Biofilm of Cutibacterium acnes: a target of different active substances

BACKGROUND

Acne vulgaris is a chronic inflammatory dermatosis. Cutibacterium acnes plays a crucial role in the acne pathophysiology. Recent works present evidence of C. acnes growing as a biofilm in cutaneous follicles. This development is currently considered one of the leading causes of C. acnes in vivo persistence and resistance to antimicrobials used to treat acne.

OBJECTIVE

Our objective was to evaluate the effects of various active compounds (clindamycin, erythromycin, doxycycline, and myrtle extract) on eight distinct, well-characterized strains of C. acnes following their growth in biofilm mode.

METHODS/RESULTS

Cutibacterium acnes isolates from phylotypes IA1 and IA2 produce more biofilm than other phylotypes. No antibiotic effect was observed either during the curative test or preventive test. Myrtle extract at 0.01% (w/v) showed significant efficacy on the biofilm for C. acnes strains (curative assays). Furthermore, it appear that myrtle extract and doxycycline together reduce the overall biomass of the biofilm. A significant dose-dependent effect was observed during the preventive test, greater than the one observed under curative conditions, with an important loss of activity of the myrtle extract observed from 0.001% (w/v) concentration onwards. Transmission electron microscopy showed that bacteria treated with myrtle extract grew biofilms much less frequently than untreated bacteria. Additionally, when the quantity of myrtle extract grew, the overall number of bacteria dropped, indicating an additional antibacterial action.

CONCLUSION

These findings support the hypothesis that the different C. acnes phylotypes have various aptitudes in forming biofilms. They also suggest that myrtle extract is a promising alternative as an anti-biofilm and antibacterial agent in fighting diseases caused by planktonic and biofilm C. acnes.

Effect of Potassium Permanganate on Staphylococcal Isolates Derived from the Skin of Patients with Atopic Dermatitis

In atopic dermatitis (AD), Staphylococcus aureus frequently colonizes lesions, leading to superinfections that can then lead to exacerbations. The presence of biofilm-producing isolates has been associated with worsening of the disease. Potassium permanganate is used as a topical treatment of infected eczema, blistering conditions, and wounds. Little is known of its effects against microbes in AD skin. The aim of this study was to explore antibacterial and antibiofilm properties of potassium permanganate against staphylococcal isolates derived from AD skin. Viable count and radial diffusion assays were used to investigate antibacterial effects of potassium permanganate against planktonic staphylococcal isolates. The antibiofilm effects were assessed using biofilm assays and scanning electron microscopy. The Staphylococcus aureus isolates were completely killed when exposed to 0.05% of potassium permanganate. In concentrations of 0.01%, potassium permanganate inhibited bacterial biofilm formation. Eradication of established staphylococcal biofilm was observed in concentrations of 1%. Electron microscopy revealed dense formations of coccoidal structures in growth control and looser formations of deformed bacteria when exposed to potassium permanganate. This suggests antibacterial and antibiofilm effects of potassium permanganate against staphylococcal isolates derived from AD skin, when tested in vitro, and a potential role in the treatment of superinfected AD skin.

Interaction between Sophorolipids and β-glucan in Aqueous Solutions

Skin disorders, including acne vulgaris, atopic dermatitis, and rosacea, are characterized by the presence of biofilms, which are communities of microorganisms. The mechanical stability of biofilms is attributed to one of their constituents-polysaccharides-which are secreted by microorganisms. Sophorolipids are biosurfactants with biofilm disruption and removal abilities and are expected to become alternatives for classical petrochemical-based surfactants in cosmetics. In this study, we investigated the influence of sophorolipids on β-glucan such as dispersion status, interaction mechanism, and configuration change as a model polysaccharide of biofilm in aqueous solution. Dynamic light scattering measurements showed that sophorolipids interfere with the aggregation of β- glucan in aqueous solutions. In contrast, sodium dodecyl sulfate (SDS), which is used as a typical surfactant reference, promotes the aggregation of β-glucan. The interaction between sophorolipids and β-glucan were investigated using surface tension measurements and isothermal titration calorimetry (ITC). Surface tension increased only near critical micelle concentration (CMC) region of sophorolipids in the presence of β-glucan. This suggests that the interaction occurred in the solution rather than at the air-liquid interface. Moreover, the results of ITC indicate that hydrophobic interactions were involved in this interaction. In addition, the results of optical rotation measurements indicate that sophorolipids did not unfold the triple helical structure of β-glucan. β-glucan dispersion was expected to be caused steric hindrance and electrostatic repulsion when sophorolipids interacted with β-glucan via hydrophobic interactions owing to the unique molecular structure of sophorolipids attributed by a bulky sugar moiety and a carboxyl functional group. These results demonstrated unique performances of sophorolipids on β-glucan and provided more insights on the efficacy of sophorolipids as good anti-biofilms.

