Prevalence of producers of enterotoxins and toxic shock syndrome toxin-1 among Staphylococcus aureus strains isolated from atopic dermatitis lesions

The Role of Immune Defects and Colonization of Staphylococcus aureus in the Pathogenesis of Atopic Dermatitis

Atopic dermatitis (AD) is a condition with a complex and not fully understood etiology. In patients with AD, acute skin lesions are colonized by a greater number of Staphylococcus aureus (S. aureus) bacteria than chronic lesions, clinically unchanged atopic skin, or the skin of healthy people. Mechanisms promoting skin colonization by S. aureus include complex interactions among several factors. Apart from increased adhesion of S. aureus in atopic skin, defects of the innate immune response resulting in the lack of restriction of the growth of microorganisms also contribute to susceptibility to colonization by and infection with S. aureus. A deficiency in the endogenous antimicrobial peptides may be partly responsible for the susceptibility to colonization by and skin infection with S. aureus in patients with AD. Majority of isolated S. aureus stains are able to produce exotoxins, which act as superantigens. Moreover, anti-S. aureus-specific IgE was identified and measured in patients with AD, revealing that its level corresponds to the severity of the disease. This review of the literature attempts to identify factors that are involved in the pathogenesis of AD-related S. aureus skin colonization. In the light of presented mechanisms, a reduction of colonization may become both causative and symptomatic treatment in AD.

Chronic Sinusitis with Nasal Polyps: Staphylococcal Exotoxin Immunoglobulin E and Cellular Inflammation

Background

The etiology of chronic sinusitis with nasal polyposis (CS/NP) remains enigmatic. Frequently, Staphylococcus aureus is present in the nose of CS/NP patients, although the significance is unclear. Recent reports have suggested the hypothesis that these bacteria may secrete exotoxins triggering the inflammatory mucosal changes seen in CS/NP. This mechanism of immunopathology has been established in other diseases associated with Staphylococcus colonization and exotoxin secretion such as atopic dermatitis. In atopic dermatitis, the exotoxins incite a local superantigen response in which clonal T-cell activation and massive cytokine release occur in the affected skin. Second, these exotoxins can act as traditional allergens, stimulating a typical immunoglobulin E (IgE) response in the serum, which has been correlated with disease severity. This study is designed to begin the assessment of the hypothesis that a similar mechanism takes place in CS/NP.

Methods

Serum was drawn from patients with CS/NP undergoing endoscopic sinus surgery as well as 13 atopic and nonatopic control subjects without sinusitis. IgE levels to S. aureus exotoxins A (SEA), SE exotoxins B (SEB), and toxic shock syndrome toxin 1 were measured using enzyme-linked immunosorbent assay. Tissue eosinophilia and the presence of lymphocytes on hemotoxylin and eosin-stained sections of polyps were scored by a blinded pathologist and correlated to presence of toxin IgE in the serum.

Results

Staphylococcal exotoxin (SE)-specific IgE was found in the serum of 5/10 (50%) of the patients with CS/NP. In contrast, 0/13 control patients had IgE to the exotoxins (p = 0.031). Polyp eosinophil, lymphocyte, and mononuclear cell counts were compared in IgE exotoxin-positive and -negative subjects. A trend toward increased eosinophil counts in patients with SE IgE (SE IgE+) was present, but not statistically significant.

Conclusion

These results indicate that a high percentage of CS/NP patients show a systemic IgE response to S. aureus exotoxins in comparison with controls without CS/NP. Although these results are consistent with the actions of Staphylococcus toxins in other diseases, additional work is necessary to establish a local superantigen response in the nasal mucosa of CS/NP patients. (American Journal of Rhinology 18, 273–278, 2004)

Presence and Characterization of Sensitization to Staphylococcal Enterotoxins in Patients with Allergic Rhinitis

Exotoxins derived from Staphylococcus aureus appear to be involved in the pathogenesis of allergic diseases, especially atopic dermatitis (AD). However, little is known about sensitization to enterotoxins in cases of respiratory allergies. Because the nasal cavity is a primary site of colonization by S. aureus, we sought to determine the prevalence and role of serum immunoglobulin E (IgE) antibodies against staphylococcal enterotoxin A (SEA) and SEB in patients with allergic rhinitis (AR). The presence of SEA- and SEB-specific IgE was determined in 40 patients with AR and 16 healthy control subjects. In the rhinitis group, nasal symptom score, total serum IgE, sensitization to other inhaled allergens and the presence of sinusitis were determined. Twenty-five percent of patients with AR were sensitized to SEA/SEB whereas 6.3% of controls were sensitized to the toxins. Sensitization to SEB was predominant relative to SEA. There were no significant differences in the severity of nasal symptoms and complications of other allergic diseases including AD and bronchial asthma, between patients with or without sensitization to SEA/SEB. However, patients sensitized to these toxins were likely to show increased total serum IgE and polyvalent sensitization, suggesting that exposure and subsequent sensitization to SEA/SEB may be involved in polyvalent sensitization.

