Are there predominant strains and toxins ofStaphylococcus aureusin atopic dermatitis patients? Genotypic characterization and toxin determination ofS. aureusisolated in adolescent and adult patients with atopic dermatitis

Distinct prophage gene profiles of Staphylococcus aureus strains from atopic dermatitis patients and healthy individuals

Staphylococcus aureus strains exhibit varying associations with atopic dermatitis (AD), but the genetic determinants underpinning the pathogenicity are yet to be fully characterized. To reveal the genetic differences between S. aureus strains from AD patients and healthy individuals (HE), we developed and employed a random forest classifier to identify potential marker genes responsible for their phenotypic variations. The classifier was able to effectively distinguish strains from AD and HE. We also uncovered strong links between certain marker genes and phage functionalities, with phage holin emerging as the most pivotal differentiating factor. Further examination of S. aureus gene content highlighted the genetic diversity and functional implications of prophages in driving differentiation between strains from AD and HE. The HE group exhibited greater gene content diversity, largely influenced by their prophages. While strains from both AD and HE universally housed prophages, those in the HE group were distinctively higher at the strain level. Moreover, although prophages in the HE group exhibited variously higher enrichment of differential functions, the AD group displayed a notable enrichment of virulence factors within their prophages, underscoring the important contribution of prophages to the pathogenesis of AD-associated strains. Overall, prophages significantly shape the genetic and functional profiles of S. aureus strains, shedding light on their pathogenic potential and elucidating the mechanisms behind the phenotypic variations in AD and HE environments.

IMPORTANCE

Through a nuanced exploration of Staphylococcus aureus strains obtained from atopic dermatitis (AD) patients and healthy controls (HE), our research unveils pivotal genetic determinants influencing their pathogenic associations. Utilizing a random forest classifier, we illuminate distinct marker genes, with phage holin emerging as a critical differential factor, revealing the profound impact of prophages on genetic and pathogenic profiles. HE strains exhibited a diverse gene content, notably shaped by unique, heightened prophages. Conversely, AD strains emphasized a pronounced enrichment of virulence factors within prophages, signifying their key role in AD pathogenesis. This work crucially highlights prophages as central architects of the genetic and functional attributes of S. aureus strains, providing vital insights into pathogenic mechanisms and phenotypic variations, thereby paving the way for targeted AD therapeutic approaches and management strategies by demystifying specific genetic and pathogenic mechanisms.

Staphylococcus aureus Adaptation to the Skin in Health and Persistent/Recurrent Infections

Staphylococcus aureus is a microorganism with an incredible capability to adapt to different niches within the human body. Approximately between 20 and 30% of the population is permanently but asymptomatically colonized with S. aureus in the nose, and another 30% may carry S. aureus intermittently. It has been established that nasal colonization is a risk factor for infection in other body sites, including mild to severe skin and soft tissue infections. The skin has distinct features that make it a hostile niche for many bacteria, therefore acting as a strong barrier against invading microorganisms. Healthy skin is desiccated; it has a low pH at the surface; the upper layer is constantly shed to remove attached bacteria; and several host antimicrobial peptides are produced. However, S. aureus is able to overcome these defenses and colonize this microenvironment. Moreover, this bacterium can very efficiently adapt to the stressors present in the skin under pathological conditions, as it occurs in patients with atopic dermatitis or suffering chronic wounds associated with diabetes. The focus of this manuscript is to revise the current knowledge concerning how S. aureus adapts to such diverse skin conditions causing persistent and recurrent infections.

Comprehensive Genomic Characterization of Staphylococcus aureus Isolated from Atopic Dermatitis Patients in Japan: Correlations with Disease Severity, Eruption Type, and Anatomical Site

