title: Severe atopic dermatitis is associated with a high burden of environmental Staphylococcus aureus.
abstract: BACKGROUND
  About 90% of patients with atopic dermatitis (AD) are colonized with Staphylococcus aureus. S. aureus worsens AD by secreting superantigens and structural molecules within the cell wall that induce skin inflammation. Therefore, S. aureus in the home may contribute to persistent skin inflammation and disease severity.
  
  
  OBJECTIVE
  To quantify S. aureus burden in homes of participants with AD of varying severities.
  
  
  METHODS
  Participants with mild (n=18), moderate (n=14), severe (n=15), and no AD (n=15), collected dust from their bed and bedroom floor, and from their home vacuum cleaner bag. DNA was extracted from dust samples, and the S. aureus-specific femB gene was quantified using quantitative real-time PCR. Data was log-transformed, and then statistically analysed with anova, student's t-test, and Spearman's r.
  
  
  RESULTS
  Participants with severe AD (geometric mean: 14.67 pg/mg dust) had significantly more S. aureus DNA in their bed dust than those with moderate (0.41 pg/mg dust, P<0.0001), mild (1.42 pg/mg dust, P=0.0051), and no AD [0.09 pg/mg dust, P<0.0001 (t-test)]. Similar patterns were observed for dust from the bedroom floors and vacuum bags. S. aureus DNA was highest in dust from beds as compared with bedroom floors or vacuum bags (medians: 1.51, 0.69, 0.21 pg/mg dust, respectively; P=0.007). Eczema Area and Severity Index scores correlated with S. aureus DNA from the bed (Spearman's r=0.7263; P=0.0004) and floor (0.6846; P=0.0002) dust, but not with the vacuum bag dust (0.3783; 0.0684).
  
  
  CONCLUSIONS
  In the home and especially the bedroom, higher levels of S. aureus may contribute to disease severity and persistence in AD patients.
authors.affiliation: Division of Allergy and Immunology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Leung
authors.forename: A M
authors.initials: AM
authors.lastname: Schiltz
authors.forename: C F
authors.initials: CF
authors.lastname: Hall
authors.forename: A H
authors.initials: AH
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000328:Adult; D001512:Bedding and Linens; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D003876:Dermatitis, Atopic / Q000382:microbiology* / Q000503:physiopathology; D004391:Dust / Q000032:analysis*; D004485:Eczema / Q000382:microbiology / Q000503:physiopathology; D005430:Floors and Floorcoverings; D006798:Housing; D006801:Humans; D007223:Infant; D016133:Polymerase Chain Reaction / Q000379:methods; D012720:Severity of Illness Index; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D004269:DNA, Bacterial; D004391:Dust