The microbiome and atopic eczema: More than skin deep

Discoveries in the defective molecular composition of the epidermal barrier, such as the epidermal protein filaggrin, in those with atopic eczema (or atopic dermatitis [AD]) have proved crucial in understanding this disease, but its aetiology remains to be fully elucidated. The epidermal barrier is just one interface between the microbial world and our immune system. Recent advances in molecular technology have demonstrated for the first time the true scale of the normal human microbiome and changes seen in disease states. In this review article we discuss the role of the human microbiome in the aetiology and maintenance of AD. The role of Staphylococcus aureus within the skin microbiome is examined, in addition to the role of other bacteria and fungi, identified using novel culture-independent methods. The significant contribution of the gut microbiome and its manipulation via probiotic use is also reviewed. We emphasise that the microbiome of separate systems, including the gut, has a significant role to play in the manifestation of this cutaneous disorder. To date, there has been a lack of studies investigating whether changes to the lung microbiome may play a role in AD. An early interaction between the microbiome and immune system via multiple routes (skin-gut-lung) could feasibly affect the risk of a subsequent development of atopic diseases. When making management decisions for AD patients, clinicians must be mindful of the role of the microbiome.

Past, present, and future for biologic intervention in atopic dermatitis

Atopic dermatitis (AD) is a debilitating disease that significantly alters the quality of life for one in four children and one in 10 adults. Current management of AD utilizes combinations of treatments to symptomatically alleviate disease by suppressing the inflammatory response and restoring barrier function in the skin, reducing disease exacerbation and flare, and preventing secondary skin infections. Resolution is temporary and long-term usage of these treatments can be associated with significant side-effects. Antibody therapies previously approved for inflammatory diseases have been opportunistically evaluated in patients with atopic dermatitis; however, they often failed to demonstrate a significant clinical benefit. Monoclonal antibodies currently in development offer hope to those individuals suffering from the disease by specifically targeting immune and molecular pathways important for the pathogenesis of atopic dermatitis. Here, we review the underlying biological pathways and the state of the art in therapeutics in AD.

The role of antiseptic agents in atopic dermatitis

The skin of individuals with atopic dermatitis has a susceptibility to be colonized with Staphylococcus aureus. This has been associated with increased frequency and severity of exacerbations of atopic dermatitis. Therefore, there is a growing interest in the use of antiseptic agents to target primary bacterial colonization and infection. Antiseptic agents have been found to be better tolerated and less likely to induce bacterial resistance as compared to antibiotics. There is also a wide variety of antiseptic agents available. The efficacy of antiseptic agents has yet to be established as the studies reviewed previously have been small and of suboptimal quality. This review discusses the rationale behind targeting S. aureus with antiseptic agents and presents findings from a review of studies assessing the efficacy of antiseptics in atopic dermatitis in the last five years. Four studies were found, including a bleach bath study which has already been reviewed elsewhere. The remaining 3 studies assessed the efficacy of sodium hypochlorite containing cleansing body wash, sodium hypochlorite baths and 1% triclosan in leave on emollient. These studies suggested some benefit for the inclusion of antiseptic use with the mainstay management of atopic dermatitis, including a potential steroid sparring effect. However, there are many limitations to these studies which therefore warrant further investigation on the impact of antiseptic use in atopic dermatitis.

A diversity profile from the staphylococcal community on atopic dermatitis skin: a molecular approach

AIMS

The aim of this study was to determine the biodiversity of the skin staphylococcal community from patients with atopic dermatitis (AD) and superantigen (SAg) detection from Staphylococcus aureus isolates.

METHODS AND RESULTS

In this study, we developed a novel multiplex PCR that allows the identification and discrimination of bacteria belonging to the Staphylococcus genus both Staph. aureus and coagulase-negative Staphylococcus - Staph. capitis, Staph. epidermidis, Staph. haemolyticus and Staph. hominis isolated from the skin of patients with AD. In addition, a multiplex PCR assay that allows the rapid screening of the 19 genes that encode staphylococcal enterotoxins (SEs), SE-like toxins and toxic shock syndrome toxin-1 was also performed and applied in Staph. aureus isolates. The microflora of the skin of patients with AD was dominated by Staph. aureus (69 isolates, 35·6%) followed by Staph. epidermidis (59 isolates, 30·4%) species. The SElM and SElN genes were the most frequently detected in our study (15 isolates, 71·4%), followed by SEG and SElO (14 isolates, 66·7%).

CONCLUSIONS

Our molecular-based approach successfully identified the staphylococcal microflora that was relatively specific to patients with AD. Considering skin colonization and expression of virulence factors, the Staph. aureus may play a relevant role in AD pathophysiology.

SIGNIFICANCE AND IMPACT OF THE STUDY

This ability to classify disease-related microbial species provides new insights into the relevance of those microbes in human disorders.

Repeated intranasal instillation with staphylococcal enterotoxin B induces nasal allergic inflammation in guinea pigs

BACKGROUND

Staphylococcal enterotoxins (SEs) appear to play a role in the pathogenesis of allergic disease. However, no animal models have been reported to show nasal allergic inflammation by repeated inhalation with staphylococcal enterotoxin B (SEB) in the absence of adjuvant. This study was designed to determine whether intranasal instillation of guinea pigs with SEB results in nasal allergic inflammation.

METHODS

Guinea pigs were intranasally instilled with 40 μL of 4-μg SEB once every 4 days 11 times. For the control group, guinea pigs were prepared with saline instead of SEB. Sneezing and nasal scratching frequency were evaluated after each intranasal instillation. The production of antigen-specific antibodies including IgE, nasal eosinophilia, and cytokines in the nasal cavity lavage fluid (NCLF) were measured after the 11th intranasal immunization.

