Pulsed-field gel electrophoresis of Staphylococcus aureus isolates from atopic patients revealing presence of similar strains in isolates from children and their parents

Determination of nasal carriage and skin colonization, antimicrobial susceptibility and genetic relatedness of Staphylococcus aureus isolated from patients with atopic dermatitis in Szczecin, Poland

BACKGROUND

Atopic dermatitis (AD) is one of the most frequent chronic and inflammatory skin condition. AD is characterized by damaged epidermal barrier, xerosis and pruritus of eczematous skin lesions which tend to flare. The duration and frequency of exacerbation of AD symptoms markedly affects the quality of patient life. AD results from the interplay between host genetics, immunity, and environmental factors, however the detailed pathogenesis of this disease is still not entirely cleared. Furthermore, disturbances of the skin microbiota and skin functional impairment predispose to secondary skin infections. Staphylococcus aureus colonizes skin and mucous membranes of 20 to 80% of healthy individuals and of 90% of patients with AD in whom this bacterium is accounted as an important AD exacerbating factor. It is also proven, that S. aureus nasal carriage significantly increases the risk for self-transmission and endogenous infection. In the current study the presence of S. aureus either in nasal vestibule and on lesioned skin of 64 patients with AD enrolled in 10-year autovaccination program was determined. The genetic relatedness of 86 S. aureus isolated from patients nose and skin using Pulsed Field Gel Electrophoresis (PFGE) and antimicrobial susceptibility of all strains to methicillin, erythromycin, clindamycin, mupirocin, gentamicin, amikacin, tetracycline, chloramphenicol and cotrimoxazole was also evaluated.

RESULTS

In total 23 PFGE genotypes and 24 unique patterns were distinguished. 34 patients were S. aureus nasal carriers. Simultaneous presence of S. aureus in nose and on affected skin was found in 16 carriers colonized by indistinguishable or potentially related S. aureus vs 2 carriers colonized with non-related S. aureus in nasal vestibule and on skin. 4 isolates were methicillin resistant (MRSA) among which 3 showed constitutive MLSB resistance phenotype and remaining one was resistant to tetracycline and chloramphenicol. In 4 isolates inducible MLSB resistance phenotype was found, one of them was additionally resistant to tetracycline. 7 S. aureus were mupirocin resistant among them 3 - isolated from one patient, were resistant simultaneously to tetracyclines and chloramphenicol. 7 strains demonstrated resistance to chloramphenicol and susceptibility to all tested antimicrobial agents. The susceptibility to gentamicin, amikacin and cotrimoxazole among all examined S. aureus was confirmed.

CONCLUSION

The obtained results indicated non-clonal structure of S. aureus circulating in AD patients. PFGE results showed the clonal-structure of vast majority of S. aureus isolated from nose and skin from nasal carriers what may prove the autoinfection in these patients. All examined patients the moderate or strong severity of AD was reported. Susceptibility to most antibiotics among isolated strains was also observed.

Bacterial zoonoses transmitted by household pets and as reservoirs of antimicrobial resistant bacteria

Numerous individuals are committed to growing pet creatures like cats, dogs, and rats etc., pay care for them and as a result of this, there's a boost of their populace in advanced culture. The close interaction between family pets and individuals offers ideal conditions for bacterial transmission. Distinctive sorts of antimicrobial agents are exploited for animal husbandry and studies have revealed that many bacteria have attained confrontation against them viz., Staphylococcus intermedius, Escherichia coli, methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococci and multidrug-resistant Salmonella typhi etc. and a few of these are a prospective for zoonotic transmission. In the current review, the attention has been paid on how household pets, especially dogs disperse the antimicrobial resistance in contrast to that of food animals. A lot of evidences are accessible on food animals and nation-wide scrutiny programmes solely hub on food animals; therefore, for steerage antimicrobial use policy in small animal veterinary exercise as well as for gauging the chance of transmission of antimicrobial resistance to humans' statistics on pet animals are sincerely needed. Transmission of such organisms, especially pathogenic staphylococci, occurs between pets, owners, and veterinary staff, and pets can act as reservoirs of such bacteria; this may additionally have an impact on the use of antimicrobials in human medicine. There is a need to generate statistics concerning each the levels of carriage of such microorganism in pets and the risk factors associated with the switch of the microorganism to human beings who have contact with infected pets, as nicely as to improve hygiene measures in veterinary practice.

