAIN TEXT

To date, most of the research studies did focus on the adverse effects of air pollution on the human cardiovascular and respiratory systems. Although the skin is in direct contact with air pollutants, their damaging effects on the skin are still under investigation. Epidemiological data suggested a correlation between exposure to air pollutants and aggravation of symptoms of chronic immunological skin diseases. In this study, a systematic literature review was conducted to understand the current knowledge on the effects of airborne particulate matter on human skin. It aims at providing a deeper understanding of the interactions between air pollutants and skin to further assess their potential risks for human health.

CONCLUSION

Particulate matter was shown to induce a skin barrier dysfunction and provoke the formation of reactive oxygen species through direct and indirect mechanisms, leading to oxidative stress and induced activation of the inflammatory cascade in human skin. Moreover, a positive correlation was reported between extrinsic aging and atopic eczema relative risk with increasing particulate matter exposure.

Staphylococcus saccharolyticus: An Overlooked Human Skin Colonizer

Coagulase-negative staphylococcal species constitute an important part of the human skin microbiota. In particular, facultative anaerobic species such as Staphylococcus epidermidis and Staphylococcus capitis can be found on the skin of virtually every human being. Here, we applied a culture-independent amplicon sequencing approach to identify staphylococcal species on the skin of healthy human individuals. While S. epidermidis and S. capitis were found as primary residents of back skin, surprisingly, the third most abundant member was Staphylococcus saccharolyticus, a relatively unstudied species. A search of skin metagenomic datasets detected sequences identical to the genome of S. saccharolyticus in diverse skin sites, including the back, forehead, and elbow pit. Although described as a slow-growing anaerobic species, a re-evaluation of its growth behavior showed that S. saccharolyticus can grow under oxic conditions, and, in particular, in a CO₂-rich atmosphere. We argue here that S. saccharolyticus was largely overlooked in previous culture-dependent and -independent studies, due to its requirement for fastidious growth conditions and the lack of reference genome sequences, respectively. Future studies are needed to unravel the microbiology and host-interacting properties of S. saccharolyticus and its role as a prevalent skin colonizer.

Non-Melanoma Skin Cancer: news from microbiota research

Recently, research has been deeply focusing on the role of the microbiota in numerous diseases, either affecting the skin or other organs. What it is well established is that its dysregulation promotes several cutaneous disorders (i.e. psoriasis and atopic dermatitis). To date, little is known about its composition, mediators and role in the genesis, progression and response to therapy of Non-Melanoma Skin Cancer (NMSC). Starting from a bibliographic study, we classified the selected articles into four sections: i) normal skin microbiota; ii) in vitro study models; iii) microbiota and NMSC and iv) probiotics, antibiotics and NMSC. What has emerged is how skin microflora changes, mainly represented by increases of Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa strains, modifications in the mutual quantity of β-Human papillomavirus genotypes, of Epstein Barr Virus and Malassezia or candidiasis, may contribute to the induction of a state of chronic self-maintaining inflammation, leading to cancer. In this context, the role of S. aureus and that of specific antimicrobial peptides look to be prominent. Moreover, although antibiotics may contribute to carcinogenesis, due to their ability to influence the microbiota balance, specific probiotics, such as Lacticaseibacillus rhamnosus GG, Lactobacillus johnsonii NCC 533 and Bifidobacteria spp., may be protective.

Lactobacillus reuteri DSM 17938 as a Novel Topical Cosmetic Ingredient: A Proof of Concept Clinical Study in Adults with Atopic Dermatitis

Atopic Dermatitis (AD) is a chronically relapsing skin condition characterized by dry, itchy, and inflamed skin where sufferers can frequently be subject to infections. Probiotics are known to be potent immune-modulators, and live Lactobacillus reuteri DSM 17938 has shown to be anti-inflammatory but also to possess antimicrobial and barrier function properties. This study aimed to investigate and compare two investigational ointment products (topical probiotic and control) for cutaneous acceptability, safety, and efficacy under normal conditions of use, in adult subjects with atopic dermatitis. The products were applied twice daily for 8 weeks, and cutaneous acceptability, SCORAD index, local SCORAD, and adverse events were evaluated after 4 and 8 weeks of treatment. At the end of the observations, it was demonstrated that both the probiotic-containing and probiotic-free ointments were both cutaneously acceptable and safe. It importantly showed a statistically and clinically significant improvement of the SCORAD index and local SCORAD in adult subjects with AD after 4 and 8 weeks of continuous use. In conclusion, we show evidence that the probiotic product, containing live L. reuteri DSM 17938 as an extra ingredient, is safe and promising as a novel topical cosmetic ointment and with further testing could be a standard topical product for the management of atopic dermatitis or other disorders associated with the skin.