RESULTS

In the model group, symptoms of sneezing and nasal scratching were induced at the 8th to 11th challenges. Intranasal immunization with SEB elicited a local nasal mucosa inflammatory response characterized by apparent eosinophil infiltration. In the NCLF, the expression of IL-4 but not interferon-gamma was increased after challenges. The serum levels of total and SEB-specific IgE and IgG1 were higher in model groups in comparison with the control groups (p < 0.01).

CONCLUSION

These results indicate that repeated intranasal instillation with SEB leads to Th2 immune response, allergic nasal inflammation, and increased antigen-specific IgE production that are characteristic of allergic rhinitis (AR). The model in this study could be valuable in analyzing the pathogenesis of AR infected with Staphylococcus aureus.

Skin-homing CD4+ Foxp3+ T cells exert Th2-like function after staphylococcal superantigen stimulation in atopic dermatitis patients

BACKGROUND

The effect of staphylococcal superantigens (SsAgs) on cutaneous lymphocyte-associated antigen (CLA)(+) CD4(+) Foxp3(+) T cells of atopic dermatitis (AD) patients is unknown.

OBJECTIVE

To compare the effects of SsAgs on the ratio, function, and apoptosis of CCR6(+) subtype and CCR6(-) subtype of CLA(+) CD4(+) Foxp3(+) T cells among AD patients, asthma/allergic rhinitis (AR) patients without AD, and healthy subjects.

METHODS

Using immunofluorescence staining followed by flow cytometric analysis, we analysed peripheral blood mononuclear cells cultured with or without staphylococcal enterotoxin B (SEB) stimulation in 20 AD patients, 20 asthma/AR patients without AD, and 20 healthy subjects.

RESULTS

SEB decreased CCR6(+) /CCR6(-) ratio in CLA(+) CD4(+) Foxp3(+) T cells from AD patients and increased CCR6(+) /CCR6(-) ratio in those from healthy subjects. SEB induced the production of type 2 T helper cell (Th2) cytokine interleukin (IL)-5 in CCR6(-) subtype and anti-inflammatory cytokine IL-10 in CCR6(+) subtype of CLA(+) CD4(+) Foxp3(+) T cells. CLA(+) CD4(+) Foxp3(+) T cells from AD patients produced more IL-5 and less IL-10 after SEB stimulation than those from healthy subjects. CCR6(-) subtype of CLA(+) CD4(+) Foxp3(+) T cells from AD patients and CCR6(+) subtype of those cells from healthy subjects were more resistant to SEB-induced caspase-3 activation than the other subtype and those from other subjects.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite a phenotype of regulatory T cells, skin-homing CD4(+) Foxp3(+) T cells of AD patients exert effector Th2-like function after SsAgs stimulation, which may aggravate allergic skin inflammation.

The role of 9-O-acetylated ganglioside D3 (CD60) and {alpha}4{beta}1 (CD49d) expression in predicting the survival of patients with Sezary syndrome

BACKGROUND

Sézary syndrome is a rare and very aggressive leukemic variant of cutaneous T-cell lymphoma characterized by extensive skin involvement and a malignant circulating CD4(+) T-cell clone which homes to the skin, over-expresses CD60, and lacks CD7, CD26 and CD49d. So far prognostic markers in this disease are limited to treatment with systemic steroids, age, serum lactate dehydrogenase, and a white blood cell count of 20×10(9)/L or higher: no other biological marker with prognostic value, especially related to malignant cells, has been described.

DESIGN AND METHODS

We used flow activated cell sorting analysis to compare the distribution of the T-cell receptor-Vβ repertoire and several surface molecules (CD7, CD26, CD49d and CD60) within the circulating CD4(+) T-cell population in 62 patients with Sézary syndrome, 180 with mycosis fungoides, 6 with B-cell lymphomas, and 19 with chronic eczema. We calculated the 5-year overall survival of patients with Sézary syndrome after first hospital admission using Kaplan-Meier product-limit estimates and hazard ratios from the Cox proportional hazards model.

RESULTS

We found that both higher number of CD60(+) and lower number of CD49d(+) cells within circulating CD4(+) T cells at disease presentation were significantly associated with a lower probability of survival. An exceedingly high risk of death was observed for patients with a combination of a high proportion of CD4(+)CD60(+) cells (≥ 0.5×10(9)/L) and low proportion of CD4(+)CD49d(+) cells (<0.5×10(9)/L) (hazard ratio = 12.303, 95% confidence interval 1.5-95.9; P<0.02). In addition, a skewed usage of T-cell receptor-Vβ subfamilies was observed in the circulating T-cell clone for 61.9% of all patients with Sézary syndrome, T-cell receptor-Vβ 2 and 5.1 subfamilies being the most frequently represented (42.8%), followed by T-cell receptor-Vβ 12 and 13.1.

CONCLUSIONS

In this study we showed that up-regulation of CD60 and down-regulation of CD49d on circulating CD4(+) T cells are two useful markers for predicting a very poor outcome in patients with Sézary syndrome.