Atopic dermatitis (AD) shows frequent recurrence. Staphylococcus aureus is the primary microbial component in AD and is associated with disease activity. However, traditional typing methods have failed to characterize virulent AD isolates at the clone level. We conducted a comprehensive genomic characterization of S. aureus strains isolated from the skin of AD patients and healthy donors, comparing the whole-genome sequences of the 261 isolates with anatomical and lesional (AD-A)/nonlesional (AD-NL)/healthy sites, eruption types, clinical scores, virulence, and antimicrobial resistance gene repertoires in Japan. Sequence type (ST) diversity was lost with worsening disease activity; ST188 was the most frequently detected ST in AD-A and had the strongest correlation with AD according to the culture rate and proportion with worsening disease activity. ST188 and ST20 isolates inhabited all skin conditions, with significantly higher proportions in AD skin than in healthy skin. ST8, ST15, and ST5 proportions were equivalent for all skin conditions; ST30 was detected only in healthy skin; and ST12 was detected only in AD skin. ST97 detected in AD-A and healthy skin was clearly branched into two subclades, designated ST97A and ST97H. A comparison of two genomes led to the discovery that only ST97A possessed the complete trp operon, enabling bacterial survival without exogenous tryptophan (Trp) on AD skin, where the Trp level was significantly reduced. Primary STs showing an AD skin inhabitation trend (ST188, ST97A, ST20, and ST12) were all trp operon positive. The predominant clones (ST188 and ST97) possessed almost no enterotoxin genes, no mecA gene, and few other antimicrobial resistance genes, different from the trend observed in Europe/North America. IMPORTANCE While Staphylococcus aureus is a member of the normal human skin flora, its strong association with the onset of atopic dermatitis (AD) has been suggested. However, previous studies failed to assign specific clones relevant to disease activities. Enterotoxins produced by S. aureus have been suggested to aggravate and exacerbate the inflammation of AD skin, but their role remains ambiguous. We conducted a nuanced comprehensive characterization of isolates from AD patients and healthy donors, comparing the whole-genome sequences of the isolates with anatomical and lesional/nonlesional/healthy sites, eruption types, clinical scores, virulence, and antimicrobial resistance gene repertoires in Japan. We demonstrate that specific clones are associated with disease severity and clinical manifestations, and the dominant clones are devoid of enterotoxin genes and antimicrobial resistance genes. These findings undermine the established notion of the pathophysiological function of S. aureus associated with AD and introduce a new concept of S. aureus colonization in AD.

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.

Methicillin-resistant and methicillin-sensitive Staphylococcus aureus isolates from skin and nares of Brazilian children with atopic dermatitis demonstrate high level of clonal diversity

BACKGROUND

Atopic dermatitis (AD) primarily affects the pediatric population, which is highly colonized by S. aureus. However, little is known about the genetic features of this microorganism and other staphylococcal species that colonize AD patients.

OBJECTIVE

This study aimed to characterize Staphylococcus spp. isolated from the nares and skin (with and without lesion) of 30 AD and 12 non-AD Brazilian children.

METHODS

Skin and nasal swabs were cultured onto mannitol salt agar, and bacterial colonies were counted and identified by matrix assisted laser desorption ionization time of flight mass spectrometry and polymerase chain reaction (PCR). Antimicrobial susceptibility was evaluated by phenotypic and genotypic tests. In S. aureus isolates, Panton-Valentine leukocidin genes were detected by PCR, and their clonality was assessed by pulsed-field gel electrophoresis and multilocus sequence typing.

RESULTS

S. aureus was more prevalent in the nares (P = 0.005) and lesional skin (P = 0.0002) of children with AD, while S. hominis was more frequent in the skin of non-AD children (P < 0.0001). All children in the study, except one from each group, were colonized by methicillin-resistant coagulase-negative Staphylococcus and 24% by methicillin-resistant S. aureus. Despite the great clonal diversity of S. aureus (18 sequence types identified), most AD children (74.1%) were colonized by the same genotype in both niches.

CONCLUSION

High colonization by polyclonal S. aureus isolates was found among children with AD, while S. hominis was more frequent among non-AD children. The high prevalence of methicillin-resistant staphylococcal isolates highlights the importance of continued surveillance, especially when considering empiric antibiotic therapy for the treatment of skin infections in these patients.

A review of the mechanisms of keratinocytes damage caused by Staphylococcus aureus infection in patients with atopic dermatitis

The dysregulation of skin microflora in patients with atopic dermatitis (AD) has become a research hotspot in recent years. Metagenomic studies have shown that microbial diversity is decreased, whereas the Staphylococcus aureus infection is increased in AD. Keratinocytes are the primary barrier against the invasion of external pathogenic microorganisms. Staphylococcus aureus infection can abnormally activate innate and adaptive immune responses in keratinocytes, resulting in a vicious cycle between Staphylococcus aureus infection and AD. This article reviews the mechanisms of inflammatory damage of keratinocytes induced by Staphylococcus aureus infection in patients with AD, providing a theoretical basis for the study of new targeted drugs. This review also suggests for the management of Staphylococcus aureus infection in patients with AD.

Hand eczema and temporal variation of Staphylococcus aureus clonal complexes: A prospective observational study

BACKGROUND

Hand eczema (HE) is frequently associated with Staphylococcus aureus; however, its role in the pathogenesis of HE is poorly understood.

OBJECTIVE

To investigate the temporal variation in S aureus subtypes, ie, clonal complex (CC) types, on the hands and relate it to S aureus colonization in the nose and severity in a cohort of HE patients.

METHODS

S aureus from the hands and nose of 50 adult HE patients and 50 controls was prospectively identified at 5 visits over 3 weeks.

RESULTS

S aureus was identified on the hands of 23 (46%) patients at 2 or more visits and on the hands of 1 control once. Of the HE patients with S aureus colonization, 78% had the same S aureus CC type over time. Twenty-one patients had the same S aureus CC type on the hands and in the nose. Persistent colonization was strongly related to an increased disease severity.

LIMITATIONS

A relatively small S aureus culture-positive population.