Bactericidal effect of Iberin combined with photodynamic antimicrobial chemotherapy against Pseudomonas aeruginosa biofilm cultured on ex vivo wound model

Wounds infected by Pseudomonas aeruginosa (P. aeruginosa) biofilms are characterized by poor healing and by being long lasting. Pyocyanin and pyoverdine are exotoxins that contribute to P. aeruginosa pathogenicity in wound infections and are known as virulence factors. Despite the usefulness of antimicrobial photodynamic therapy (PDT) in the management of wound infections, biofilms are hurdle for microbial photoinactivation. Quorum sensing (QS) is a cell density-dependent chemical signaling system P. aeruginosa uses to regulate biofilm formation and virulence factors production. In the current study, QS attenuation was used in combination with PDT against P. aeruginosa biofilm cultured on skin explant. Iberin is a QS inhibitor that attenuates P. aeruginosa virulence and affects biofilm integrity. The antibiofilm and QS inhibitory activities of iberin in combination with either riboflavin or 5,10,15,20-Tetrakis(1-methyl-4-pyridinio) porphyrin tetra p-toluenesulfonate (TMP) mediated PDT were investigated using viable count method and pyocyanin and pyoverdine assays, respectively. No bactericidal activity was reported when iberin was added to a mature biofilm (24 h) followed by PDT. When added to a growing biofilm at multiple time points (0 h, 24 h and 48 h), iberin inhibited P. aeruginosa biofilm QS signaling system. This inhibitory effect resulted in an observable decrease in the levels of the QS-regulated virulence factors, pyocyanin and pyoverdine, without any effect on the growth of the biofilm cultures. These changes in biofilm virulence were associated with a decrease in biofilm resistance to PDT and caused bactericidal effect upon photosensitizers treatment and irradiation. Iberin-treated-riboflavin-mediated PDT resulted in a significant 1.3 log reduction in biofilm population. Similarly, iberin-treated-TMP-mediated PDT caused a significant 1.8 log reduction in biofilm population. The combination of QS inhibitor with PDT is a promising alternative antimicrobial therapy for the management of biofilms.

Flexible polymeric patch based nanotherapeutics against non-cancer therapy

Flexible polymeric patches find widespread applications in biomedicine because of their biological and tunable features including excellent patient compliance, superior biocompatibility and biodegradation, as well as high loading capability and permeability of drug. Such polymeric patches are classified into microneedles (MNs), hydrogel, microcapsule, microsphere and fiber depending on the formed morphology. The combination of nanomaterials with polymeric patches allows for improved advantages of increased curative efficacy and lowered systemic toxicity, promoting on-demand and regulated drug administration, thus providing the great potential to their clinic translation. In this review, the category of flexible polymeric patches that are utilized to integrate with nanomaterials is briefly presented and their advantages in bioapplications are further discussed. The applications of nanomaterials embedded polymeric patches in non-cancerous diseases were also systematically reviewed, including diabetes therapy, wound healing, dermatological disease therapy, bone regeneration, cardiac repair, hair repair, obesity therapy and some immune disease therapy. Alternatively, the limitations, latest challenges and future perspectives of such biomedical therapeutic devices are addressed.

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The most explored polymeric patches, such as microneedle, hydrogel, microsphere, microcapsule, and fiber are summarized.

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Polymeric patches integrated with a diversity of nanomaterials are systematically overviewed in non-cancer therapy.

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The future prospective for the development of polymeric patch based nanotherapeutics is discussed.

Noninflammatory comedones have greater diversity in microbiome and are more prone to biofilm formation than inflammatory lesions of acne vulgaris

BACKGROUND

The ability of Cutibacterium acnes strains to form biofilms has been correlated with their virulence.

OBJECTIVE

This study examined biofilm and skin microbiota in acne patients in order to understand their role in the development of acne lesions.

METHODS

Thin sections of punch biopsy specimens of (i) uninflamed comedones, (ii) inflammatory lesions, and (iii) uninvolved adjacent skin of acne patients were examined. Epiflourescence and confocal laser scanning microscopy were used for biofilm detection, and pyrosequencing with taxonomic classification of 16s rRNA gene amplicons was used for microbiota analysis.

RESULTS

Of the 39 skin specimens from patients with mild-moderate acne (n = 13) that were studied, nine (23%) contained biofilm. Among these specimens, biofilm was most frequently detected in comedones (55.6%) and less frequently in inflammatory papules (22.2%) and uninvolved skin (22.2%). Comedones demonstrated the highest mean alpha diversity of all the lesion subtypes. The relative abundance of Staphylococcus was significantly higher in comedones (11.400% ± 12.242%) compared to uninvolved skin (0.073% ± 0.185%, P = 0.024).

CONCLUSIONS

The microenvironment of the comedone differs from that of inflammatory lesions and unaffected skin. The increased frequency of biofilm in comedones may account for the lack of host inflammatory response to these lesions.