Role of bacterial pathogens in atopic dermatitis

The skin of atopic dermatitis (AD) patients exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. This review summarizes our understanding about the role of S. aureus in AD. Indeed, S. aureus colonization is both a cause and a consequence of allergic skin inflammation. The mechanisms that allergic skin inflammation of AD promotes the increase of S. aureus colonization include skin barrier dysfunction, increased synthesis of the extracellular matrix adhesins for S. aureus, and defective innate immune responses due to decreased production of endogenous antimicrobial peptides. On the other hand, the exotoxins secreted by S. aureus are superantigens. Staphylococcal superantigens (SsAgs) may penetrate the skin barrier and contribute to the persistence and exacerbation of allergic skin inflammation in AD through the stimulation of massive T cells, the role of allergens, direct stimulation of antigen-presenting cells and keratinocytes, the expansion of skin-homing cutaneous lymphocyte-associated antigen-positive T cells, and the augmentation of allergen-induced skin inflammation. SsAgs also induce corticosteroid resistance. In therapeutic interventions, anti-inflammatory therapy alone is very effective in reducing S. aureus colonization on the skin, but antibiotic treatment alone is unable to improve the allergic skin inflammation of AD. Therefore, we recommend the combination therapy of anti-inflammatory drugs and antibiotics in the AD patients with secondary bacterial infection, exacerbated AD, or poorly controlled AD. However, when AD is well controlled by anti-inflammatory drugs alone, we do not recommend the antibiotic therapy.

Staphylococcus aureus sensitization and allergic disease in early childhood: Population-based birth cohort study

BACKGROUND

Staphylococcus aureus-secreted enterotoxins (SEs) may be involved in the pathophysiology of atopic diseases.

OBJECTIVE

We investigated the role of SEs in allergic diseases during early childhood (using the mixture of SE-specific IgEs [SE-mix] as a marker).

METHODS

Children (N = 510) were followed from birth to age 5 years (repeated questionnaires, IgE to inhalant and food allergens, lung function [spirometry, plethysmography], airway reactivity [dry air challenge]). We measured SE-mix specific IgE (SE-A, SE-C, toxic shock syndrome toxin 1) by using fluorescence immunoassay.

RESULTS

We found no association between rhinitis and SE-mix sensitization. Children with eczema were more frequently SE-mix-sensitized than children without (17.4% vs 8.3%; P = .02). SE-mix sensitization rate increased significantly with increasing eczema severity (no eczema, mild, moderate/severe: 8.3%, 14.8%, 42.9%; P = .003) and remained independently associated with eczema in a multivariate model adjusting for total IgE (adjusted odds ratio, 2.19; 95% CI, 1.05-4.56; P = .04). SE-mix sensitization was associated with current wheeze in the univariate but not the multivariate model. Among wheeze phenotypes, persistent wheezers were most commonly sensitized to SE-mix (never, transient, late-onset, persistent: 8.5%, 3.8%, 7.7%, 17.6%; P = .05). Among wheezers, those SE-mix-sensitized had significantly higher airway reactivity compared with those nonsensitized (mean FEV(1) change, mL [95% CI]: -59 [-121, 3] vs 19 [-10.2, 48.9]; P = .04), with little difference after adjusting for atopy.

CONCLUSION

We found differences in SE-mix IgE antibodies between healthy 5-year-old children and children with eczema and wheeze. The proportion of patients sensitized to SE-mix increases with increasing disease severity.

CLINICAL IMPLICATIONS

Staphylococcal enterotoxins are potential modifiers of childhood wheeze and eczema.

The importance of bacterial superantigens produced by Staphylococcus aureus in the treatment of atopic dermatitis using povidone-iodine

Atopic dermatitis (AD) is frequently associated with intestinal and cervical lesions. Staphylococcus aureus produces many kinds of toxins, the bacterial superantigens. The detection rate of toxins was 80.1% from 196 S. aureus strains. Neurological examinations revealed abnormalities in 59 out of 81 AD patients. Cervical magnetic resonance imaging (MRI) was performed in 46 patients randomly and showed abnormal findings in 38 of these patients. In 23 patients who underwent MRI and duodenal biopsy, 3 were found to be normal neurologically and 2 patients showed normal duodenal tissue. However, 18 patients had abnormal findings both on neurological examination and in duodenal tissue. Serial duodenal biopsy tests were performed in 10 AD patients. In 5 patients, the findings of chronic duodenitis disappeared after the therapy with povidone-iodine. These data indicate that the therapy was effective not only for the skin lesions, but improved gastrointestinal tract lesions and cervical myelopathy, by eradicating bacterial superantigens.

Genotypic characterization of toxic shock syndrome toxin-1-producing strains of Staphylococcus aureus isolated in the Czech Republic

Genotyping based on pulsed-field gel electrophoresis (PFGE), PCR ribotyping, enterobacterial repetitive intergenic consensus motif (ERIC2)-PCR, and prophage content analysis was carried out in 45 toxic shock syndrome toxin-1 (TSST-1)-positive Staphylococcus aureus strains isolated in 19 cities of the Czech Republic between 1986 and 2004. Twenty-four wild-type TSST-1-positive isolates of which 18 strains were the causative agents of toxic shock syndrome (TSS) had the same genotype profiles as the type strain FRI 1169 and were classified into genotype T1. The remaining 21 strains of which 12 caused TSS were distinct from one another and differed from the T1 strains mainly in PFGE pattern and also in one or more other genetic characteristics. While the strains of genotype T1 are most prevalent in the Czech population and account for the majority of TSS cases, TSS-related S. aureus strains of different genotypes were also found and cannot be excluded as the causative agents of TSS cases in this country.