Plant Complexity and Cosmetic Innovation

Plants have been used in cosmetic products since ancient times and are the subject of scientific investigation even nowadays. During the years, a deeper understanding of both the behavior of skin and of plants have become available drawing increasingly complex pictures. Plants are complex organisms that produce different metabolites responding to the environment they live in. Applied to the skin, phytomolecules interact with skin cells and affect the skin well-being and appearance. Ethnobotanical studies on the one hand and physico-chemical analyses on the other have pictured a rich inventory of plants with potential to enrich modern cosmetic products.

Extrinsic Factors Shaping the Skin Microbiome

Human skin, our most environmentally exposed organ, is colonized by a vast array of microorganisms constituting its microbiome. These bacterial communities are crucial for the fulfillment of human physiological functions such as immune system modulation and epidermal development and differentiation. The structure of the human skin microbiome is established during the early life stages, starting even before birth, and continues to be modulated throughout the entire life cycle, by multiple host-related and environmental factors. This review focuses on extrinsic factors, ranging from cosmetics to the environment and antibacterial agents, as forces that impact the human skin microbiome and well-being. Assessing the impact of these factors on the skin microbiome will help elucidate the forces that shape the microbial populations we coexist with. Furthermore, we will gain additional insight into their tendency to stimulate a healthy environment or to increase the propensity for skin disorder development.

Skin Physiology and its Microbiome as Factors Associated with the Recurrence of Pressure Injuries

BACKGROUND

Preventing recurrent pressure injuries (RPIs) is one of the important challenges faced in healthcare, but the risk factors of RPIs have not been fully revealed. This study aims to explore factors associated with RPIs, by focusing on skin physiology and its microbiome as local factors crucial for the health of healed tissue after pressure injury healing.

METHODS

This prospective observational study was conducted in a long-term care facility in Japan with patients whose PIs had healed within 1 month. Skin physiology was evaluated by stratum corneum (SC) hydration, pH, and transepidermal water loss. Skin bacteria was collected by tape stripping, followed by 16S ribosomal RNA-based metagenomics analysis. These parameters were evaluated every two weeks over a period of six weeks.

RESULTS

A total of 30 patients were included in this study, and 8 patients (26.7%) had an RPI within 6 weeks. In this study, significantly lower SC hydration and a higher rate of Staphylococcus species on the healed site were found in the RPI group.

DISCUSSION

A high rate of RPIs (about one in four) points out the necessity of a further care strategy on the healed PIs. Lower skin hydration and/or the increase in Staphylococcus bacteria may have a potential to be used as a biomarker for the prediction of RPIs, or may be an intervention point for the prevention of RPIs by, for example, skin cleansing with moisturizing care.

C-Type Lectin Receptors in Host Defense Against Bacterial Pathogens

Antigen-presenting cells (APCs) are present throughout the human body—in tissues, at barrier sites and in the circulation. They are critical for processing external signals to instruct both local and systemic responses toward immune tolerance or immune defense. APCs express an extensive repertoire of pattern-recognition receptors (PRRs) to detect and transduce these signals. C-type lectin receptors (CLRs) comprise a subfamily of PRRs dedicated to sensing glycans, including those expressed by commensal and pathogenic bacteria. This review summarizes recent findings on the recognition of and responses to bacteria by membrane-expressed CLRs on different APC subsets, which are discussed according to the primary site of infection. Many CLR-bacterial interactions promote bacterial clearance, whereas other interactions are exploited by bacteria to enhance their pathogenic potential. The discrimination between protective and virulence-enhancing interactions is essential to understand which interactions to target with new prophylactic or treatment strategies. CLRs are also densely concentrated at APC dendrites that sample the environment across intact barrier sites. This suggests an–as yet–underappreciated role for CLR-mediated recognition of microbiota-produced glycans in maintaining tolerance at barrier sites. In addition to providing a concise overview of identified CLR-bacteria interactions, we discuss the main challenges and potential solutions for the identification of new CLR-bacterial interactions, including those with commensal bacteria, and for in-depth structure-function studies on CLR-bacterial glycan interactions. Finally, we highlight the necessity for more relevant tissue-specific in vitro, in vivo and ex vivo models to develop therapeutic applications in this area.