CONCLUSION

The temporal stability of S aureus CC type and high occurrence of the identical subtypes on the hands and in the nose imply that S aureus colonization in patients with HE is of a more permanent nature. Taken together with the finding that persistent colonization and HE severity are clearly related, our results indicate that S aureus may contribute to the perpetuating course of HE.

Molecular epidemiology of Staphylococcus aureus in African children from rural and urban communities with atopic dermatitis

Background

Staphylococcus aureus has been associated with the exacerbation and severity of atopic dermatitis (AD). Studies have not investigated the colonisation dynamics of S. aureus lineages in African toddlers with AD. We determined the prevalence and population structure of S. aureus in toddlers with and without AD from rural and urban South African settings.

Methods

We conducted a study of AD-affected and non-atopic AmaXhosa toddlers from rural Umtata and urban Cape Town, South Africa. S. aureus was screened from skin and nasal specimens using established microbiological methods and clonal lineages were determined by spa typing. Logistic regression analyses were employed to assess risk factors associated with S. aureus colonisation.

Results

S. aureus colonisation was higher in cases compared to controls independent of geographic location (54% vs. 13%, p < 0.001 and 70% vs. 35%, p = 0.005 in Umtata [rural] and Cape Town [urban], respectively). Severe AD was associated with higher colonisation compared with moderate AD (86% vs. 52%, p = 0.015) among urban cases. Having AD was associated with colonisation in both rural (odds ratio [OR] 7.54, 95% CI 2.92–19.47) and urban (OR 4.2, 95% CI 1.57–11.2) toddlers. In rural toddlers, living in an electrified house that uses gas (OR 4.08, 95% CI 1.59–10.44) or utilises kerosene and paraffin (OR 2.88, 95% CI 1.22–6.77) for heating and cooking were associated with increased S. aureus colonisation. However, exposure to farm animals (OR 0.3, 95% CI 0.11–0.83) as well as living in a house that uses wood and coal (OR 0.14, 95% CI 0.04–0.49) or outdoor fire (OR 0.31, 95% CI 0.13–0.73) were protective. Spa types t174 and t1476, and t272 and t1476 were dominant among urban and rural cases, respectively, but no main spa type was observed among controls, independent of geographic location. In urban cases, spa type t002 and t442 isolates were only identified in severe AD, t174 was more frequent in moderate AD, and t1476 in severe AD.

Conclusion

The strain genotype of S. aureus differed by AD phenotypes and rural-urban settings. Continued surveillance of colonising S. aureus lineages is key in understanding alterations in skin microbial composition associated with AD pathogenesis and exacerbation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06044-4.

Temporal Variation in Staphylococcus aureus Protein A Genotypes from Nose and Skin in Atopic Dermatitis Patients

BACKGROUND

Staphylococcus aureus colonization is associated with disease severity in patients with atopic dermatitis (AD).

OBJECTIVE

To investigate temporal variation in S. aureus protein A gene (spa)-types isolated from the nose and lesional skin and the correlation of spa-types with disease severity.

RESULTS

This study included 96 adult AD patients who were assessed at baseline (T0) and after a strict 2-week follow-up period (T1) in which treatment was standardized with a topical corticosteroid. Fifty-five different spa-types were detected in the nose and skin cultures. Seventy-three patients were colonized with S. aureus in the nasal cavity at both time points (persistent carriership), 59 of whom (81%) had identical spa-types over time. For skin samples, 42 (75%) of the 56 persistent skin carriers had identical spa-types over time. The same spa-type was carried in the nose and skin in 79 and 77% of the patients at T0 and T1, respectively. More severe disease was not associated with specific spa-types or with temporal variation in spa-type.

CONCLUSION

S. aureus strains in AD are highly heterogeneous between patients. The majority of patients carry the same spa-type in the nose and skin without temporal variation, suggesting clonal colonization within individual patients. No predominant spa-type or temporal variation is associated with increased disease severity.

Development of a human skin commensal microbe for bacteriotherapy of atopic dermatitis and use in a phase 1 randomized clinical trial

Staphylococcus aureus colonizes patients with atopic dermatitis (AD) and exacerbates disease by promoting inflammation. The present study investigated the safety and mechanisms of action of Staphylococcus hominis A9 (ShA9), a bacterium isolated from healthy human skin, as a topical therapy for AD. ShA9 killed S. aureus on the skin of mice and inhibited expression of a toxin from S. aureus (psmα) that promotes inflammation. A first-in-human, phase 1, double-blinded, randomized 1-week trial of topical ShA9 or vehicle on the forearm skin of 54 adults with S. aureus-positive AD (NCT03151148) met its primary endpoint of safety, and participants receiving ShA9 had fewer adverse events associated with AD. Eczema severity was not significantly different when evaluated in all participants treated with ShA9 but a significant decrease in S. aureus and increased ShA9 DNA were seen and met secondary endpoints. Some S. aureus strains on participants were not directly killed by ShA9, but expression of mRNA for psmα was inhibited in all strains. Improvement in local eczema severity was suggested by post-hoc analysis of participants with S. aureus directly killed by ShA9. These observations demonstrate the safety and potential benefits of bacteriotherapy for AD.