Evidence for Restricted Vβ Usage in the Leukemic Phase of Cutaneous T Cell Lymphoma

Antibodies directed against the beta chain of the T cell receptor (anti-Vbeta antibodies) are useful to identify the Vbeta repertoire of T cells in various diseases and to quantify numbers of Vbeta-bearing T cells. The goals of this study were to identify Vbeta+ cases of leukemic phase cutaneous T cell lymphoma (CTCL) and to compare the percentage of positive calls with other measures of blood tumor burden, i.e., lymphocyte subsets with a CD4+CD7- and CD4+CD26- phenotype and Sezary cell counts. Thirty-three of 49 (67%) cases of leukemic CTCL reacted with an anti-Vbeta antibody. When combined with reports from the literature, the frequency of Vbeta5 (probably Vbeta5.1) usage was relatively high when compared with Vbeta2 that is also frequently expressed by normal CD4+ T cells. The percentage of Vbeta+ cells correlated to the percentage of CD4+CD7- and CD4+CD26- cells for cases in which the neoplastic cells were deficient in expression of CD7 and CD26, respectively, but not the Sezary cell count. We hypothesize that the increased Vbeta5.1 usage in CTCL may be the result of depletion of Vbeta2 and other Vbeta-bearing T cells by staphylococcal superantigens prior to neoplastic transformation, resulting in a relative increase in the frequency of Vbeta5.1 usage in CTCL.

Immunoglobulin E to staphylococcal and streptococcal toxins in patients with chronic sinusitis/nasal polyposis

BACKGROUND

The role of infectious agents and their contribution to the inflammation in chronic sinusitis/nasal polyposis (CS/NP) is not clear. Staphylococcal and streptococcal toxins have superantigen activity and have been implicated in inflammatory conditions such as atopic dermatitis, psoriasis, and asthma.

OBJECTIVE

We investigated the presence of immunoglobulin (Ig)E antibodies to staphylococcal and streptococcal toxins in the serum of individuals with CS/NP.

METHOD

IgE antibodies to staphylococcal exotoxins, A, B, and toxic shock syndrome toxin-1 and streptococcal pyrogenic exotoxin A, B, and C were measured in 23 individuals with CS/NP before functional endoscopic sinus surgery and in controls (7 atopic and 6 nonatopic) individuals without chronic sinusitis. Presence of IgE to the toxins was also correlated with disease severity on sinus computed tomography (CT) scans.

RESULTS

Staphylococcal and streptococcal toxin specific IgE antibodies were detected in 18 of 23 (78%) and 7 of 21 (33.3%) patients, respectively. None of the controls had IgE to the staphylococcal or streptococcal toxins (P <.0001). There was no association between radiographic severity of sinus disease and the presence of IgE antibody to the toxins.

CONCLUSION

A significantly greater proportion of CS/NP patients had IgE to staphylococcal or streptococcal toxins. Evidence of IgE antibodies directed against staphylococcal and streptococcal toxins in the sera of patients with CS/NP suggests a potential role of these toxins with established superantigen effects in the pathogenesis of CS/NP.

Secondary infections in patients with atopic dermatitis

Clinicians have long since been aware that bacteria and other microorganisms play a role in the etiology of atopic dermatitis. Indeed, the immunological profile of atopy favors colonization by Staphylococcus aureus, and the bacteria are present in most patients with atopic dermatitis, even in the absence of skin lesions. Clinical signs of impetiginization, such as weeping and crusting, periauricular fissuration, or small superficial pustules are a sensitive indicator that the numbers of S. aureus may have increased and a clinical indication of secondary infected dermatitis. However, recent research that has focussed on the role of S. aureus in atopic dermatitis, offers a reversed perspective, by presenting evidence that the underlying pathology of atopic dermatitis, i.e. an alteration of the skin barrier and inflammation of the upper dermis, depends itself on the presence of an infectious process. In other words, secondary infection with S. aureus emerges as a cause of atopic dermatitis. Secondary infections due to fungi have, comparatively, received less attention, but there is evidence for a role for Malassezia spp. as a factor in dermatitis with a head and neck distribution pattern. Viral infections, such as herpes simplex virus, and mixed infections of intertriginous spaces, may complicate an underlying atopic dermatitis, but are not perceived as etiologic factors. Recent research has greatly contributed to our understanding of the pathophysiological potential of S.aureus superantigens in atopic dermatitis, suggesting that antibiotic therapy might be an important element in the therapeutic management of atopic dermatitis. At present, however, the clinical evidence is scarce with regards to demonstrating a clear advantage of combined anti-inflammatory and antibiotic treatment, compared with anti-inflammatory treatment alone. If there is a consensus that the presence of clinically infected lesions in atopic dermatitis warrants a course of specific antibiotic topical therapy, the clinical benefit of antibiotic agents in apparently uninfected atopic dermatitis, as present in the majority of patients, remains an open question.Moreover, the impact of adjuvant skin care on the cutaneous microflora needs to be quantified in order to properly assess the role of specific antibiotic therapy in clinically uninfected atopic dermatitis. In the meantime, secondary infections in atopic dermatitis remain a secondary problem in clinical atopic dermatitis management, and specific anti-infective therapy remains a method of fine-tuning for optimizing individual atopic dermatitis treatment.