Histoire naturelle de la dermatite atopique

Atopic dermatitis (AD) is a common frequent chronic inflammatory skin disease which begins frequently in infancy. The clinical expression of AD is a recurrent eczema on a dry skin. AD is a multifactorial disease characterized by two linked abnormalities: a skin barrier defect and a cellular inflammation, with type-2 main components. However, the pathophysiology of AD is not as simple as this description looks like. In this review, we will present a synthesis of current knowledge on natural history of AD and the involved factors, in order to clarify AD care. The evolution of AD is associated with many atopic comorbidities, following the "atopic march" scheme: IgE-mediated food allergy, allergic asthma and rhinitis occurring classically after AD. In fact, this is rarely the case, but the atopic march seems to be associated with AD severity. AD has also many neuropsychological complications which are essential to be detected. Other factors could influence the natural history of AD: genetic mutations on different genes (proteins of skin barrier, innate and adaptive immunity pathways), skin dysbiosis with colonization by Staphylococcus aureus, sensitization against environmental proteins. AD treatment is based on the restauration of the skin barrier using emollients and on anti-inflammatory drugs (notably topical corticosteroids) during the inflammatory flares. It is not recommended to treat the skin colonization by S. aureus, excepted in case of skin infection. The probiotics have no efficiency as curative treatment of AD, but could have an interest for the primary prevention, especially in at-risk populations. © 2019 Elsevier Masson SAS. All rights reserved.

Microbiome and skin biology

PURPOSE OF REVIEW

The skin is home to a diverse milieu of bacteria, fungi, viruses, bacteriophages, and archaeal communities. The application of culture-independent approaches has revolutionized the characterization of the skin microbiome and have revealed a previously underappreciated phylogenetic and functional granularity of skin-associated microbes in both health and disease states.

RECENT FINDINGS

The physiology of a given skin-niche drives the site-specific differences in bacterial phyla composition of healthy skin. Changes in the skin microbiome have consistently been associated with atopic dermatitis. In particular, Staphylococcus aureus overgrowth with concomitant decline in Staphylococcus epidermidis is a general feature associated with atopic dermatitis and is not restricted to eczematous lesions. Changes in fungal species are now also being described. Changes in the composition and metabolic activity of the gut microbiota are associated with skin health.

SUMMARY

We are now beginning to appreciate the intimate and intricate interactions between microbes and skin health. Multiple studies are currently focused on the manipulation of the skin or gut microbiome to explore their therapeutic potential in the prevention and treatment of skin inflammation.

Distinct Skin Microbiota Imbalance and Responses to Clinical Treatment in Children With Atopic Dermatitis

Background: Atopic dermatitis (AD) is a common cutaneous disease, associated with imbalances in the skin microbiota. Objective: To explore the characteristics of the cutaneous microbiota and its dynamic changes during clinical treatment. Methods: Cutaneous swab samples were collected from 51 AD patients before treatment, and 40 AD patients remained after a 2-week treatment with mometasone and mupirocin. Results: AD patients exhibited significant enrichments of Prevotella and Desulfovibrio as well as obvious reductions of Corynebacterium, Streptococcus and Parabacteroides. Based on the proportion of Staphylococcus aureus, the AD patients were further classified into S. aureus-predominant group (AD.S) and S. aureus-non-dominant (AD.ND) group. The AD.S group exhibited lower skin microbial diversity and higher atopic dermatitis (SCORAD) index. In the AD.S group, the cutaneous microbial diversity significantly increased from 2.9 ± 0.8 to 3.7 ± 1.0, while the relative abundance of S. aureus decreased from 42.5 ± 20.7 to 10.3 ± 28.4 after treatment. In contrast, no significant skin microbiota changes were detected in the AD.ND group. Conclusions: AD patients with predominant S. aureus had higher disease severity and lower microbiota diversity compared to patients in the AD.ND group. Mometasone and mupirocin therapy had significant effects on skin microbiota in AD.S patients, but had a paradoxical response in the AD.ND patients.