Colonization With Staphylococcus aureus in Atopic Dermatitis Patients: Attempts to Reveal the Unknown

Atopic dermatitis (AD) patients are massively colonized with Staphylococcus aureus (S. aureus) in lesional and non-lesional skin. A skin infection may become systemic if left untreated. Of interest, the incidence of multi-drug resistant S. aureus (MRSA) in AD patients is higher as compared to a healthy population, which makes treatment even more challenging. Information on the specific genetic background of S. aureus accompanying and/or causing AD flares would be of great importance in terms of possible treatment option development. In this review, we summarized the data on the prevalence of S. aureus in general in AD skin, and the prevalence of specific clones that might be associated with flares of eczema. We put our special interest in the presence and role of staphylococcal enterotoxins as important virulence factors in the epidemiology of AD-derived S. aureus. Also, we summarize the present and potentially useful future anti-staphylococcal treatment.

Genotypic Characteristics and Correlation of Epidemiology of Staphylococcus aureus in Healthy Pigs, Diseased Pigs, and Environment

China is one of the largest producers of pigs and pork in the world. However, large-scale studies on pig-associated Staphylococcus aureus in relation to healthy pigs, diseased pigs and environment are scarce. The objective of the present study was to characterize and compare S. aureus isolates from healthy pigs, diseased pigs and environment through antimicrobial susceptibility testing, multiple locus sequence typing, spa typing, and antimicrobial resistance gene screening. Results showed all isolates were susceptible to linezolid and vancomycin. However, 66.7% (104/156) isolates were multidrug-resistant by displaying resistance to three or more antibiotics and high rates of resistance to penicillin, tetracycline, clindamycin, and clarithromycin were observed. Of the 20 multilocus sequence types (STs) identified among the isolates, ST9, ST188, and ST7 were most commonly isolated from healthy pigs and environment, while ST1 was most commonly isolated from diseased pigs. In total, 17 spa types were represented among the isolates, while t4792 was most commonly isolated from diseased pigs and t899, t189 were most commonly isolated from healthy pigs and environment. In conclusion, the genotypic and epidemiology characteristics observed among the isolates suggest pigs and pork could be important players in S. aureus dissemination.

Strains of Staphylococcus aureus that Colonize and Infect Skin Harbor Mutations in Metabolic Genes

Staphylococcus aureus is the most common cause of skin and soft tissue infections, yet the bacterial genetic changes associated with adaptation to human skin are not well characterized. S. aureus strains isolated from patients with chronic skin colonization and intermittent infection were used to determine the staphylococcal genotypes or phenotypes associated with adaptation to human skin. We demonstrate that polymorphisms in metabolic genes, particularly those involved in the tricarboxylic acid cycle, the fumarate-succinate axis, and the generation of terminal electron transporters, are unexpectedly common. These skin-adapted strains activated glycolysis and hypoxia-inducible factor-1α, interleukin (IL)-1β, and IL-18 release from keratinocytes and promoted dermatopathology equivalent to a methicillin-resistant Staphylococcus aureus USA300 control in a murine model of infection. However, in contrast to USA300, a skin-adapted isolate failed to generate protection from a secondary infectious challenge. Within the context of human skin, there appears to be selection for S. aureus metabolic adaptive changes that promote glycolysis and maintain pathogenicity.

Temporal variation of Staphylococcus aureus clonal complexes in atopic dermatitis: a follow-up study

BACKGROUND

A strong link between disease severity and Staphylococcus aureus colonization of the skin has been reported in patients with atopic dermatitis (AD).

OBJECTIVES

To examine temporal variations in S. aureus colonization and S. aureus CC type in patients with AD, and to investigate links to disease severity, skin barrier properties and filaggrin gene (FLG) mutations.

METHODS

This was a follow-up study of a cohort of 101 adult patients with AD recruited from an outpatient clinic. Bacterial swabs were taken at baseline and follow-up from lesional skin, nonlesional skin and the nose. Swabs positive for S. aureus were characterized by spa and the respective clonal complex (CC) type was assigned. Patients were characterized with respect to disease severity [Scoring Atopic Dermatitis (SCORAD)], skin barrier properties [transepidermal water loss (TEWL), pH] and FLG mutations.

RESULTS

In total, 63 patients participated in a follow-up visit. Twenty-seven patients (43%) were colonized at both visits, 27 were colonized at only one visit and nine (14%) were not colonized at either visit. Of patients colonized at both visits, 52% remained colonized with the same CC type at follow-up. Change in CC type was related to an increase in SCORAD of 10·7 points; patients who carried the same CC type had a reduction in SCORAD of 4·4 points. Significantly higher skin pH was found in patients colonized at both visits, while change in CC type was not related to TEWL, pH or FLG mutations.