Staphylococcal exotoxins exert proinflammatory effects through inhibition of eosinophil apoptosis, increased surface antigen expression (CD11b, CD45, CD54, and CD69), and enhanced cytokine-activated oxidative burst, thereby triggering allergic inflammatory reactions

BACKGROUND

Staphylococcus aureus colonization of the skin represents a potent trigger factor of atopic dermatitis. Our previous studies demonstrated that in atopic dermatitis eosinophil apoptosis is significantly delayed.

OBJECTIVE

We sought to investigate the effect of staphylococcal exotoxins (SETs) on eosinophil apoptosis and functional activities.

METHODS

Apoptotic eosinophils were investigated by determining their hypodiploid DNA peak. Eosinophil surface-antigen expression and intracellular production of hydrogen peroxide were assessed by means of flow cytometric analysis and respiratory burst by lucigenin-dependent chemiluminescence.

RESULTS

The SETs SEA, SEB, SEC, and toxic shock syndrome toxin 1 significantly inhibited eosinophil apoptosis in a manner comparable with that of high concentrations of IL-3. The LPS inhibitor polymyxin B was found to significantly inhibit LPS-mediated, but not SET-mediated, inhibition of apoptosis. Neither SETs nor LPS was able to modulate eosinophil surface expression of CD9, CD11a, CD16, CD40, CD44, or CD63. However, 24- and 48-hour incubation with all SETs, but not with LPS, significantly upregulated expression of CD11b and CD45 in a manner similar to that of IL-3, whereas dexamethasone induced a downregulation. Moreover, all SETs resulted in a significant upregulation of CD54 after 24 hours but not after 48 hours. Interestingly, CD69 was upregulated by means of IL-3 and SEB only. Neither direct stimulation of eosinophils nor 24-hour incubation with SETs or stimulation with SETs after a 24-hour prestimulation with IL-3, IL-5, or GM-CSF resulted in a significant extracellular production of reactive oxygen species or in a significant production of intracellular hydrogen peroxide. However, SEB and toxic shock syndrome toxin 1 were able to enhance cytokine-induced respiratory burst.

CONCLUSION

Taken together, our data demonstrate that SETs may modulate the course of the allergic inflammatory response through modulation of potent eosinophil effector functions. This may be of particular importance in atopic dermatitis, in which the skin is regularly colonized with SET-producing S aureus.

Comparative study of Staphylococcus aureus isolated from lesional and non-lesional skin of atopic dermatitis patients

The skin of patients with atopic dermatitis (AD) is often colonized by Staphylococcus aureus, and superantigenic exotoxins produced by the organism are thought to be an important precipitating factor of AD. However, there are few reports comparing the characteristics of S. aureus isolated from the lesional and non-lesional skin of identical AD patients. In this study, therefore, we examined whether the presence of superantigen-producing S. aureus correlates with the formation of eczematous lesion of AD patients. The detection rate of S. aureus on the lesional skin of AD patients was higher than on the non-lesional skin of AD patients. Furthermore, the bacterial cell count of S. aureus on the lesional skin of AD patients was also significantly higher than that of the non-lesional skin of AD patients. However, there was no significant difference between the detection rate of superantigenic exotoxin-producing S. aureus on the lesional and nonlesional skin of AD patients. These results suggest that the number of S. aureus present is more important in the formation of eczematous lesion of AD patients than the presence of superantigenic exotoxin-producing S. aureus strains per se.

The production of superantigenic exotoxins by coagulase-negative staphylococci isolated from human skin lesions

We examined the production of superantigenic exotoxins in 136 coagulase-negative staphylococci isolated from various skin lesions in humans using a reversed passive latex agglutination test (Denka Seiken). As a control we examined the same in 50 Staphylococcus aureus strains isolated from non-infective skin ulcers in humans. Of the 136 strains of coagulase negative-staphylococci, 9 (6.6%) produced one or more identifiable exotoxins. In contrast, 21 (42%) out of the 50 S. aureus strains produced one or more identifiable exotoxins (P<0.01).

Colonization with superantigen-producing Staphylococcus aureus is associated with increased severity of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with colonization of the skin with Staphylococcus aureus known to produce toxins with superantigen (SAg) activity. Besides T-cell activation these toxins induce T-cell skin homing in vitro. This may contribute to the observed induction or enhancement of skin inflammation.

OBJECTIVE

The aim of this study was to determine whether colonization with SAg-producing S. aureus isolates modulates the intensity of AD. If so, it was of interest whether this may be primarily due to the toxins' effects as SAgs or as allergens.

METHODS

In AD patients, healthy controls, and atopic controls SAg production by S. aureus isolated from skin or mucous membranes was investigated and correlated to the severity of the disease. Total IgE, SAg-specific IgE, and T-cell activation and recirculation markers were analysed and correlated with SAg production.

RESULTS

Fifty-seven percent of S. aureus strains isolated from AD patients produced SAgs. This frequency was higher compared to healthy controls (33%). SAg production by S. aureus was correlated with a significantly higher scoring of AD (SCORAD index, 58 +/- 19 in SAg-producing vs 41 +/- 7 in non-SAg-producing germs; P < 0.05). However, the severity of the disease was not associated with sensitization against the SAgs staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin B (SEB). Furthermore, SAg production by S. aureus was inversely correlated with total IgE concentration (P < 0.05) and positively correlated with T-cell activation (as measured by HLA-DR and CD69 expression) and the expression of the T-cell skin homing phenotype cutaneous lymphocyte-associated antigen.