Association between nasal and nasopharyngeal bacterial colonization in early life and eczema phenotypes

Background

An association has been reported between early life Staphylococcus aureus nasal carriage and higher risk of childhood eczema, but it is unclear whether this relationship is causal and associations with other bacterial species are unclear.

Objective

To examine the associations of early life nasal and nasopharyngeal bacterial carriage with eczema phenotypes, and the direction of any associations identified.

Methods

Among 996 subjects of a population‐based prospective cohort study, nasal swabs for Staphylococcus  aureus, and nasopharyngeal swabs for Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae were collected and cultured from age 6 weeks to 6 years. Never, early, mid‐, late transient and persistent eczema phenotypes were identified from parental‐reported physician‐diagnosed eczema from age 6 months until 10 years. Multinomial regression models and cross‐lagged models were applied.

Results

Staphylococcus aureus nasal carriage at 6 months was associated with an increased risk of early transient and persistent eczema (OR (95% CI): 2.69 (1.34, 5.39) and 4.17 (1.12, 15.51)). The associations between Staphylococcus aureus nasal carriage and eczema were mostly cross‐sectional, and not longitudinal. No associations of Staphylococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenza nasopharyngeal bacterial carriage with eczema and eczema phenotypes were observed (OR range (95% CI): 0.71 (0.35, 1.44) to 1.77 (0.84, 3.73)).

Conclusions

Early life Staphylococcus aureus nasal carriage, but not Staphylococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenza nasopharyngeal carriage, was associated with early transient and persistent eczema. Staphylococcus aureus nasal carriage and eczema were mostly cross‐sectionally associated, and not longitudinally, making a causal relationship in either direction unlikely.

[Occupationally acquired MRSA colonization and occupational dermatological assessments (BK-No. 3101 in the German list of Occupational Diseases) : Analysis of the DGUV documentation and expert opinion on a case with work-related MRSA-triggered atopic dermatitis]

BACKGROUND

Person-to-person transmitted infectious diseases can cause occupational diseases (OD). These are subsumed as BK-No. 3101 in the German list of OD which applies for individuals with a considerably higher risk for infection as a consequence of their professional activity compared to the general population.

OBJECTIVES

The special medical and insurance law aspects of a work-related MRSA colonization are presented using the example of an expert opinion case and an evaluation of the BK reports of suspected occupational disease (BK No. 3101) of the German Social Accident Insurance (DGUV).

PATIENTS AND METHODS

The BK documentation of the DGUV from 2007-2012 and the patient cohort from the Department of Dermatology, University Hospital Erlangen, presenting for expert assessment from 2007-2012 were retrospectively analysed for human-to-human transmitted infectious diseases of the skin (BK-No. 3101).

RESULTS

Person-to-person transmission of infectious diseases of the skin is rare in the field of occupational dermatology. In the DGUV cohort, suspected BK-No. 3101cases amounted to 2.6% of all notified cases; recognized BK-No. 3101 cases accounted for 4.2% of all recognized cases, amongst which 9 were caused by MRSA. In contrast to a symptomatic infection, an asymptomatic MRSA colonization is not being recognized as BK-No. 3101. Bacterial superantigens can trigger atopic dermatitis (AD). In particular cases, occupationally acquired MRSA can elicit AD and may justify classification as an OD (BK-No. 3101).

CONCLUSIONS

Early detection of MRSA colonization and eradication are necessary for rehabilitation. Management of skin diseases due to infectious diseases within the framework of OD is presented.

Diversity of Staphylococcus pseudintermedius in carriage sites and skin lesions of dogs with superficial bacterial folliculitis: potential implications for diagnostic testing and therapy

BACKGROUND

Staphylococcus pseudintermedius is genotypically diverse within the canine population and multiple strains may colonize individual dogs at any given time. If multiple strains with distinct antimicrobial resistance profiles are present in superficial bacterial folliculitis (SBF), sampling a single skin lesion for culture and antimicrobial susceptibility testing (AST) might be inadequate to select effective therapy.