CONCLUSIONS

The data indicate that temporal variation in S. aureus CC type is linked to flares of the disease.

Staphylococcus aureus and Staphylococcus epidermidis strain diversity underlying pediatric atopic dermatitis

The heterogeneous course, severity, and treatment responses among patients with atopic dermatitis (AD; eczema) highlight the complexity of this multifactorial disease. Prior studies have used traditional typing methods on cultivated isolates or sequenced a bacterial marker gene to study the skin microbial communities of AD patients. Shotgun metagenomic sequence analysis provides much greater resolution, elucidating multiple levels of microbial community assembly ranging from kingdom to species and strain-level diversification. We analyzed microbial temporal dynamics from a cohort of pediatric AD patients sampled throughout the disease course. Species-level investigation of AD flares showed greater Staphylococcus aureus predominance in patients with more severe disease and Staphylococcus epidermidis predominance in patients with less severe disease. At the strain level, metagenomic sequencing analyses demonstrated clonal S. aureus strains in more severe patients and heterogeneous S. epidermidis strain communities in all patients. To investigate strain-level biological effects of S. aureus, we topically colonized mice with human strains isolated from AD patients and controls. This cutaneous colonization model demonstrated S. aureus strain-specific differences in eliciting skin inflammation and immune signatures characteristic of AD patients. Specifically, S. aureus isolates from AD patients with more severe flares induced epidermal thickening and expansion of cutaneous T helper 2 (T_H2) and T_H17 cells. Integrating high-resolution sequencing, culturing, and animal models demonstrated how functional differences of staphylococcal strains may contribute to the complexity of AD disease.

The Microevolution and Epidemiology of Staphylococcus aureus Colonization during Atopic Eczema Disease Flare

Staphylococcus aureus is an opportunistic pathogen and variable component of the human microbiota. A characteristic of atopic eczema (AE) is colonization by S. aureus, with exacerbations associated with an increased bacterial burden of the organism. Despite this, the origins and genetic diversity of S. aureus colonizing individual patients during AE disease flares is poorly understood. To examine the microevolution of S. aureus colonization, we deep sequenced S. aureus populations from nine children with moderate to severe AE and 18 non-atopic children asymptomatically carrying S. aureus nasally. Colonization by clonal S. aureus populations was observed in both AE patients and control participants, with all but one of the individuals carrying colonies belonging to a single sequence type. Phylogenetic analysis showed that disease flares were associated with the clonal expansion of the S. aureus population, occurring over a period of weeks to months. There was a significant difference in the genetic backgrounds of S. aureus colonizing AE cases versus controls (Fisher exact test, P = 0.03). Examination of intra-host genetic heterogeneity of the colonizing S. aureus populations identified evidence of within-host selection in the AE patients, with AE variants being potentially selectively advantageous for intracellular persistence and treatment resistance.

Turning the inside out: the microbiology of atopic dermatitis

Allergy is on the rise worldwide. The hygiene hypothesis of atopic diseases linked microbes with atopic dermatitis (AD) both as drivers and modulators of skin pathology. The earlier literature favoured an inside-outside model of AD where an immunological abnormality compounded by a gut microbiota dysbiosis is the primary event. Probiotic intervention trials with lactobacilli and bifidobacteria as well as the application of bifidogenic oligosaccharide prebiotics showed indeed promising clinical results, but no consistent gut microbiota dysbiosis could be linked with AD. An alternative hypothesis known as outside-inside model of AD considers a genetic skin barrier effect compounded by a skin microbiota dysbiosis as primary pathogenic event. Cultivation microbiology has demonstrated strong skin colonization with superantigen-encoding Staphylococcus aureus in AD patients; microbiota and molecular microbiome analyses demonstrated that S. aureus abundance fluctuates and parallels clinical symptoms. In a mouse model, δ-toxin of S. aureus induced mast cell degranulation, leading to AD-like symptoms. Mutant mice developing AD symptoms showed increased skin colonization with S. aureus; antibiotic treatment alleviated the symptoms. Clinical trials showed that various treatments reducing S. aureus skin load also reduced AD symptoms, suggesting S. aureus as a potential critical driver of AD and a target for antimicrobial interventions other than antibiotics.

