Genotypic and phenotypic characterization of Staphylococcus aureus strains isolated in subjects with atopic dermatitis. Higher prevalence of exfoliative B toxin production in lesional strains and correlation between the markers of disease intensity and colonization density

Relationship between the Polymer Blend Using Chitosan, Polyethylene Glycol, Polyvinyl Alcohol, Polyvinylpyrrolidone, and Antimicrobial Activities against Staphylococcus aureus

The findings from Pareto charts, main effect plots, and interaction plots demonstrate the importance of polymer concentration. Increasing concentration improves the inhibition percentage and decreases the MIC50. However, the primary factor that influences these changes is chitosan (CS). Additionally, the interaction between CS and PVP, along with other polymers, plays a crucial role in achieving better antimicrobial effects. These results enhance our understanding of the antimicrobial properties of the studied polymers and offer valuable insights for developing effective antimicrobial formulations. The MIC50 value of M1-M16 was at a polymer percentage of 12.5%. At 12.5% polymer percentage, with the limits of [PVA], [PEG], and [PVP] being 0.002-0.004 g/mL and [CS] being 0.001-0.002 g/mL, using the 2-level full factorial method, the inhibition percentage is equal to 174.1 - 27,812 PVA - 18,561 PVP - 25,960 PEG - 38,752 CS + 9,263,047 PVA*PVP + 10,430,763 PVA*PEG + 15,397,157 PVA*CS + 7,088,313 PVP*PEG + 7,841,221 PVP*CS + 14,228,046 PEG*CS - 3,367,292,860 PVA*PVP*PEG - 5,671,998,721 PVA*PVP*CS - 6,619,041,275 PVA*PEG*CS - 3,917,095,529 PVP*PEG*CS + 2,273,661,969,470 PVA*PVP*PEG*CS. Theoretically, the most economical concentrations of PVA, PVP, PEG, and CS are 0.002, 0.002, 0.002, and 0.001 mg/mL at a concentration of 12.5% to reach an inhibition percentage of 99.162%, which coincides with the MBC value.

Atopic dermatitis-derived Staphylococcus aureus strains: what makes them special in the interplay with the host

Background

Atopic dermatitis (AD) is a chronic inflammatory skin condition whose pathogenesis involves genetic predisposition, epidermal barrier dysfunction, alterations in the immune responses and microbial dysbiosis. Clinical studies have shown a link between Staphylococcus aureus and the pathogenesis of AD, although the origins and genetic diversity of S. aureus colonizing patients with AD is poorly understood. The aim of the study was to investigate if specific clones might be associated with the disease.

Methods

WGS analyses were performed on 38 S. aureus strains, deriving from AD patients and healthy carriers. Genotypes (i.e. MLST, spa-, agr- and SCCmec-typing), genomic content (e.g. virulome and resistome), and the pan-genome structure of strains have been investigated. Phenotypic analyses were performed to determine the antibiotic susceptibility, the biofilm production and the invasiveness within the investigated S. aureus population.

Results

Strains isolated from AD patients revealed a high degree of genetic heterogeneity and a shared set of virulence factors and antimicrobial resistance genes, suggesting that no genotype and genomic content are uniquely associated with AD. The same strains were characterized by a lower variability in terms of gene content, indicating that the inflammatory conditions could exert a selective pressure leading to the optimization of the gene repertoire. Furthermore, genes related to specific mechanisms, like post-translational modification, protein turnover and chaperones as well as intracellular trafficking, secretion and vesicular transport, were significantly more enriched in AD strains. Phenotypic analysis revealed that all of our AD strains were strong or moderate biofilm producers, while less than half showed invasive capabilities.

Conclusions

We conclude that in AD skin, the functional role played by S. aureus may depend on differential gene expression patterns and/or on post-translational modification mechanisms rather than being associated with peculiar genetic features.

Evaluation of cutaneous, oral and intestinal microbiota in patients affected by pemphigus and bullous pemphigoid: A pilot study

BACKGROUND

Significant alterations of the cutaneous microbiota (CM) have been recently demonstrated in bullous pemphigoid (BP). Microbiome data of both oral cavity (OM) and gut (GM) from patients affected by bullous disease are not available yet and, further consistent studies focused on the role of such microbial populations are still missing.

OBJECTIVE

Objective: In this pilot study we characterized and compared GM, OM and CM of patients affected by pemphigus vulgaris (PV) and BP to investigate a distinctive microbiome composition in this two rare dermatological disorders.

METHODS

High-throughput sequencing of the V1-V3 hyper-variable regions of 16S rRNA was used to compare the bacterial community composition of stool, skin and oral mucosae swabs in a cohort of PV and BP patients. A dedicated bioinformatics software coupled with in-house pipeline was implemented to analyse and compare diseases dataset.