Virulence factors and clonal diversity of Staphylococcus aureus in colonization and wound infection with emphasis on diabetic foot infection

Foot ulcer is a common complication in diabetic subjects and infection of these wounds contributes to increased rates of morbidity and mortality. Diabetic foot infections are caused by a multitude of microbes and Staphylococcus aureus, a major nosocomial and community-associated pathogen, significantly contributes to wound infections as well. Staphylococcus aureus is also the primary pathogen commonly associated with diabetic foot osteomyelitis and can cause chronic and recurrent bone infections. The virulence capability of the pathogen and host immune factors can determine the occurrence and progression of S. aureus infection. Pathogen-related factors include complexity of bacterial structure and functional characteristics that provide metabolic and adhesive properties to overcome host immune response. Even though, virulence markers and toxins of S. aureus are broadly similar in different wound models, certain distinguishing features can be observed in diabetic foot infection. Specific clonal lineages and virulence factors such as TSST-1, leukocidins, enterotoxins, and exfoliatins play a significant role in determining wound outcomes. In this review, we describe the role of specific virulence determinants and clonal lineages of S. aureus that influence wound colonization and infection with special reference to diabetic foot infections.

Development of Pseudomonas aeruginosa Biofilms in Partial-Thickness Burn Wounds Using a Sprague-Dawley Rat Model

We used a modified Walker–Mason scald burn rat model to demonstrate that Pseudomonas aeruginosa, a common opportunistic pathogen in the burn ward and notable biofilm former, establishes biofilms within deep partial-thickness burn wounds in rats.

Deep partial-thickness burn wounds, ~10% of the TBSA, were created in anesthetized male Sprague-Dawley rats (350–450 g; n = 84). Immediately post-burn, 100 µl of P. aeruginosa in phosphate-buffered saline at 1 × 10³, 1 × 10⁴, or 1 × 10⁵ cells/wound was spread over the burn surface . At 1, 3, 7, and 11 days post-burn, animals were euthanized and blood and tissue were collected for complete blood counts, colony-forming unit (CFU) counts, biofilm gene expression, histology, scanning electron microscopy (SEM), and myeloperoxidase activity in the burn eschar.

P. aeruginosa developed robust biofilm wound infections, plateauing at ~1 × 10⁹ CFU/g burn tissue within 7 days regardless of inoculum size. Expression of Pseudomonas alginate genes and other virulence factors in the infected wound indicated formation of mature P. aeruginosa biofilm within the burn eschar. Compared to un-inoculated wounds, P. aeruginosa infection caused both local and systemic immune responses demonstrated by changes in systemic neutrophil counts, histology, and myeloperoxidase activity within the burn wound. Additionally, SEM showed P. aeruginosa enmeshed within an extracellular matrix on the burn surface as well as penetrating 500–600 µm deep into the eschar.

P. aeruginosa establishes biofilms within deep partial-thickness burn wounds and invades deep into the burned tissue. This new in vivo biofilm infection model is valuable for testing novel anti-biofilm agents to advance burn care.

Malassezia colonisation on a reconstructed human epidermis: Imaging studies

BACKGROUND

Biofilm formation represents a major microbial virulence attribute especially at epithelial surfaces such as the skin. Malassezia biofilm formation at the skin surface has not yet been addressed.

OBJECTIVE

The present study aimed to evaluate Malassezia colonisation pattern on a reconstructed human epidermis (RhE) by imaging techniques.

METHODS

Malassezia clinical isolates were previously isolated from volunteers with pityriasis versicolor and seborrhoeic dermatitis. Yeast of two strains of M furfur and M sympodialis were inoculated onto the SkinEthic^™ RHE. The tissues were processed for light microscopy, wide-field fluorescence microscopy and scanning electron microscopy.

RESULTS

Colonisation of the RhE surface with aggregates of Malassezia yeast entrapped in a multilayer sheet with variable amount of extracellular matrix was unveiled by imaging techniques following 24, 48, 72 and 96 hours of incubation. Whenever yeast were suspended in RPMI medium supplemented with lipids, the biofilm substantially increased with a dense extracellular matrix in which the yeast cells were embedded. Slight differences were found in the biofilm architectural structure between the two tested species with an apparently higher entrapment and viscosity in M furfur biofilm.

CONCLUSION

Skin isolates of M furfur and M sympodialis were capable of forming biofilm in vitro at the epidermal surface simulating in vivo conditions. Following 24 hours of incubation, without added lipids, rudimental matrix was barely visible, conversely to the reported at plastic surfaces. The amount of biofilm apparently increased progressively from 48 to 96 hours. A structural heterogeneity of biofilm between species was found.