Correlation Between Serum 25-Hydroxyvitamin D and Virulence Genes of Staphylococcus aureus Isolates Colonizing Children with Atopic Dermatitis

The skin of children with atopic dermatitis (AD) is colonized with Staphylococcus aureus more frequently than that of their peers. We investigated the prevalence of skin and nares colonization by S. aureus in children with AD, the virulence genes of the isolates, and their association with allergy, AD severity, and serum vitamin D (25(OH)D). This was an observational, cross-sectional study in a sample of children diagnosed with AD in two settings in Spain. The samples were collected in 2012. Swabs from affected skin and nares were taken for microbiologic culture. The prevalence of S. aureus and presence of 17 staphylococcal virulence genes were studied using polymerase chain reaction. A total of 114 patients with a mean age of 5.7 ± 4.1 (range 3 mos to 14 yrs) were included in the study. Swabs were taken from the skin of 113 individuals with AD and from the nares of 85; 28.3% had S. aureus on the skin, which was significantly associated with positive allergen-specific immunoglobulin E antibodies and higher Scoring Atopic Dermatitis (SCORAD) scores in the multivariate analysis. The presence of virulence factors tsst-1, eta, cna, aur, and sec in cutaneous S. aureus isolates was associated with lower serum levels of 25(OH)D. S. aureus on nasal swabs correlated with its presence on the skin and was associated with lower 25(OH)D levels. In conclusion, S. aureus colonization is associated with allergy and severity in AD, whereas certain virulence genes are associated with lower serum 25(OH)D levels.

Cutaneous Metastatic Undifferentiated Pleomorphic Sarcoma from a Mediastinal Sarcoma

Undifferentiated pleomorphic sarcoma, known as malignant fibrous histiocytoma, is a malignant neoplasm that arises in both soft tissue and bones. In 2002, the World Health Organization declassified malignant fibrous histocytoma as a formal diagnostic entity and renamed it 'undifferentiated pleomorphic sarcoma not otherwise specified.' It most commonly occurs in the lower extremities and rarely metastasizes cutaneously. We report a case of cutaneous metastatic undifferentiated pleomorphic sarcoma of the buttocks occurring in a 73-year-old man diagnosed with mediastinal sarcoma 4 years previously. He first noticed the mass approximately 2 months previously. Histological findings with immunomarkers led to a final diagnosis of cutaneous metastatic sarcoma from mediastinal undifferentiated pleomorphic sarcoma.

High prevalence of methicillin resistance and PVL genes among Staphylococcus aureus isolates from the nares and skin lesions of pediatric patients with atopic dermatitis

Staphylococcus aureus is highly prevalent among patients with atopic dermatitis (AD), and this pathogen may trigger and aggravate AD lesions. The aim of this study was to determine the prevalence of S. aureus in the nares of pediatric subjects and verify the phenotypic and molecular characteristics of the isolates in pediatric patients with AD. Isolates were tested for antimicrobial susceptibility, SCCmectyping, and Panton-Valentine Leukocidin (PVL) genes. Lineages were determined by pulsed-field gel electrophoresis and multilocus sequence typing (MLST). AD severity was assessed with the Scoring Atopic Dermatitis (SCORAD) index. Among 106 patients, 90 (85%) presented S. aureus isolates in their nares, and 8 also presented the pathogen in their skin infections. Two patients had two positive lesions, making a total of 10 S. aureusisolates from skin infections. Methicillin-resistant S. aureus(MRSA) was detected in 24 (26.6%) patients, and PVL genes were identified in 21 (23.3%), including 6 (75%) of the 8 patients with skin lesions but mainly in patients with severe and moderate SCORAD values (P=0.0095). All 24 MRSA isolates were susceptible to trimethoprim/sulfamethoxazole, while 8 isolates had a minimum inhibitory concentration (MIC) to mupirocin >1024 μg/mL. High lineage diversity was found among the isolates including USA1100/ST30, USA400/ST1, USA800/ST5, ST83, ST188, ST718, ST1635, and ST2791. There was a high prevalence of MRSA and PVL genes among the isolates recovered in this study. PVL genes were found mostly among patients with severe and moderate SCORAD values. These findings can help clinicians improve the therapies and strategies for the management of pediatric patients with AD.

Potential Immunoinflammatory Role of Staphylococcal Enterotoxin A in Atopic Dermatitis: Immunohistopathological Analysis and in vitro Assay

Background

The underlying mechanism of atopic dermatitis (AD) exacerbated by Staphylococcus aureus has not been established. However, we demonstrated recently that the majority of S. aureus strains colonized in the skin of Korean AD patients carried genes encoding staphylococcal enterotoxin A (SEA) and/or toxic shock syndrome toxin-1 (TSST-1).

Objective

To clarify the role of staphylococcal superantigen, SEA in AD.

Methods

With the lesional skin of 9 AD patients and normal looking skin of one healthy adult, we examined first the expression of SEA, staphylococcal enterotoxin B (SEB), and TSST-1 using immunohistochemical analysis. In addition, we investigated the effects of SEA on the expression of inflammation-related adhesion molecules and cytokines in human HaCaT keratinocytes and Human Umbilical Vein Endothelial Cells (HUVECs) by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and enzyme-linked immunosorbent assay.

Results

Staphylococcal protein A (SPA) and SEA were detected with increased immunoreactivity in AD patients. However, TSST-1 showed mild-to-moderate immunoreactivity in AD patients, whereas SEB was minimally detected. In the double immunofluorescence investigation, SEA and SPA were well co-localized. SEA induced upregulation of adhesion molecules and elicited inflammatory responses in HaCaT keratinocytes and HUVECs.

