The objective was to analyse the genetic lineages of Staphylococcus aureus recovered from nasal and skin samples of atopic dermatitis (AD) paediatric patients, and to characterize the antimicrobial resistance phenotype-genotype and the immune-evasion-cluster (IEC) type of isolates. Forty S. aureus isolates from 35 patients (skin: 26; nasal samples: 14) were characterized. Isolates were submitted to spa-, agr- and multilocus sequence typing. All S. aureus strains analyzed were methicillin-susceptible (MSSA). High genetic diversity was detected among the 40 MSSA isolates (especially among skin isolates), with detection of 27 different spa-types, 20 sequence-types and 16 clonal complexes (CCs). Lineages CC30 and CC5 were predominant among nasal isolates (71% vs 23% skin). Thirteen different CCs were detected among skin isolates, with detection of clades CC1, CC9 and CC398. Antimicrobial resistance rates detected were higher in skin than in nasal isolates, especially for macrolides, aminoglycosides, lincosamides and mupirocin. MSSA strains were characterized into five IEC-types, being A, B and F the predominant ones. MSSA strains of lineages CC45 and CC5 were detected in almost all cases in AD patients with severe Scoring Atopic Dermatitis (SCORAD) and lineages CC8, and CC30 in those with mild or moderate one. As conclusion, high-clonal-diversity was detected among MSSA from AD patients, especially in skin-isolates. Colonization with S. aureus of some CCs seems more associated with AD severity than other lineages.

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.

Background/Objectives The association between atopic dermatitis, body weight and serum lipid levels is not well known, and very few studies have examined this relationship in children. Methods Children (n = 239) under 14 years old participated in this prospective cross‐sectional study. The following variables were recorded: age, gender, weight, height, atopic dermatitis severity, serum levels of total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol and triglycerides. Results Mean body mass index was slightly higher in atopic dermatitis patients than healthy controls and significantly higher in atopic dermatitis patients aged 0–2 years (atopic dermatitis, 16.7 ± 4.6; controls, 15.7 ± 1.3; P = 0.04) and 12–14 years (atopic dermatitis, 24.9 ± 5.3; controls, 20.6 ± 3.4; P = 0.03). Among atopic dermatitis patients, body mass index was significantly higher in those with severe atopic dermatitis in the 9–12 (P = 0.03) and 12–14 (P = 0.01) years groups. Mean serum lipid levels were higher in patients with severe atopic dermatitis than in the atopic dermatitis group as a whole. These differences reached statistical significance for total cholesterol (P = 0.04) and triglycerides (P = 0.02). Conclusion The prevalence of overweight, obesity and dyslipidemia is greater in children with atopic dermatitis than in age‐matched healthy counterparts.

Background Previous studies have linked low serum vitamin D (VD) or 25‐hydroxyvitamin D (25(OH)D) levels with increased severity of atopic dermatitis (AD) in children. Objective To investigate the association between serum VD (25(OH)D) levels and AD and AD severity, considering the influence of diet and sun exposure. Methods We performed a prospective cross‐sectional study of healthy controls and children diagnosed with AD. Participants were recruited between January 2011 and December 2012, and the following parameters were assessed: age, sex, body mass index (BMI), AD severity, Fitzpatrick skin type, asthma and rhinitis history, dietary VD intake, daily potential sun‐induced VD production, sunscreen use, 25(OH)D and IgE serum levels, and results of the ImmunoCAP Phadiatop Infant test. Results The study population consisted of 105 healthy controls and 134 AD patients. Serum 25(OH)D levels were significantly lower in moderate and severe AD than in mild AD, although this association was only significant for patients with light Fitzpatrick skin type (mean(SD) 36.7 (11.9) ng/mL; moderate 28.8 [11.5] ng/mL; and severe 27.6 [12.1] ng/mL, P = .045). Logistic regression analysis revealed a positive association between severe AD and both positive ImmunoCAP Phadiatop test and BMI. Conclusion Our data support an association between VD deficiency and AD severity only in patients with light complexion.