HYPOTHESIS/OBJECTIVES

To investigate S. pseudintermedius diversity in carriage sites and lesions of dogs with SBF.

ANIMALS

Fourteen dogs with SBF.

METHODS

Staphylococcus pseudintermedius isolates obtained from perineum, gingiva and four to six skin lesions per dog were subjected to pulsed-field gel electrophoresis (PFGE) and AST to assess diversity between lesions. For two dogs, 14-16 isolates per lesion were included in the analysis to assess diversity within lesions.

RESULTS

Analysis of one isolate per lesion revealed one to four strains displaying unique PFGE profiles, and up to three unique antimicrobial resistance (AMR) profiles for each dog. Multiple pustules from the same dog always harboured the same strain, whereas papules, crusts and collarettes did not. Up to four strains with distinct AMR profiles were isolated from the same lesion in two dogs. In 12 dogs, at least one carriage site strain also was represented in lesions.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lesions of SBF may harbour multiple S. pseudintermedius strains with distinct antimicrobial resistance profiles. Pustules are the best target for bacterial culture. It remains unclear whether isolation of different strains from other lesion types is a consequence of contamination or co-infection by multiple strains.

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.

[Comparative Genotyping of Staphylococcus aureus Strains Isolated from Skin Lesions, Nasal Cavities, and Feces of Children with Atopic Dermatitis]

Background

The lesion of skin of the majority atopic dermatitis patients is chronically colonized by bacteria belonging to the species Staphylococcus aureus. Topical antibacterial and anti-inflammatory therapy treatment are often ineffective due to fast recolonization by S. aureus and exacerbation of allergic process.

Aims

Our aim was to determine a frequency of S. aureus colonization in skin lesions, mucous membranes of the nasal cavity and intestine of children with atopic dermatitis, to compare the genotypes of Staphylococcus aureus strains isolated from different biotopes of atopic dermatitis patients, and to clarify whether the intestinal and nasal cavities microbiota may act as a source of S. aureus recolonization of skin lesions.

Materials and Methods

Bacteriological examination of fecal samples, skin, and nasal swabs was conducted in 38 atopic dermatitis patients. The pure bacterial cultures of S. aureus were identified using API Staph (Biomerieux, France) and Vitek 2 MS (Biomerieux, France). Isolates of S. aureus were subjected to genotyping by analysis of rRNA internal 16S-23S rRNA spacer regions and high resolution melting analysis (HMR) of polymorphic spa X-regions.

Results

99% S. aureus strains were successfully identified using MALDI-TOF mass-spectrometry. S. aureus cultures were isolated from all biotopes in 31,6% of children, from skin and nasal cavities — in 42% of cases, from skin and feces — in 2,6% of cases, only from skin — in 10,5%, from nasal cavities and feces — in 2,6%, and only from nasal cavities — in 2,6% of cases. In 8% of children, S. aureus was not detected in any of the biotopes. Genotyping of the isolates enabled the detection of 17 different genotypes. A match between the genotypes of skin and nasal strains, and skin and fecal strains was observed in 88% and 61% of the cases respectively.

Conclusions

The observed a high-frequency matching genotypes suggests the possibility of migration of S. aureus strains inside biotopes in humans and the absence of specialization to colonization of any of the niches.

Development of in vitro resistance to chitosan is related to changes in cell envelope structure of Staphylococcus aureus

The bacterial cell envelope is believed to be a principal target for initiating the staphylocidal pathway of chitosan. The present study was therefore designed to investigate possible changes in cell surface phenotypes related to the in vitro chitosan resistance development in the laboratory strain S. aureus SG511-Berlin. Following a serial passage experiment, a stable chitosan-resistant variant (CRV) was identified, exhibiting >50-fold reduction in its sensitivity towards chitosan. Our analyses of the CRV identified phenotypic and genotypic features that readily distinguished it from its chitosan-susceptible parental strain, including: (i) a lower overall negative cell surface charge; (ii) cross-resistance to a number of antimicrobial agents; (iii) major alterations in cell envelope structure, cellular bioenergetics and metabolism (based on transcriptional profiling); and (iv) a repaired sensor histidine kinase GraS. Our data therefore suggest a close nexus between changes in cell envelope properties with the in vitro chitosan-resistant phenotype in S. aureus SG511-Berlin.