From pathogenesis of acne vulgaris to anti-acne agents

Acne vulgaris is a cutaneous chronic inflammatory disorder with complex pathogenesis. Four factors play vital roles in acne pathophysiology: hyperseborrhea and dysseborrhea, altered keratinization of the pilosebaceous duct, Cutibacterium acnes (C. acnes) and inflammation. The main hormones responsible for the development of acne vulgaris include androgens, insulin and insulin-like growth factor-1. Other factors involved in this process are corticotropin-releasing hormone, α-melanocyte-stimulating hormone and substance P. Wnt/β-catenin signaling pathway, phosphoinositide 3-kinase (PI3K)/Akt pathway, mitogen-activated protein kinase pathway, adenosine 5'-monophosphate-activated protein kinase pathway and nuclear factor kappa B pathway participate in the modulation of sebocyte, keratinocyte and inflammatory cell (e.g. lymphocytes, monocytes, macrophages, neutrophils) activity. Among all the triggers and pathways mentioned above, IGF-1-induced PI3K/Akt/Forkhead box protein O1/mammalian target of rapamycin (mTOR) C1 pathway is the most important signaling responsible for acne pathogenesis. Commonly used anti-acne agents include retinoids, benzoyl peroxide, antibiotics and hormonal agents (e.g. spironolactone, combination oral contraceptive and flutamide). New approaches including peroxisome proliferator-activated receptor γ modifier, melanocortin receptor antagonists, epigallocatechin-3-gallate, metformin, olumacostat glasaretil, stearoyl-CoA desaturase inhibitor omiganan pentahydrochloride, K_DPT, afamelanotide, apremilast and biologics have been developed as promising treatments for acne vulgaris. Although these anti-acne agents have various pharmacological effects against the diverse pathogenesis of acne, all of them have a synergistic mode of action, the attenuation of Akt/mTORC1 signaling and enhancement of p53 signal transduction. In addition to drug therapy, diet with no hyperglycemic carbohydrates, no milk and dairy products is also beneficial for treatment of acne.

Staphylococcal Biofilms in Atopic Dermatitis

PURPOSE OF REVIEW

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disorder that is a major public health burden worldwide. AD lesions are often colonized by Staphylococcus aureus and Staphylococcus epidermidis. An important aspect of Staphylococcus spp. is their propensity to form biofilms, adhesive surface-attached colonies that become highly resistant to antibiotics and immune responses, and recent studies have found that clinical isolates colonizing AD skin are often biofilm-positive. Biofilm formation results in complex bacterial communities that have unique effects on keratinocytes and host immunity. This review will summarize recent studies exploring the role of staphyloccocal biofilms in atopic dermatitis and the implications for treatment.

RECENT FINDINGS

Recent studies suggest an important role for biofilms in the pathogenesis of numerous dermatologic diseases including AD. S. aureus biofilms have been found to colonize the eccrine ducts of AD skin, and these biofilms influence secretion of keratinocyte cytokines and trigger differentiation and apoptosis of keratinocytes. These activities may act to disrupt barrier function and promote disease pathogenesis as well as allergen sensitization. Formation of biofilm is a successful strategy that protects the bacteria from environmental danger, antibiotics, and phagocytosis, enabling chronic persistence in the host. An increasing number of S. aureus skin isolates are resistant to conventional antibiotics, and staphylococcal biofilm communities are prevalent on the skin of individuals with AD. Staphylococcal colonization of the skin impacts skin barrier function and plays multiple important roles in AD pathogenesis.

Identification of bacterial biofilm and the Staphylococcus aureus derived protease, staphopain, on the skin surface of patients with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by an impaired epidermal barrier, dysregulation of innate and adaptive immunity, and a high susceptibility to bacterial colonization and infection. In the present study, bacterial biofilm was visualized by electron microscopy at the surface of AD skin. Correspondingly, Staphylococcus aureus (S. aureus) isolates from lesional skin of patients with AD, produced a substantial amount of biofilm in vitro. S. aureus biofilms showed less susceptibility to killing by the antimicrobial peptide LL-37 when compared with results obtained using planktonic cells. Confocal microscopy analysis showed that LL-37 binds to the S. aureus biofilms. Immuno-gold staining of S. aureus biofilm of AD skin detected the S. aureus derived protease staphopain adjacent to the bacteria. In vitro, staphopain B degraded LL-37 into shorter peptide fragments. Further, LL-37 significantly inhibited S. aureus biofilm formation, but no such effects were observed for the degradation products. The data presented here provide novel information on staphopains present in S. aureus biofilms in vivo, and illustrate the complex interplay between biofilm and LL-37 in skin of AD patients, possibly leading to a disturbed host defense, which facilitates bacterial persistence.

Antibacterial and antibiofilm effects of sodium hypochlorite against Staphylococcus aureus isolates derived from patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by an increased susceptibility to skin infections. Staphylococcus aureus is reported to dominate in AD lesions and reports have revealed the presence of staphylococcal biofilms. These infections contribute to aggravation of the eczema. Sodium hypochlorite is known to reduce bacterial load of skin lesions, as well as disease severity, in patients with AD, but the effect on biofilms is unknown.