The Role of Cutibacterium acnes in Intervertebral Disc Inflammation

Recently, the role of infection of the intervertebral disc (IVD) with Cutibacterium acnes (C. acnes) as a contributor to disc-related low back pain (LBP) has been discussed. The aim of this study was to investigate whether and how C. acnes contributes to the inflammatory processes during IVD disease. The prevalence of C. acnes infection in human IVD tissue was determined by aerobic and anaerobic culture. Thereafter, primary human IVD cells were infected with a reference and a clinical C. acnes strain and analyzed for pro-inflammatory markers (gene/protein level). In a subsequent experiment, the involvement of the Toll-like receptor (TLR) pathway was investigated by co-treatment with sparstolonin B, a TLR2/4 inhibitor. We detected C. acnes in 10% of IVD biopsies (with either herniation or degeneration). Stimulating IVD cells with both C. acnes strains strongly and significantly upregulated expression of Interleukin (IL)-1β, IL-6, IL-8, and inducible nitric oxide synthase (iNOS). IL-6, cyclooxygenase (COX)-2, and iNOS expression was reduced upon TLR2/4 inhibition in 3 out of 5 donors, whereby responders and non-responders could not be differentiated by their basal TLR2 or TLR4 expression levels. We demonstrate that exposure of IVD cells to C. acnes induces an inflammatory response that may contribute to the development of discogenic LBP by involving TLR2/4 activation, yet only in a subgroup of patients. Whether the same response will be observed in vivo and where lower inoculums are present remains to be proven in future studies.

Exploration of the microbiome community for saliva, skin, and a mixture of both from a population living in Guangdong

The identification of biological traces provides vital evidence in forensic reconstruction at crime scenes, especially in sexual offences. Compared with traditional presumptive or confirmatory methods, the microbiome-based method has been proven to be of great value in body fluid identification. Mixture of body fluids or tissue is common in sexual assault cases; thus, it is essential to determine the sources of mixed samples. In this study, 60 samples consisting of skin, saliva, and a mixed model of saliva deposited on facial skin were collected from a population living in Guangdong. Through 16s rDNA high-throughput sequencing, we identified the predominant microbes in saliva samples, viz., Haemophilus parainfluenzae T3T1, Neisseria flava, Gemella haemolysans, Prevotella melaninogenica, and Actinomyces odontolyticus; in skin samples, Cutibacterium acnes and Corynebacterium tuberculostearicum were the predominant species. The microbial composition of the same body fluid or tissue is similar in different individuals. However, among different body fluids or tissue, the composition of microflora in saliva is more stable than that on skin. Additionally, the microbial community in the mixed model of saliva deposited on facial skin from the same and different individuals was clearly determined by the constituent fluids or tissue, apart from the differences among the donors. Overall, the microbiome-based method may have good potential as a tool for identifying single and mixed body fluid or tissue.

Targeting T2 Inflammation by Dupilumab Impacts on the Microbiomic "Ménage à Trois" of Atopic Dermatitis

Dupilumab leads to an improvement of the dysbiosis in lesional and non-lesional skin in atopic dermatitis (AD). Although the causal relationship between inflammation and dysbiosis remains unclear, strategies to normalize microbiome composition remain a relevant approach in AD. How and when to best individually impact on the microbiome to improve AD in the long-term and potentially modify disease is worthy of additional exploration.