Atopic dermatitis in children: clinical features, pathophysiology, and treatment

Atopic dermatitis (AD) is a chronic, relapsing, highly pruritic skin condition resulting from disruption of the epithelial barrier and associated immune dysregulation in the skin of genetically predisposed hosts. AD generally develops in early childhood, has a characteristic age-dependent distribution and is commonly associated with elevated IgE, peripheral eosinophilia, and other allergic diseases. Medications such as antihistamines have demonstrated poor efficacy in controlling AD-associated itch. Education of patients regarding the primary underlying defects and provision of a comprehensive skin care plan is essential for disease maintenance and management of flares.

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.

Atopic dermatitis: optimizing the topical therapy

Goal. Determination of the skin microbiocenosis in patients with atopic dermatitis (AtD) and evaluation of the treatment efficacy for AtD patients using isoconazole nitrate and diflucortolone valerate. Materials and methods. The authors assessed skin microflora in 168 AtD patients. Skin scrapes were obtained for further microscopy, and inoculation tests were performed. As many as 59 secondary AtD patients were treated with a combination of isoconazole nitrate and diflucortolone valerate as well as methylprednisolone aceponate, drugs from the DARDIA line. The treatment efficacy was evaluated clinically based on the SCORAD index as well as skin microrelief assessed with the use of the Visioscan BW30 video camera. After the treatment with Travocort, the nature and degree of skin colonization with AtD microorganisms were also assessed. Results. The efficacy of topical administration of isoconazole nitrate and diflucortolone valerate as well as methylprednisolone aceponate, drugs from the DARDIA line, was confirmed for the treatment of secondary AtD patients. Conclusion. Making antibiotics and antimycotic agents a part of the complex therapy of secondary AtD patients seems to be expedient for eliminating pathogenic microorganisms.

Enterotoxin-producing staphylococci cause intestinal inflammation by a combination of direct epithelial cytopathy and superantigen-mediated T-cell activation

BACKGROUND

Enterotoxin-producing Staphylococcus aureus may cause severe inflammatory intestinal disease, particularly in infants or immunodeficient or elderly patients. They are also recognized to be associated with sudden infant death syndrome. Little is known, however, about mucosal responses to staphylococci.

METHODS

The mucosal lesion in three infants with staphylococcal enterocolitis was assessed by immunohistochemistry and electron microscopy. The organisms underwent extensive molecular analysis. Their toxins were assessed for capacity to induce T-cell activation and host mucosal responses examined by in vitro organ culture. Epithelial responses were studied by coculture with HEp-2 and Caco-2 cells.

RESULTS

Intestinal biopsies from the patients showed marked epithelial damage with mucosal inflammation. The three staphylococci, representing two distinct clones, were methicillin-sensitive, producing SEG/I enterotoxins and Rho-inactivating EDIN toxins. Their enterotoxins potently activated T cells, but only whole organisms could induce in vitro enteropathy, characterized by remarkable epithelial desquamation uninhibited by tacrolimus. EDIN-producing staphylococci, but not their supernatants, induced striking cytopathy in HEp-2 epithelial cells but not in Caco-2 cells. Although HEp-2 and Caco-2 cells produced similar IL-8, CCL20, and cathelicidin LL37 responses upon bacterial exposure, only Caco-2 cells expressed mRNA for the β-defensins HBD2 and HBD3, while HEp-2 cells were unable to do so.

CONCLUSIONS

Staphylococci induce enterocolitis by a combination of direct enterocyte cytopathy mediated by EDIN toxins, disrupting the epithelial barrier, and enterotoxin superantigen-induced mucosal T-cell activation. Gut epithelial production of β-defensins may contribute to host defense against invasive staphylococcal disease.