CONCLUSION

SAg production by S. aureus is suggested to be associated with an increased severity of atopic dermatitis. Since SAg production was found neither exclusively in AD patients nor in all patients, other pathogenic factors may be additionally effective.

Comparison of serum specific IgE antibodies to staphylococcal enterotoxins between atopic children with and without atopic dermatitis

BACKGROUND

The skin of patients with atopic dermatitis (AD) exhibits a striking susceptibility to colonization and infection by Staphylococcus aureus. The exotoxins secreted by S. aureus can act as superantigens and classic allergens, inducing the production of functionally relevant specific IgE antibodies. The aim of this study was to compare the levels and positive rates of serum staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE between atopic children with and without AD.

METHODS

Sixty children with AD, 55 children with respiratory allergy without AD, and 24 nonatopic healthy children were studied. The levels and positive rates of serum SEA- and SEB-specific IgE were compared among three groups. The correlation between the levels or positive rates of serum SEA/SEB-specific IgE and the severity of AD or the presence of previous skin infections was studied.

RESULTS

The children with AD had significantly higher levels and positive rates of serum SEA- and SEB-specific IgE than the atopic children without AD (P < 0.001) and the nonatopic children (P < 0.001). There was no significant difference in the levels and positive rates of serum SEA- and SEB-specific IgE between the atopic children without AD and the nonatopic children. With or without adjustment for the potential confounding effect of total serum IgE levels, the levels and positive rates of serum SEA- and SEB-specific IgE were significantly correlated with severity of AD (P <0.005), but they were not significantly different between AD children with and without previous skin infections.

CONCLUSIONS

SEA and SEB may contribute to chronic inflammation and exacerbation of AD through the IgE-mediated immune response.

Severe atopic dermatitis is associated with sensitization to staphylococcal enterotoxin B (SEB)

BACKGROUND

Staphylococcus aureus has been identified as a possible trigger factor in atopic dermatitis (AD). Some 30-60% of S. aureus strains isolated from patients with AD are able to produce exotoxins with superantigenic properties, mostly staphylococcal enterotoxins A, B, C, and D (SEA-D) and toxic shock syndrome toxin-1 (TSST-1). Recently, it was demonstrated that the presence of IgE antibodies to SEA and SEB is correlated with the severity of skin lesions in children with AD. To determine the relevance of staphylococcal enterotoxins in adult patients with AD, we investigated the relationship between the severity of skin lesions and sensitization to SEA and SEB.

METHODS

Clinical severity was determined by the SCORAD index. Circulating IgE antibodies to SEA and SEB, serum eosinophil cationic protein (ECP) levels, and urine eosinophil protein X (EPX) levels were measured.

RESULTS

The skin condition was significantly worse in patients sensitized to SEB than in unsensitized patients. Serum ECP and urine EPX levels were found to be significantly higher in SEB-sensitized patients, confirming the higher degree of cutaneous inflammation.

CONCLUSIONS

Our results demonstrate a relationship between severity of skin lesions and sensitization to SEB in adult patients with AD, but a relationship between disease activity and sensitization to SEA could not be shown.

Possible influences of Staphylococcus aureus on atopic dermatitis-- the colonizing features and the effects of staphylococcal enterotoxins

BACKGROUND

Heavy colonization of atopic dermatitis (AD) with Staphylococcus aureus is well documented. This phenomenon suggests that S. aureus in AD lesions influences the disease processes of AD.

OBJECTIVE

We describe the importance of the presence of S. aureus and staphylococcal enterotoxins A and B (SEA, SEB) in AD lesions.

METHODS

We investigated the colonizing features of S. aureus in AD lesions using electron microscopy, the distribution of SEB in the eczematous skin of AD using immunofluorescence, the effects of SEA and SEB on normal human epidermal keratinocytes in organ culture, and the presence of specific IgE antibodies to SEA and/or SEB in serum of AD patients by enzyme immunoassay.

RESULTS

S. aureus in AD lesions colonized on and in the horny layers of the eczematous skin. SEB produced by S. aureus was distributed mainly on the dermal-infiltrated cells, especially on eosinophils. SEA and SEB stimulated expression of ICAM-1 and HLA-DR in normal human keratinocytes. More than half of the AD patients in the present study had specific IgE antibodies to SEA and/or SEB in their serum.

CONCLUSION

S. aureus and SEs have important roles in the exacerbation and prolongation of AD.

Prevalence and role of serum IgE antibodies to the Staphylococcus aureus-derived superantigens SEA and SEB in children with atopic dermatitis

BACKGROUND

The skin of patients with atopic dermatitis exhibits a striking susceptibility to colonization and infection with Staphylococcus aureus. In this context it has been previously shown that S aureus-derived superantigens could function as classic allergens, inducing production of functionally relevant specific IgE antibodies.

OBJECTIVE

The aim of this study was to determine the prevalence and the role of circulating staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE antibodies in children with atopic dermatitis.

METHODS

In a cross-sectional study of 58 children with atopic dermatitis, the presence of IgE antibodies to SEA and SEB was correlated with the severity of the disease and the total and other unrelated allergen-specific IgE titers and density of colonization with S aureus strains on atopic skin and episodes of superficial S aureus skin infections.