Conclusion

This study demonstrates the importance of SEA as an immunoinflammatory triggering factor of AD in Koreans.

Analysis of Colonization and Genotyping of the Exotoxins of Staphylococcus aureus in Patients with Atopic Dermatitis

BACKGROUND

The skin of atopic dermatitis (AD) patients has a high susceptibility to Staphylococcus aureus colonization, and the toxins produced by S. aureus may aggravate AD by acting as superantigens.

OBJECTIVE

The purpose of this study was to evaluate the relationship of the skin barrier function, colonization of S. aureus, and the clinical severity of AD. We also examined the predominant toxin genes produced in Korean AD patients.

METHODS

Thirty-nine patients with AD were evaluated for clinical severity and skin barrier function by using Severity Scoring of Atopic Dermatitis (SCORAD) index and transepidermal water loss (TEWL). S. aureus was isolated from the forearm, popliteal fossa, and anterior nares of AD patients (n=39) and age-matched controls (n=40); the toxin genes were analyzed by performing multiplex polymerase chain reaction.

RESULTS

TEWL showed a statistically significant correlation with clinical severity in patients with AD (p<0.05). TEWL was correlated with the number of S. aureus colonization sites and the presence of nasal colonization, but these results were not statistically significant. S. aureus strains were isolated in 64.1% of the 39 AD patients. The SCORAD index and AD severity were strongly correlated with the number of colonization sites. The predominant toxin gene found in AD patients was staphylococcal enterotoxin a (sea) only, which was produced in 52.6% of patients. The toxin genes sea and toxic shock syndrome toxin-1 (tsst-1) were found together in 42.1%, while tsst-1 only was found in 5.3% of the patients.

CONCLUSION

S. aureus strains were isolated in 64.1% of the 39 AD patients. Skin barrier function, as measured by TEWL, revealed a statistically significant correlation with clinical severity in AD patients. The SCORAD index and severity of AD was strongly correlated with the number of colonization. The most common toxin gene was sea in the Korean AD patients and this gene might have an important role in the pathogenesis of AD.

Clarifying the transmission route of Staphylococcus aureus colonizing the skin in early childhood atopic dermatitis

BACKGROUND

We previously found that skin-colonizing Staphylococcus aureus in early childhood atopic dermatitis (AD) originates predominantly from the patient's nose, whereas maternal transmission did not contribute substantially to colonization.

OBJECTIVE

To investigate the transmission route and definitive source of skin-colonizing S aureus in early childhood AD.

METHODS

A total of 527 children and 32 healthy teachers from 2 kindergartens and 1 elementary school were included in the study. Children were screened for AD and categorized into 3 groups (AD, borderline, and healthy). Samples were collected from 5 to 6 different body sites, including the skin, subungual spaces, and anterior nares. The identity of colonies apparent on mannitol salt agar plates was confirmed by polymerase chain reaction amplification of the nuc gene. The genotypic composition of cultured isolates was examined by pulsed-field gel electrophoresis and analyzed with a dendrogram.

RESULTS

The total colonization rate was higher in the AD group (34.6%) than in the borderline (21.1%) and healthy groups (25.4%). In the AD group, S aureus was more frequently cultured from the subungual areas (30.8%) than the anterior nares (19.2%). To assess self-contamination or recolonization, dendrogram analysis revealed that most isolate pairs (22/23) had the same pulsed-field gel electrophoresis pattern.

CONCLUSION

As with the anterior nares, the subungual spaces are important reservoir of skin-colonizing S aureus in early childhood AD. The transmission route for self-contamination or recolonization of S aureus appears to be from children's anterior nares to the skin through their own fingers. Child-to-child and/or teacher-to-child transmission in a classroom do not seem to be definite routes of S aureus transmission.

Temporal shifts in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis

Atopic dermatitis (AD) has long been associated with Staphylococcus aureus skin colonization or infection and is typically managed with regimens that include antimicrobial therapies. However, the role of microbial communities in the pathogenesis of AD is incompletely characterized. To assess the relationship between skin microbiota and disease progression, 16S ribosomal RNA bacterial gene sequencing was performed on DNA obtained directly from serial skin sampling of children with AD. The composition of bacterial communities was analyzed during AD disease states to identify characteristics associated with AD flares and improvement post-treatment. We found that microbial community structures at sites of disease predilection were dramatically different in AD patients compared with controls. Microbial diversity during AD flares was dependent on the presence or absence of recent AD treatments, with even intermittent treatment linked to greater bacterial diversity than no recent treatment. Treatment-associated changes in skin bacterial diversity suggest that AD treatments diversify skin bacteria preceding improvements in disease activity. In AD, the proportion of Staphylococcus sequences, particularly S. aureus, was greater during disease flares than at baseline or post-treatment, and correlated with worsened disease severity. Representation of the skin commensal S. epidermidis also significantly increased during flares. Increases in Streptococcus, Propionibacterium, and Corynebacterium species were observed following therapy. These findings reveal linkages between microbial communities and inflammatory diseases such as AD, and demonstrate that as compared with culture-based studies, higher resolution examination of microbiota associated with human disease provides novel insights into global shifts of bacteria relevant to disease progression and treatment.