RESULTS

GM samples of both PV and BP patients were principally characterized by Firmicutes and Bacteroidetes phyla. Interestingly, the Firmicutes phylum and Staphylococcus genus were mainly represented in cutaneous samples. The diversity of phyla in oral mucosae was higher than those of gut and skin samples and, Bacteroidetes phylum was significantly underrepresented in all PV samples.

CONCLUSION

Firmicutes phylum and Staphilococcus genus were the most represented in OM and CM swabs of PV and BP microbial populations. Moreover, we argue the quantitative imbalance linked to the decrease of Bacteriodetes in the oral cavity of PV patients might be associated to disease typical fetor. To shed light on this peculiar feature further studies are still required.

Computational structural and functional analysis of hypothetical proteins of Staphylococcus aureus

Genome sequencing projects has led to an explosion of large amount of gene products in which many are of hypothetical proteins with unknown function. Analyzing and annotating the functions of hypothetical proteins is important in Staphylococcus aureus which is a pathogenic bacterium that cause multiple types of diseases by infecting various sites in humans and animals. In this study, ten hypothetical proteins of Staphylococcus aureus were retrieved from NCBI and analyzed for their structural and functional characteristics by using various bioinformatics tools and databases. The analysis revealed that some of them possessed functionally important domains and families and protein-protein interacting partners which were ABC transporter ATP-binding protein, Multiple Antibiotic Resistance (MAR) family, export proteins, Helix-Turn-helix domains, arsenate reductase, elongation factor, ribosomal proteins, Cysteine protease precursor, Type-I restriction endonuclease enzyme and plasmid recombination enzyme which might have the same functions in hypothetical proteins. The structural prediction of those proteins and binding sites prediction have been done which would be useful in docking studies for aiding in the drug discovery.

A novel method to control the balance of skin microflora

BACKGROUND

It is recognized that colonization by Staphylococcus aureus (SA) on the skin is one of the factors that can worsen atopic dermatitis (AD). Antibiotics and germicides are not the best choice to remove bacteria from the skin of AD patients, because of problems of irritation to the skin and bacterial resistance. We therefore turned our attention to the biofilm of SA with the aim of removing only SA from the skin surface of AD patients. We found that xylitol (X) and farnesol (F) synergistically inhibited biofilm formation by SA and dissolved biofilm formed in vivo (Part 1).

OBJECTIVE

To test whether application of AD for 1 week with FX cream can reduce SA without affecting Staphylococcus epidermidis.

METHODS

A randomized, double-blind, placebo-controlled right-and-left comparison study was performed. The arms of 17 patients with dry-type AD were applied with skin-care cream including/or not including a 0.02% F and 5% X combination for 1 week. The clinical response, biophysical assessment of the skin surface and counts of skin microflora were recorded before and after 1 week of therapy.

RESULTS

The ratio of SA in total bacteria at sites to which FX cream had been applied was significantly decreased after 1 week (P = 0.007), compared with before application and with placebo sites (P = 0.045). The mean skin conductance (a parameter indicating the state of hydration of the skin surface) of FX cream sites was increased significantly compared with the conductance before application (P = 0.0001) and at placebo sites (P = 0.002).

CONCLUSION

This study provides evidence supporting the idea that cream containing F and X is a useful skin-care agent for atopic dry skin colonized by SA.

A novel method to control the balance of skin microflora

BACKGROUND

Staphylococcus aureus (SA) is usually present in atopic dry skin, and not only in regions seriously affected by atopic dermatitis. SA discharges various toxins and enzymes that injure the skin, and forms a biofilm from fibrin fiber and glycocalyx; the biofilm is important for adhesion of SA to the skin and for resistance to anti-microbial agents. Even highly effective moisturizers do not work perfectly on atopic dry skin. Staphylococcus epidermidis (SE) is a major constituent of skin microflora on healthy human skin, and provides protection against the growth of pathogenic bacteria.

OBJECTIVES

Since treatment with anti-microbials may lead to re-growth of SA, which grows faster than other Staphylococci and often shows antibiotic resistance, we searched for novel approaches to control the skin-microfloral balance without using conventional anti-microbials.

METHOD

Biofilm formation by SA in vitro was observed in detail using scanning electron microscopy. Approximately 500 substances were screened for a selective effect on SA growth and SA biofilm.

RESULTS

We found that xylitol inhibited the formation of glycocalyx, and farnesol dissolved fibrin fibers. Farnesol suppressed the growth of only SA, and did not affect that of SE. Xylitol and farnesol synergistically inhibited biofilm formation by SA.

CONCLUSION

Xylitol and farnesol have potential for controlling the skin-microfloral balance because of their selective effects and inhibition of biofilm formation. They might provide a useful and safe method to care for skin colonized by SA, without using antibiotics.