OBJECTIVES

To investigate the antimicrobial and antibiofilm effects of sodium hypochlorite against S. aureus isolates derived from patients with AD.

METHODS

Skin biopsies derived from patients with infected AD were examined by scanning electron microscopy (SEM). Using radial diffusion assays, biofilm assays and confocal laser scanning microscopy, we assessed the effect of sodium hypochlorite on S. aureus isolates derived from lesional skin of patients with AD.

RESULTS

SEM revealed clusters of coccoid bacteria embedded in fibrin and extracellular substances at the skin of a patient with infected AD. At concentrations of 0·01-0·08%, sodium hypochlorite showed antibacterial effects against planktonic cells. Eradication of S. aureus biofilms in vitro was observed in concentrations ranging from 0·01% to 0·16%. Confocal laser scanning microscopy confirmed these results. Finally, when human AD skin was subjected to sodium hypochlorite in an ex vivo model, a dose of 0·04% reduced the bacteria derived from AD skin.

CONCLUSIONS

Sodium hypochlorite has antimicrobial and antibiofilm effects against clinical S. aureus isolates. Our findings suggest usage of a higher concentration than currently used in bleach baths of patients with skin-infected AD.

Anti-Acne Activity of Italian Medicinal Plants Used for Skin Infection

Propionibacterium acnes is implicated in the pathogenesis of acne vulgaris, which impacts >85% of teenagers. Novel therapies are in high demand and an ethnopharmacological approach to discovering new plant sources of anti-acne therapeutics could contribute to filling this void in effective therapies. The aims of our study were two-fold: (1) To determine if species identified in ethnopharmacological field studies as having traditional uses for skin and soft tissue infection (SSTI) exhibit significantly more activity against P. acnes than species with no such reported use; and (2) Chemically characterize active extracts and assess their suitability for future investigation. Extracts of Italian medicinal (for acne and other skin infection) and randomly collected plants and fungi were screened for growth-inhibitory and anti-biofilm activity in P. acnes using broth microdilution methods. Bioactive extracts were chemically characterized by HPLC and examined for cytotoxicity against human keratinocytes (HaCaTs). Following evaluation of 157 extracts from 10 fungi and 58 plants, we identified crude extracts from seven species exhibiting growth inhibitory activity (MICs 64–256 μg mL⁻¹). All active extracts were examined for cytotoxicity against HaCaTs; extracts from one fungal and one plant species were toxic (IC₅₀ 256 μg mL⁻¹). HPLC analysis with chemical standards revealed many of these extracts contained chlorogenic acid, p-coumaric acid, ellagic acid, gallic acid, and tannic acid. In conclusion, species used in traditional medicine for the skin exhibited significantly greater (p < 0.05) growth inhibitory and biofilm eradication activity than random species, supporting the validity of an ethnobotanical approach to identifying new therapeutics. The anti-acne activity of three extracts is reported for the first time: Vitis vinifera leaves, Asphodelus microcarpus leaves, and Vicia sativa aerial parts.

Understanding the role of Propionibacterium acnes in acne vulgaris: The critical importance of skin sampling methodologies

Acne vulgaris is a chronic inflammatory skin condition classified by the Global Burden of Disease Study as the eighth most prevalent disease worldwide. The pathophysiology of the condition has been extensively studied, with an increase in sebum production, abnormal keratinization of the pilosebaceous follicle, and an inflammatory immune response all implicated in its etiology. One of the most disputed points, however, is the role of the gram-positive anaerobic bacterium Propionibacterium acnes in the development of acne, particularly when this organism is also found in normal sebaceous follicles of healthy skin. Against this background, we now describe the different sampling strategies that have been adopted for qualitative and quantitative study of P acnes within intact hair follicles of the skin and discuss the strengths and weaknesses of such methodologies for investigating the role of P acnes in the development of acne.

Three dimensional distribution of Propionibacterium acnes biofilms in human skin

Propionibacterium acnes is regarded as a common member of the human skin microbiota, often occurring in biofilms. Little is known about the size of bacterial biofilms in hair follicles as a few sections of biopsy tissue are routinely evaluated. Transversal sectioning provides a better opportunity for histological analyses of hair follicles which can be followed through the different morphological levels. Direct visualization of P. acnes biofilms in hundreds of consecutive sections allowed insight into the 3D distribution in human hair follicles as well as investigating the depth of biofilm distribution within hair follicles. Four distinct colonization patterns of P. acnes biofilms were revealed. Results have shown that an individual P. acnes biofilm can spread for 1900 μm in a terminal hair follicle. This information can be of help while designing potential antibiofilm treatment.