Colonization with community-acquired methicillin-resistant Staphylococcus aureus in children with atopic dermatitis: a cross-sectional study

BACKGROUND

Bacterial infection with Staphylococcus aureus is a common complication of atopic dermatitis (AD). The incidence of community-acquired methicillin-resistant S. aureus infection (MRSA) in the AD population is unknown.

OBJECTIVES

This study aimed to assess the prevalence of S. aureus and MRSA in pediatric patients with AD, to compare disease severity, and to characterize the clonal diversity of the isolates.

METHODS

We carried out a prospective, cross-sectional study of 200 patients with AD. The severity of AD was defined as mild, moderate, or severe depending on a composite AD severity score. A swab was taken from the nares of each patient and another from affected skin or folds. Genotyping of all S. aureus isolates was conducted by polymerase chain reaction (PCR) amplification of the S. aureus protein A (spa) gene.

RESULTS

According to the severity score, 66.5% of subjects were ranked as having mild AD, 29.5% as having moderate and 4% as having severe AD. Staphylococcus aureus colonization was seen in 61.5% of all patients, represented by 43.7% of skin swabs and 48% of nares swabs. Only one of the isolations represented MRSA. Older age and higher AD severity scores were associated with S. aureus colonization (P = 0.03 and P < 0.001, respectively). No significant associations were noted for attendance at day care, family members with frequent skin infections, or family members working in healthcare. Isolates from spa CC015 were cultured in 19.2% of patient samples. The single MRSA culture showed a new spa type that belonged to CC127.

CONCLUSIONS

The results of this study confirm a high rate of S. aureus colonization of pediatric patients with AD. The low rate of MRSA requires further proof from larger prospective studies.

Colonizing features of Staphylococcus aureus in early childhood atopic dermatitis and in mothers: a cross-sectional comparative study done at four kindergartens in Daegu, South Korea

BACKGROUND

Colonization of Staphylococcus aureus is well known to be an aggravating factor for the flare-up of atopic dermatitis (AD), yet few studies have been done on its spread in families with childhood AD.

OBJECTIVE

To evaluate the characteristic features of skin-colonizing S aureus and to identify the source of S aureus in early childhood AD.

METHODS

Forty-four subjects with AD, 51 borderline (BD) subjects, and 36 normal controls (NC) aged 3-6 years and their mothers were recruited from four different kindergartens. After comparing the positive culture rate of S aureus in three different groups of children and their mothers, we determined if there is a possibility of intrafamilial transmission between the children with AD and their mothers using polymerase chain reaction and pulsed-field gel electrophoresis.

RESULTS

A high prevalence (72.7%) of S aureus colonization was found in the AD group compared with the BD and NC groups. However, the prevalence rate of S aureus in the mothers who had children with AD was not significantly higher than in the mothers from the BD and NC groups. Based on the pulsed-field gel electrophoresis results, the cutaneous re-colonization of S aureus in childhood AD appears to have been primarily originating from the patients' noses, and maternal origin does not appear to substantially contribute to S aureus transmission in early childhood AD.

CONCLUSIONS

Since the cutaneous colonization of S aureus in early childhood AD predominantly originated from the patients' own noses, the maternal transmission route does not appear to contribute substantially to the colonization of S aureus in early childhood AD.

Identification of major clonal complexes and toxin producing strains among Staphylococcus aureus associated with atopic dermatitis

Staphylococcus aureus promotes the onset and severity of atopic dermatitis (AD), which is exacerbated by superantigen toxins SEB and SEC. The genetic identity of these isolates, and their relationship to common hospital- or community-associated methicillin resistant S. aureus (HA-MRSA and CA-MRSA) has not been defined. We conducted spa typing, partial multi-locus sequence typing (MLST), and toxin profiling (seb, sec, lukS-PV) of S. aureus from 119 pediatric and 40 adult AD patients. MLST clonal complexes CC45, CC5, CC15, CC1, CC8 and CC30 accounted for 79% of isolates, representing the same major groups reported for nosocomial S. aureus in hospital intensive care units. The highest disease severity was associated with CC1, which was significantly greater relative to CC15 (p = 0.017) or CC30 (p = 0.040), but with no significant difference relative to CC45, CC5 or CC8. Although there were two few lukS-PV, seb or sec isolates to infer a role in disease severity, CC45 was identified as a source of SEC producing strains, and lukS-PVL was associated with a small number of CC5 pediatric isolates. CC1 harbored the only CA-MRSA that was identified, and was a source of isolates that expressed both seb and sec, and closely resembled the USA400 strain of CA-MRSA.