Presence of staphylococcal exfoliative toxin A in sera of patients with atopic dermatitis

BACKGROUND

It has been reported that the toxins that Staphylococcus aureus produces are associated with the exacerbation of atopic dermatitis (AD). It has been shown in many studies that staphylococcal enterotoxin (SE) A and SEB contribute to AD by humoral immunity through IgE production as a superantigen. On the other hand, little attention has been paid to the relationship between AD and exfoliative toxin x (ETx).

OBJECTIVE

We investigated the toxins that are frequently detected from the skin of patients and how these toxins affect AD.

METHODS

S. aureus, isolated from the skin of 100 patients with mild to severe AD, were examined for the producibility of toxins by polymerase chain reaction. Serum samples were obtained from 21 patients with mild and moderate AD. The levels of SEB, ETA, total IgE, specific IgE, and specific IgG in sera were measured by ELISA.

RESULTS

SEB was most frequently detected from S. aureus on the skin of these patients as previously reported. And ETx, to which little attention has been paid so far, was frequently detected next to SEB. Furthermore, ETA was detected from the sera of almost all the AD patients. SEB was not detected at all. Although the level of ETA in the AD group was significantly higher than that of controls, ETA-specific IgE was not detected from their sera. High levels of ETA tended to be detected from infantile patients. Although there were no significant differences in the levels of ETA-IgG between AD and the controls, its prevalence was more than twice as high as the controls in AD.

CONCLUSION

These results suggest that many AD patients were exposed to ETx. We conclude that ETx may contribute to exacerbation of AD, particularly in infants, by a mechanism that is not through specific IgE production, unlike SEB.

Severity of nonbullous Staphylococcus aureus impetigo in children is associated with strains harboring genetic markers for exfoliative toxin B, Panton-Valentine leukocidin, and the multidrug resistance plasmid pSK41

Nonbullous impetigo is a common skin infection in children and is frequently caused by Staphylococcus aureus. Staphylococcal toxins and especially exfoliative toxin A are known mediators of bullous impetigo in children. It is not known whether this is also true for nonbullous impetigo. We set out to analyze clonality among clinical isolates of S. aureus from children with nonbullous impetigo living in a restricted geographical area in The Netherlands. We investigated whether staphylococcal nasal carriage and the nature of the staphylococcal strains were associated with the severity and course of impetigo. Bacterial isolates were obtained from the noses and wounds of children suffering from impetigo. Strains were genetically characterized by pulsed-field gel electrophoresis-mediated typing and binary typing, which was also used to assess toxin gene content. In addition, a detailed clinical questionnaire was filled in by each of the participating patients. Staphylococcal nasal carriage seems to predispose the patients to the development of impetigo, and 34% of infections diagnosed in the Rotterdam area are caused by one clonal type of S. aureus. The S. aureus strains harbor the exfoliative toxin B (ETB) gene as a specific virulence factor. In particular, the numbers (P = 0.002) and sizes (P < 0.001) of the lesions were increased in patients infected with an ETB-positive strain. Additional predictors of disease severity and development could be identified. The presence of a staphylococcal plasmid encoding multiple antibiotic resistance traits, as detected by binary typing, was associated with a reduction in the cure rate. Our results recognize that a combination of staphylococcal virulence and resistance genes rather than a single gene determines the development and course of nonbullous impetigo. The identification of these microbial genetic markers, which are predictive of the severity and the course of the disease, will facilitate guided individualized antimicrobial therapy in the future.

Staphylococcal epidermolysins

PURPOSE OF REVIEW

Staphylococcal epidermolysins are the major causative toxins of bullous impetigo and staphylococcal scalded skin syndrome. This disease is characterized by the splitting of the epidermis between two cell layers resulting in exfoliation. It predominantly affects newborn babies and exposes them to secondary infections. This leads to the risk of epidemics, especially in nurseries. With only an experimental model which consists of skin injections in newborn mice and the recent determination of three-dimensional structures, the essential function of these toxins remained controversial, split between that of specific proteases and that of superantigens.

RECENT FINDINGS

Staphylococcal epidermolysins now constitute a family of toxins, with the recent characterizations of two new serotypes: ETC and ETD. They may be secreted by sensitive or methicillin-resistant strains. Four molecules were also identified in Staphylococcus hyicus responsible for exudative epidermitis in swine. While different observations suggested a proteolytic action to these toxins, the histological parallel made with pemphigus foliaceus greatly helped in the characterization of the targets for epidermolysins ETA, ETB, ETD: desmoglein-1, a desmosome-constitutive protein, and incidentally melanocyte-stimulating hormones, which accounts for the blisters observed clinically.

SUMMARY

The growing complexity in staphylococcal toxins has to be taken into account both for their association with diseases and for diagnosis purposes. Even though cases of staphylococcal scalded skin syndrome in adults are rare, they raise further questions about the pathogenic features of the disease such as individual sensitivity and distribution of the toxins into the body.