Impetigo - review

Impetigo is a common cutaneous infection that is especially prevalent in children. Historically, impetigo is caused by either group A β-hemolytic streptococci or Staphylococcus aureus. Currently, the most frequently isolated pathogen is S. aureus. This article discusses the microbiologic and virulence factors of group A β-hemolytic streptococci and Staphylococcus aureus, clinical characteristics, complications, as well as the approach to diagnosis and management of impetigo. Topical agents for impetigo therapy are reviewed.

Photodynamic inactivation of biofilm: taking a lightly colored approach to stubborn infection

Microbial biofilms are responsible for a variety of microbial infections in different parts of the body, such as urinary tract infections, catheter infections, middle-ear infections, gingivitis, caries, periodontitis, orthopedic implants, and so on. The microbial biofilm cells have properties and gene expression patterns distinct from planktonic cells, including phenotypic variations in enzymic activity, cell wall composition and surface structure, which increase the resistance to antibiotics and other antimicrobial treatments. There is consequently an urgent need for new approaches to attack biofilm-associated microorganisms, and antimicrobial photodynamic therapy (aPDT) may be a promising candidate. aPDT involves the combination of a nontoxic dye and low-intensity visible light which, in the presence of oxygen, produces cytotoxic reactive oxygen species. It has been demonstrated that many biofilms are susceptible to aPDT, particularly in dental disease. This review will focus on aspects of aPDT that are designed to increase efficiency against biofilms modalities to enhance penetration of photosensitizer into biofilm, and a combination of aPDT with biofilm-disrupting agents.

Salivary epithelial cells as model to study immune response against cutaneous pathogens

The human skin not only provides passive protection as a physical barrier against external injury, but also mediates active surveillance via epidermal cell surface receptors that recognize and respond to potential invaders. Primary keratinocytes and immortalized cell lines, the commonly used sources to investigate immune responses of cutaneous epithelium are often difficult to obtain and/or potentially exhibit changes in cellular genetic make-up. Here we investigated the possibility of using salivary epithelial cells (SEC) to evaluate the host response to cutaneous microbes. Elevated secretion of IFN-γ and IL-12 was observed in the SEC stimulated with Staphylococcus aureus, a transient pathogen of the skin, as mono species biofilm as compared to SEC stimulated with a commensal microbe, the Staphylococcus epidermidis. Co-culture of the SEC with both microbes as dual species biofilm elicited maximum cytokine response. Stimulation with S. aureus alone but not with S. epidermidis alone induced maximum toll-like receptor-2 (TLR-2) expression in the SEC. Exposure to dual species biofilm induced a sustained upregulation of TLR-2 in the SEC for up to an hour. The data support novel application of the SEC as efficient biospecimen that may be used to investigate personalized response to cutaneous microflora.

Mucosal biofilm detection in chronic otitis media: a study of middle ear biopsies from Greenlandic patients

The objectives of this study were to examine middle ear biopsies from Greenlandic patients with chronic otitis media (COM) for the presence of mucosal biofilms and the bacteria within the biofilms. Thirty-five middle ear biopsies were obtained from 32 Greenlandic COM patients admitted to ear surgery. All biopsies were examined by means of peptide nucleic acid-fluorescent in situ hybridization (PNA-FISH), and if possible culture and polymerase chain reaction (PCR) of the 16s rDNA and sequencing. Light microscopy and confocal laser scanning microscopy were used. Skin biopsies from 23 of the patients served as controls. PNA-FISH showed morphological signs of biofilms in 15 out of 35 (43 %) middle ear biopsies. In the control skin biopsies, there were signs of biofilms in eight out of 23 biopsies (30 %), probably representing skin flora. PCR and 16s sequencing detected bacteria in seven out of 20 (35 %) usable middle ear biopsies, and in two out of ten (20 %) usable control samples. There was no association between biofilm findings and PCR and 16s sequencing. Staphylococci were the most common bacteria in bacterial culture. We found evidence of bacterial biofilms in 43 % of middle ear biopsies from patients COM. The findings may indicate that biofilms are a part of the pathogenesis in recurrent episodes of ear discharge in COM, but further investigations are necessary.

Emergence of the epidemic methicillin-resistant Staphylococcus aureus strain USA300 coincides with horizontal transfer of the arginine catabolic mobile element and speG-mediated adaptations for survival on skin

The arginine catabolic mobile element (ACME) is the largest genomic region distinguishing epidemic USA300 strains of methicillin-resistant Staphylococcus aureus (MRSA) from other S. aureus strains. However, the functional relevance of ACME to infection and disease has remained unclear. Using phylogenetic analysis, we have shown that the modular segments of ACME were assembled into a single genetic locus in Staphylococcus epidermidis and then horizontally transferred to the common ancestor of USA300 strains in an extremely recent event. Acquisition of one ACME gene, speG, allowed USA300 strains to withstand levels of polyamines (e.g., spermidine) produced in skin that are toxic to other closely related S. aureus strains. speG-mediated polyamine tolerance also enhanced biofilm formation, adherence to fibrinogen/fibronectin, and resistance to antibiotic and keratinocyte-mediated killing. We suggest that these properties gave USA300 a major selective advantage during skin infection and colonization, contributing to the extraordinary evolutionary success of this clone.