Changes in latent fingermark glyceride composition as a function of sample age using UPLC-IMS-QToF-MSE

The composition of fingermark residue has been an important topic in forensic science, mainly in efforts to better understand and eventually improve the efficacy of latent fingermark detection methods. While the lipid fraction has been extensively studied, there is currently little information about how the glyceride fraction of latent fingermarks is chemically altered over time following deposition. A previously reported untargeted ultra performance liquid chromatography-ion mobility spectrometry-quadrupole time-of-flight mass spectrometry (UPLC-IMS-QToF-MS^E) method was used to investigate changes over time in fingermark di- and triglycerides. Charged latent fingermark samples from 5 donors were analysed up to 28 days following deposition. Significant changes in glyceride composition occurred with increased sample age, attributed primarily to the oxidation of unsaturated triglycerides through ozonolysis. Considerably fewer unsaturated TGs were identified in samples 7 and 28 days following deposition, while mono- and diozonides of these lipids were identified as major components of aged samples. Additional compounds were identified as possible aldehyde and carboxylic acid derivatives resulting from the reaction of water with ozonolysis intermediates. While the onset of these processes occurred rapidly following deposition, continuing oxidation over time was seen via the progressive ozonolysis of diunsaturated triglycerides. These results represent a further step towards understanding the factors affecting fingermark composition, ageing and subsequent detection under operational conditions.

Potential of Skin Microbiome, Pro- and/or Pre-Biotics to Affect Local Cutaneous Responses to UV Exposure

The human skin hosts innumerable microorganisms and maintains homeostasis with the local immune system despite the challenges offered by environmental factors such as ultraviolet radiation (UVR). UVR causes cutaneous alterations such as acute (i.e., sunburn) and chronic inflammation, tanning, photoaging, skin cancer, and immune modulation. Phototherapy on the other hand is widely used to treat inflammatory skin diseases such as psoriasis, atopic dermatitis, polymorphic light eruption and graft-versus-host disease (GvHD), as well as neoplastic skin diseases such as cutaneous T cell lymphoma, among others. Previous work has addressed the use of pro- and pre-biotics to protect against UVR through anti-oxidative, anti-inflammatory, anti-aging, anti-carcinogenic and/or pro-and contra-melanogenic properties. Herein, we discuss and share perspectives of the potential benefits of novel treatment strategies using microbes and pro- and pre-biotics as modulators of the skin response to UVR, and how they could act both for protection against UVR-induced skin damage and as enhancers of the UVR-driven therapeutic effects on the skin.

Antimicrobial activities of bacterial cellulose - Silver montmorillonite nanocomposites for wound healing

A nanocomposite based on bacterial cellulose (BC) containing montmorillonite (MMT) modified with silver (BC-MMT-Ag) was developed to be used as potential scaffold for wound healing. Montmorillonite was suspended in silver nitrate solution to incorporate silver in the matrix by ion exchange. The derivative silver clay suspension was used to modify bacterial cellulose membranes by ex situ technique. The BC nanocomposite was analyzed by thermal analysis, scanning electron microscopy, Fourier transform infrared and electron dispersion spectroscopies, X-ray diffraction, and rehydration capacity. The antimicrobial activity of the silver montmorillonite-bacterial cellulose nanocomposite was challenged in cultures of Gram(+) Staphylococcus aureus and Gram(-) Pseudomonas aeruginosa, and showed inhibition of growth in agar plates and biofilm formation as revealed by live-dead assay. Cytotoxicity of BC nanocomposites containing 1% to 25% of MMT-Ag showed good in vitro biocompatibility with L929 fibroblast cells.

Temporal variations in bacterial community diversity and composition throughout intensive care unit renovations

BACKGROUND

Inanimate surfaces within a hospital serve as a reservoir of microbial life that may colonize patients and ultimately result in healthcare associated infections (HAIs). Critically ill patients in intensive care units (ICUs) are particularly vulnerable to HAIs. Little is known about how the microbiome of the ICU is established or what factors influence its evolution over time. A unique opportunity to bridge the knowledge gap into how the ICU microbiome evolves emerged in our health system, where we were able to characterize microbial communities in an established hospital ICU prior to closing for renovations, during renovations, and then after re-opening.