RESULTS

Twenty of 58 children (34%) were sensitized to superantigens (45% to SEB, 10% to SEA, 45% to SEA and SEB). In this group, severity of atopic dermatitis and levels of specific IgE to food and air allergens were significantly higher. The degree of disease severity correlated to a higher extent with the presence of SEA/SEB-specific antibodies than with total serum IgE levels. Density of colonization with superantigen-secreting S aureus strains was higher in the superantigen IgE-positive group. Sixty-three percent of these children experienced repeated episodes of superficialS aureus skin infections.

CONCLUSIONS

Sensitization to S aureus-derived superantigens may be involved in disease exacerbation. The presence of SEA/SEB-specific antibodies had additional explanatory value for disease severity and therefore may be helpful in the characterization of children with severe atopic dermatitis.

Effects of zinc oxide on the attachment of Staphylococcus aureus strains

We examined the attachment of Staphylococcus aureus to plastic tissue-culture coverslips after incubation for 24 h. The attachment to coverslips was weaker in rabbit plasma with 5% zinc oxide (ZnO) than in the control rabbit plasma without ZnO (P < 0.01). Plasma coagulation by S. aureus strains was not detected in plasma with 5% ZnO after incubation for 24 h. The membranous structure (an immature biofilm) was formed on the coverslips by S. aureus cells in plasma after incubation for 24 h. The colony counts of S. aureus cells on the membranous structures were lower in plasma with 5% ZnO, plasma with 0.2% hinokitiol, plasma with 5% ZnO + 0.2% hinokitiol, plasma with cefdinir at 4 minimum inhibitory concentration (MIC) and plasma with levofloxacin at 4 MIC, than in the control plasma after incubation for 24 h (P < 0.01). The colonies on the membranous structures completely disappeared in the case of plasma with 5% ZnO and 0.2% hinokitiol. The colony counts on membranous structures were lower in plasma with cefdinir at 4 MIC or levofloxacin at 4 MIC containing 5% ZnO than in plasma with cefdinir at 4 MIC or levofloxacin at 4 MIC only, (P < 0.05). The MICs of hinokitiol against S. aureus strains peaked at an MIC distribution of 16-32 micrograms/ml. The peak shifted to below 1 microgram/ml by adding 5% ZnO in agar plate method. The results suggest that the attachment of S. aureus cells to the coverslips is suppressed in the presence of 5% ZnO and that antistaphylococcal activities of cefdinir, levofloxacin and hinokitiol increase in the presence of 5% ZnO.

Effects of various salts and irradiation with UV light on the attachment of Staphylococcus aureus strains

We investigated the attachment of Staphylococcus aureus isolated from atopic dermatitis lesions to plastic tissue-culture coverslips. We found that attachment was weaker in (rabbit) plasma with 5 or 10% NaCl and in plasma with 5 or 10% sea salts than in the control plasma after incubation for 2 h (P < 0.01). The attachment was weaker still in plasma with 10% NaCl or 10% sea salts than in the control plasma after incubation for 24 h (P < 0.01). Plasma coagulation of four S. aureus strains isolated from atopic dermatitis lesions was not detected in plasma with 10% NaCl (pH 5.6) or 10% sea salts (containing 0.372% Mg2+) after incubation for 12, 24, 36 and 60 h. The attachment of S. aureus strain cells to the coverslip in plasma was weaker after irradiation with UVA at 25 or 50 J/cm2 (P < 0.01) and UVB at 0.5 J/cm2 (P < 0.05) both of which are covered by a black cloth, than without irradiation after incubation for 24 h. Plasma coagulation was not detected after irradiation with UVA at 25 or 50 J/cm2 with a black cloth cover (temperature reached 50 degrees C), but was detected after UVA irradiation at the same doses combined with cooling (temperature reached 22 degrees C), after incubation for 24 h. The results suggest that the attachment of S. aureus cells isolated from atopic dermatitis lesions to the coverslip is suppressed in the presence of 10% salts and irradiation with UVA and UVB, and that plasma coagulation of S. aureus cells isolated from atopic dermatitis lesions is suppressed in the presence of 10% salts, irradiation with UVA, and heating.

Changes in Staphylococcus aureus density and lesion severity after topical application of povidone-iodine in cases of atopic dermatitis

A case-control study was performed to examine the efficacy of 10% povidone-iodine solution applied to atopic dermatitis patients. The density of Staphylococcus aureus on the eczematous lesions and the lesion severity before and after the topical application of povidone-iodine were compared. We found a 10-100-fold decrease in the density of S. aureus after povidone-iodine treatment in patients colonizing S. aureus at an initial density of > 1000 CFU/10 cm2. Erythema and exudation also decreased after povidone-iodine treatment in patients colonizing S. aureus at an initial density of > 1000 CFU/10 cm2. The 10% povidone-iodine solution disinfected S. aureus cells when added immediately after the cells were mixed in human plasma; however, 10% povidone-iodine solution only reduced the density of S. aureus cells by 10-100-fold when S. aureus cells were harvested after a 24 h incubation in human plasma. Staphylococcus aureus cells harvested after 24 h incubation in human plasma were often surrounded by fibrin bundles and cells circumscribed by fibrin bundles could not be disinfected with 10% povidone-iodine solution. We suggest that S. aureus cells may produce biofilm-like structures in atopic dermatitis patients and that these structures may help S. aureus cells resist the 10% povidone-iodine treatment.