IMPORTANCE

Over the past 15 years, methicillin-resistant Staphylococcus aureus (MRSA) has become a major public health problem. It is likely that adaptations in specific MRSA lineages (e.g., USA300) drove the spread of MRSA across the United States and allowed it to replace other, less-virulent S. aureus strains. We suggest that one major factor in the evolutionary success of MRSA may have been the acquisition of a gene (speG) that allows S. aureus to evade the toxicity of polyamines (e.g., spermidine and spermine) that are produced in human skin. Polyamine tolerance likely gave MRSA multiple fitness advantages, including the formation of more-robust biofilms, increased adherence to host tissues, and resistance to antibiotics and killing by human skin cells.

The immunomodulatory activity of Staphylococcus aureus products derived from biofilm and planktonic cultures

Biofilms are probably one of the most common structures formed by microorganisms in various environments. The higher resistance of such microbial communities to stress conditions, including antibiotics and host immune response, is recently extensively studied. However, the weak activity of phagocytic cells against microbial biofilm is not yet fully understood and explained. The aim of this study was: (1) a qualitative and quantitative comparison of cell components/products released from Staphylococcus aureus biofilm or planktonic cultures, (2) evaluation of the influence of such cell components/products on murine leukocytes secretory function. For this, mouse peritoneal leukocytes were stimulated with biofilm or planktonic staphylococcal cultures or their acellular filtrates, and then the production of cytokines (TNF-α, IL-6, IL-10, MCP-1 and MIP-1α), hemolytic activity and staphylokinase (SAK) production was determined. It was found that similar staphylococcal components/products possessing the immunomodulatory properties, were present in both, biofilm and planktonic filtrates. Moreover, these compounds were similarly active in the stimulation of TNF-α and MCP-1 release from leukocytes. The hemolytic activity and SAK release by planktonic and biofilm cultures were also comparable. What is interesting, stronger stimulatory activity of biofilm-derived components/products of clinical S. aureus strains in the case of MIP-1α, IL-6 and IL-10 was noticed. On the other hand, taking into consideration the reference strains, MIP-1α production was enhanced by “planktonic filtrates”. Thus, in our study it was proved, first of all, that biofilm is not a structure fully separated from the external environment. Second, the influence of these S. aureus constituents/metabolites on leukocytes seems to be more strain-dependent than culture phenotype-dependent. The lack of one common profile of biofilm and planktonic S. aureus cultures/filtrates biological activity indicates that the disturbances in cytokines’ production could not be the only reason for the so-called “frustrated phagocytosis”, connected with enhanced biofilm resistance.

Propionibacterium acnes: an update on its role in the pathogenesis of acne

In recent years, significant progress has been made in the understanding of the pathophysiological mechanisms of acne and the role of Propionibacterium acnes. With this review, the authors aim to provide an update on the current understanding of the role of P. acnes in the development of acne lesions and analysing the potential implications for future treatments. A total of 188 articles published between January 1980 and March 2013 were searched using key words such as acne, P. acnes, microbiology, Corynebacterium acnes, acne vulgaris, pathogenesis, antibiotic, vaccination and a combination of those key words. From those articles, 77 were analysed in depth. Recent data confirm that P. acnes has a strong proinflammatory activity and targets molecules involved in the innate cutaneous immunity, keratinocytes and sebaceous glands of the pilosebaceous follicle and leads to the development of comedones. Furthermore, the profile of its different strains may differ between healthy subjects and acne patients. The better understanding of the role of P. acnes may allow for new perspectives in the treatment of acne. Novel therapies should target molecules implicated in the activation of innate immunity, including toll-like receptors, protease-activated receptors and topical antimicrobial peptides; the latter may be an alternative to topical antibiotics and thus a solution for limiting bacterial resistance induced by topical macrolides. Vaccines may also be promising. However, the most appropriate candidate remains to be selected.

Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: risk to recipients with thermal injury

The previous use of fresh porcine xenografts at the Prague Burn Centre had raised concerns over the transmission of zoonotic pathogens. This study examines the risk of zoonotic Staphylococcus aureus colonisation of burn patients from fresh porcine skin xenografts. Samples were collected from the nares, skin and perineum of commercial pigs (n=101) and were screened for methicillin sensitive S. aureus (MSSA) and resistant S. aureus (MRSA). The efficacy of the antibiotic wash used in decontamination of the pigskin was tested against planktonic- and biofilm-grown isolates. The spa type of each isolate was also confirmed. All pig swabs were negative for MRSA but 86% positive for MSSA. All planktonic-grown isolates of MSSA were sensitive to chloramphenicol and nitrofurantoin and 44% of isolates were resistant to streptomycin. Isolates grown as biofilm exhibited higher rates of antimicrobial resistance. Sequence analysis revealed three distinct spa types of the MRSA ST398 clonal type. This finding demonstrates the existence of a MSSA reservoir containing spa types resembling those of well-known MRSA strains. These MSSA exhibit resistance to antibiotics used for decontamination of the pigskin prior to xenograft. Amended use of procurement could allow the use of fresh pigskin xenografts to be reinstated.