RESULTS

We collected swab specimens from ICU bedrails, computer keyboards, and sinks longitudinally at each renovation stage, and analyzed the bacterial compositions on these surfaces by 16S rRNA gene sequencing. Specimens collected before ICU closure had the greatest alpha diversity, while specimens collected after the ICU had been closed for over 300 days had the least. We sampled the ICU during the 45 days after re-opening; however, within that time frame, the alpha diversity never reached pre-closure levels. There were clear and significant differences in microbiota compositions at each renovation stage, which was driven by environmental bacteria after closure and human-associated bacteria after re-opening and before closure.

CONCLUSIONS

Overall, we identified significant differences in microbiota diversity and community composition at each renovation stage. These data help to decipher the evolution of the microbiome in the most critical part of the hospital and demonstrate the significant impacts that microbiota from patients and staff have on the evolution of ICU surfaces. Video Abstract.

Nano-Vesicle Based Anti-Fungal Formulation Shows Higher Stability, Skin Diffusion, Biosafety and Anti-Fungal Efficacy In Vitro

Opportunistic fungal infections are responsible for over 1.5 million deaths per year. This has created a need for highly effective antifungal medication to be as potent as possible. In this study, we improved the efficacy of a common over the counter (OTC) antifungal skin medication, miconazole, by encapsulating nano-molecules of the drug in cholesterol/sodium oleate nano-vesicles. These nano-vesicles were characterized to optimize their size, zeta potential, polydispersity index and encapsulation efficiency. Furthermore, these nano-vesicles were compared to a conventional miconazole-based commercially available cream to determine potential improvements via permeation through the stratum corneum, cytotoxicity, and antifungal capabilities. Our results found that the vesicle size was within the nano range (~300 nm), with moderate polydispersity and stability. When compared with the commercially available cream, Actavis, as well as free miconazole, the miconazole nano-vesicle formulation displayed enhanced fungal inhibition by a factor of three or more when compared to free miconazole. Furthermore, with smaller nanoparticle (NP) sizes, higher percentages of miconazole may be delivered, further enhancing the efficacy of miconazole's antifungal capability. Cytotoxicity studies conducted with human dermal fibroblast cells confirm its biosafety and biocompatibility, as cell survival rate was observed to be twofold higher in nano-vesicle formulation than free miconazole. This formulation has the potential to treat fungal infections through increasing the retention time in the skin, improving the treatment approach, and by enhancing the efficacy via the use of nano-vesicles.

High Levels of Oxidative Stress Create a Microenvironment That Significantly Decreases the Diversity of the Microbiota in Diabetic Chronic Wounds and Promotes Biofilm Formation

Diabetics chronic wounds are characterized by high levels of oxidative stress (OS) and are often colonized by biofilm-forming bacteria that severely compromise healing and can result in amputation. However, little is known about the role of skin microbiota in wound healing and chronic wound development. We hypothesized that high OS levels lead to chronic wound development by promoting the colonization of biofilm-forming bacteria over commensal/beneficial bacteria. To test this hypothesis, we used our db/db^−/− mouse model for chronic wounds where pathogenic biofilms develop naturally after induction of high OS immediately after wounding. We sequenced the bacterial rRNA internal transcribed spacer (ITS) gene of the wound microbiota from wound initiation to fully developed chronic wounds. Indicator species analysis, which considers a species' fidelity and specificity, was used to determine which bacterial species were strongly associated with healing wounds or chronic wounds. We found that healing wounds were colonized by a diverse and dynamic bacterial microbiome that never developed biofilms even though biofilm-forming bacteria were present. Several clinically relevant species that are present in human chronic wounds, such as Cutibacterium acnes, Achromobacter sp., Delftia sp., and Escherichia coli, were highly associated with healing wounds. These bacteria may serve as bioindicators of healing and may actively participate in the processes of wound healing and preventing pathogenic bacteria from colonizing the wound. In contrast, chronic wounds, which had high levels of OS, had low bacterial diversity and were colonized by several clinically relevant, biofilm-forming bacteria such as Pseudomonas aeruginosa, Enterobacter cloacae, Corynebacterium frankenforstense, and Acinetobacter sp. We observed unique population trends: for example, P. aeruginosa associated with aggressive biofilm development, whereas Staphylococcus xylosus was only present early after injury. These findings show that high levels of OS in the wound significantly altered the bacterial wound microbiome, decreasing diversity and promoting the colonization of bacteria from the skin microbiota to form biofilm. In conclusion, bacteria associated with non-chronic or chronic wounds could function as bioindicators of healing or non-healing (chronicity), respectively. Moreover, a better understanding of bacterial interactions between pathogenic and beneficial bacteria within an evolving chronic wound microbiota may lead to better solutions for chronic wound management.