Infant colonization by Staphylococcus aureus: role of maternal carriage

Infant colonization by Staphylococcus aureus has not been adequately investigated. In this study, we aimed to define determinants associated with the carriage of S. aureus in early infancy. Serial nasal swabs were collected from 128 infants and their mothers at months 0, 6, and 12 postpartum. S. aureus isolates were characterized by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), spa typing, and the presence of chromosomal mecA and of Panton-Valentine leukocidin (PVL) genes. S. aureus was isolated in 17.7% and 15.7% of swabs from infants and mothers, respectively. Carriage rates were higher in infants with carrier mothers, non-smoking mothers, and many siblings. Persistent carriage rates were higher in infants with carrier or non-smoking mothers. S. aureus typing revealed identical strains in 10/15 investigated infant-mother pairs. Among 19 investigated S. aureus isolates from infants, ten harbored mecA and two harbored PVL genes, and these determinants were concomitantly present in isolates from mothers. Resistance to methicillin was 43.6% among all isolates from infants. In conclusion, isolates from infants were commonly identical to isolates from their mothers, pointing to a principal role of maternal carriage in S. aureus colonization in infants.

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.

The infectious aspects of atopic dermatitis

Atopic dermatitis is characterized by Staphylococcus aureus colonization and recurrent skin infections. In addition to an increased risk of invasive infections by herpes simplex or vaccinia viruses, there is ample evidence that microbial pathogens, particularly S aureus and fungi, contribute to the cutaneous inflammation of atopic dermatitis. The authors describe recent developments in the pathogenesis of atopic dermatitis in relation to the role of microbial pathogens. Understanding how microbial pathogens interact or evade the cutaneous immunity of atopic dermatitis may be crucial in preventing infections or cutaneous inflammation in this disease.

Recent insights into atopic dermatitis and implications for management of infectious complications

Atopic dermatitis (AD) is a common complex disease that frequently follows a chronic relapsing course and affects the quality of life of patients and families in a significant manner. New insights into the pathophysiology of AD point to an important role of structural abnormalities in the epidermis combined with immune dysregulation. Patients with AD have a unique predisposition to colonization or infection by a number of microbial organisms, most notably Staphylococcus aureus and herpes simplex virus. A multipronged approach directed at healing or protecting the skin barrier and addressing the immune dysregulation is necessary to improve the likelihood of successful outcomes.

Prevalence and molecular characteristics of Staphylococcus aureus isolates colonizing patients with atopic dermatitis and their close contacts in Singapore

BACKGROUND

Staphylococcus aureus colonization is an established pathogenic factor for disease flare in atopic dermatitis (AD).

OBJECTIVES

We conducted a study to investigate the colonization of S. aureus in patients with AD and their close contacts in order to evaluate the possibility of intrafamilial transmission. We sought to determine the distribution of the bacterial virulence factors and their correlation with disease severity.

METHODS

Nasal swabs and skin swabs (patients with AD only) were taken from patients with AD aged 2-21 years and their close contacts, seen at the National Skin Centre from January to March 2007. All S. aureus isolates were typed using multilocus variable-number tandem-repeat fingerprinting (MLVF) and screened for virulence factors via polymerase chain reaction (PCR) analysis. AD severity was determined by the SCORAD index.

RESULTS

A total of 34 patients with AD and 55 close contacts were recruited. Thirty-one (91%) patients were colonized with S. aureus. Twenty-five (45%) of their close contacts were also colonized, and MLVF showed a high concordance of S. aureus isolates in index patients and their close contacts. On multivariate analysis, patients with a moderate SCORAD were more likely to be colonized by enterotoxin B-positive S. aureus (P = 0.027). No virulence factor was significantly associated with a severe SCORAD.

CONCLUSIONS

The prevalence of S. aureus colonization was high among patients with AD and their close contacts. However, no predominant isolate of S. aureus was found to be associated with AD. The presence of superantigen B is possibly associated with moderate rather than severe disease in our population.