Wound biofilms: lessons learned from oral biofilms

Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque, are a primary cause of oral diseases including caries, gingivitis, and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible; thus, biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well elucidated. In contrast, wound research has relatively recently directed attention to the role biofilms have in chronic wounds. This review discusses the biofilms in periodontal disease and chronic wounds with comparisons focusing on biofilm detection, biofilm formation, the immune response to biofilms, bacterial interaction, and quorum sensing. Current treatment modalities used by both fields and future therapies are also discussed.

In vitro determination of the antibiotic susceptibility of biofilm-forming Pseudomonas aeruginosa and Staphylococcus aureus: possible role of proteolytic activity and membrane lipopolysaccharide

We carried out a comprehensive overview of inhibitory effects of selected antibiotics on planktonic and biofilm cells of Staphylococcus aureus (ATCC 29213) and Pseudomonas aeruginosa (ATCC 27853) strains. The possible involvement of protease activity and the lipopolysaccharide (LPS) profile of P. aeruginosa were also analyzed. Biofilm cells of both strains were more resistant to antibiotics than their planktonic counterparts. Protease activity was increased in both strains in the biofilm forms. Challenge with sublethal doses of antibiotics also increased proteolytic activity of biofilm cells. Additionally, the LPS profile of P. aeruginosa showed pattern alterations of the biofilm that can contribute to biofilm resistance and survival. These observations provide evidence for the involvement of bacterial proteolytic activity and LPS profile in the resistance of biofilm bacteria to antibiotics compared to their planktonic counterparts.

First evidence of bacterial biofilms in the anaerobe part of scalp hair follicles: a pilot comparative study in folliculitis decalvans

BACKGROUND

The cause of folliculitis decalvans (FD) remains unknown. We hypothesized that a bacterial biofilm could be involved in its pathogenesis.

OBJECTIVE

To assess the presence or not of a bacterial biofilm in the hair roots of the scalp in FD.

PATIENTS AND METHODS

Hairs plucked from four patients and three controls were examined by field emission scanning electron microscopy (FESEM) and confocal laser scanning microscopy (CLSM).

RESULTS

Bacterial communities organized as biofilms were observed both by FESEM and CLSM in the under infundibular part of hair follicles in all patients and in two of the three controls. In patients and controls, these biofilms were formed exclusively of bacilli of comparable shapes.

CONCLUSION

This pilot study provides the first evidence of the presence of bacterial biofilms in the infra infundibular part of human scalp hair follicles. These biofilms were detected both in FD patients and controls, suggesting their ubiquity as a commensal biofilm with a possible pathogenic shift in FD.

Dimethyl sulfoxide enhances effectiveness of skin antiseptics and reduces contamination rates of blood cultures

Effective skin antisepsis is of central importance in the prevention of wound infections, colonization of medical devices, and nosocomial transmission of microorganisms. Current antiseptics have a suboptimal efficacy resulting in substantial infectious morbidity, mortality, and increased health care costs. Here, we introduce an in vitro method for antiseptic testing and a novel alcohol-based antiseptic containing 4 to 5% of the polar aprotic solvent dimethyl sulfoxide (DMSO). The DMSO-containing antiseptic resulted in a 1- to 2-log enhanced killing of Staphylococcus epidermidis and other microbes in vitro compared to the same antiseptic without DMSO. In a prospective clinical validation, blood culture contamination rates were reduced from 3.04% for 70% isopropanol-1% iodine (control antiseptic) to 1.04% for 70% isopropanol-1% iodine-5% DMSO (P < 0.01). Our results predict that improved skin antisepsis is possible using new formulations of antiseptics containing strongly polarized but nonionizing (polar aprotic) solvents.

Pityriasis amiantacea: a distinctive presentation of psoriasis associated with tumour necrosis factor-α inhibitor therapy

Pityriasis amiantacea (PA; also known as tinea amiantacea) is a relatively rare but distinctive scalp condition characterized by thick scales that adhere to each other and to the hair shaft, resulting in agglomeration and matting of hair. Temporary alopecia is a common complication. Although a specific cause remains unclear, PA is associated with several inflammatory diseases such as psoriasis and seborrhoeic dermatitis. We present a case of PA as a complication of underlying psoriasis, which developed during tumour necrosis factor (TNF)-α inhibitor therapy for Crohn disease. This paradoxical cutaneous reaction to anti-TNF-α therapy has been recently described as an emerging and perplexing cause of psoriasis and psoriasiform eruptions.