The Microbiome and the Gut-Liver-Brain Axis for Central Nervous System Clinical Pharmacology: Challenges in Specifying and Integrating In Vitro and In Silico Models

The complexity of integrating microbiota into clinical pharmacology, environmental toxicology, and opioid studies arises from bidirectional and multiscale interactions between humans and their many microbiota, notably those of the gut. Hosts and each microbiota are governed by distinct central dogmas, with genetics influencing transcriptomics, proteomics, and metabolomics. Each microbiota's metabolome differentially modulates its own and the host's multi‐omics. Exogenous compounds (e.g., drugs and toxins), often affect host multi‐omics differently than microbiota multi‐omics, shifting the balance between drug efficacy and toxicity. The complexity of the host‐microbiota connection has been informed by current methods of in vitro bacterial cultures and in vivo mouse models, but they fail to elucidate mechanistic details. Together, in vitro organ‐on‐chip microphysiological models, multi‐omics, and in silico computational models have the potential to supplement the established methods to help clinical pharmacologists and environmental toxicologists unravel the myriad of connections between the gut microbiota and host health and disease.

Overview of the Potential Role of Malassezia in Gut Health and Disease

Malassezia is the most prevalent fungus identified in the human skin microbiota; originally described at the end of the nineteenth century, this genus is composed of at least 14 species. The role of Malassezia on the skin remains controversial because this genus has been associated with both healthy skin and pathologies (dermatitis, eczema, etc.). However, with the recent development of next-generation sequencing methods, allowing the description of the fungal diversity of various microbiota, Malassezia has also been identified as a resident fungus of diverse niches such as the gut or breast milk. A potential role for Malassezia in gut inflammation and cancer has also been suggested by recent studies. The aim of this review is to describe the findings on Malassezia in these unusual niches, to investigate what is known of the adaptation of Malassezia to the gut environment and to speculate on the role of this yeast in the host physiology specifically related to the gastrointestinal tract.

Eye-Catching Microbes-Polyphasic Analysis of the Microbiota on Microscope Oculars Verifies Their Role as Fomites

Microscopes are used in virtually every biological and medical laboratory. Previous cultivation-based studies have suggested that direct contact with microscope eyepieces increases the risk of eye infections. To obtain a deeper insight into the microbiota on oculars, we analysed 10 recently used university microscopes. Their left oculars were used for a cultivation-based approach, while the right oculars served for massive gene sequencing. After cleaning with isopropyl alcohol, the oculars were re-sampled and analysed again. All oculars were found to be contaminated with bacteria, with a maximum load of 1.7 × 10³ CFU cm^-2. MALDI Biotyping revealed mainly Cutibacterium (68%), Staphylococcus (14%) and Brevibacterium (10%), with the most abundant species being Cutibacterium acnes (13%) and Staphylococcus capitis (6%). Cleaning reduced the microbial load by up to 2 log scales. Within 10 uncleaned and 5 cleaned samples, 1480 ASVs were assigned to 10 phyla and 262 genera. The dominant genera before cleaning were Cutibacterium (78%), Paracoccus (13%), Pseudomonas (2%) and Acinetobacter (1%). The bacteriota composition on the cleaned oculars was similar; however, it probably largely represented dead bacteria. In summary, used oculars were significantly contaminated with skin and environmental bacteria, including potential pathogens. Regular cleaning is highly recommended to prevent eye and skin infections.

Novel Peptide from Commensal Staphylococcus simulans Blocks Methicillin-Resistant Staphylococcus aureus Quorum Sensing and Protects Host Skin from Damage

Recent studies highlight the abundance of commensal coagulase-negative staphylococci (CoNS) on healthy skin. Evidence suggests that CoNS actively shape the skin immunological and microbial milieu to resist colonization or infection by opportunistic pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), in a variety of mechanisms collectively termed colonization resistance. One potential colonization resistance mechanism is the application of quorum sensing, also called the accessory gene regulator (agr) system, which is ubiquitous among staphylococci. Common and rare CoNS make autoinducing peptides (AIPs) that function as MRSA agr inhibitors, protecting the host from invasive infection. In a screen of CoNS spent media, we found that Staphylococcus simulans, a rare human skin colonizer and frequent livestock colonizer, released potent inhibitors of all classes of MRSA agr signaling. We identified three S. simulans agr classes and have shown intraspecies cross talk between noncognate S. simulans agr types for the first time. The S. simulans AIP-I structure was confirmed, and the novel AIP-II and AIP-III structures were solved via mass spectrometry. Synthetic S. simulans AIPs inhibited MRSA agr signaling with nanomolar potency. S. simulans in competition with MRSA reduced dermonecrotic and epicutaneous skin injury in murine models. The addition of synthetic AIP-I also effectively reduced MRSA dermonecrosis and epicutaneous skin injury in murine models. These results demonstrate potent anti-MRSA quorum sensing inhibition by a rare human skin commensal and suggest that cross talk between CoNS and MRSA may be important in maintaining healthy skin homeostasis and preventing MRSA skin damage during colonization or acute infection.

Continental-Scale Microbiome Study Reveals Different Environmental Characteristics Determining Microbial Richness, Composition, and Quantity in Hotel Rooms

This is the first microbiome study to characterize the microbiome data and associated environmental characteristics in hotel environments. In this study, we found concordant variation between fungal compositional variation and absolute quantity and discordant variation between community variation/quantity and richness. Our study can be used to promote hotel hygiene standards and provide resource information for future microbiome and exposure studies associated with health effects in hotel rooms.

Culture-independent microbiome surveys have been conducted in homes, hospitals, schools, kindergartens and vehicles for public transport, revealing diverse microbial distributions in built environments. However, microbiome composition and the associated environmental characteristics have not been characterized in hotel environments. We presented here the first continental-scale microbiome study of hotel rooms (n = 68) spanning Asia and Europe. Bacterial and fungal communities were described by amplicon sequencing of the 16S rRNA gene and internal transcribed spacer (ITS) region and quantitative PCR. Similar numbers of bacterial (4,344) and fungal (4,555) operational taxonomic units were identified in the same sequencing depth, but most fungal taxa showed a restricted distribution compared to bacterial taxa. Aerobic, ubiquitous bacteria dominated the hotel microbiome with compositional similarity to previous samples from building and human nasopharynx environments. The abundance of Aspergillus was negatively correlated with latitude and accounted for ∼80% of the total fungal load in seven low-latitude hotels. We calculated the association between hotel microbiome and 16 indoor and outdoor environmental characteristics. Fungal composition and absolute quantity showed concordant associations with the same environmental characteristics, including latitude, quality of the interior, proximity to the sea, and visible mold, while fungal richness was negatively associated with heavy traffic (95% confidence interval [CI] = −127.05 to −0.25) and wall-to-wall carpet (95% CI = −47.60 to −3.82). Bacterial compositional variation was associated with latitude, quality of the interior, and floor type, while bacterial richness was negatively associated with recent redecoration (95% CI −179.00 to −44.55) and mechanical ventilation (95% CI = −136.71 to −5.12).

IMPORTANCE This is the first microbiome study to characterize the microbiome data and associated environmental characteristics in hotel environments. In this study, we found concordant variation between fungal compositional variation and absolute quantity and discordant variation between community variation/quantity and richness. Our study can be used to promote hotel hygiene standards and provide resource information for future microbiome and exposure studies associated with health effects in hotel rooms.

Draft Genome Sequence of Staphylococcus epidermidis UMB7765, Isolated from the Urobiome of a Woman with Recurrent Urinary Tract Infection

Staphylococcus epidermidis is a Gram-positive bacterium that is resistant to many antibiotics. Here, we present the 2.5-Mb draft genome of S. epidermidis UMB7765, isolated from a voided urine sample from a female with recurrent urinary tract infections.