Are there predominant strains and toxins of Staphylococcus aureus in atopic dermatitis patients? Genotypic characterization and toxin determination of S. aureus isolated in adolescent and adult patients with atopic dermatitis

Abstract

The colonization of Staphylococcus aureus is one of the most important aggravating factors of atopic dermatitis (AD). Until now, the importance of S. aureus in AD and a positive correlation between colonization with S. aureus and clinical severity/skin barrier function has been demonstrated. The aim of this study was to determine whether there are certain clones of S. aureus which colonize the skin of AD patients. For this purpose, the genotype of S. aureus isolated from AD patients was examined by newly-developed typing methods. With 36 strains of S. aureus isolated from 35 patients with AD, spa typing, multi-locus sequence typing (MLST), and staphylococcal toxin gene assay by multiplex polymerase chain reaction, were performed. Clinical severity and skin barrier function were evaluated with eczema area and severity index (EASI) and with transepidermal water loss (TEWL). Among 36 strains of S. aureus, 14 sequence types (ST) and 20 spa types were identified, suggesting a very heterogeneous genetic composition of S. aureus and the absence of a prevailing genotype in S. aureus colonized with AD patients. Furthermore, there was no specific genotype of S. aureus which was associated with the clinical severity of AD or skin barrier dysfunction. A toxin gene assay, however, showed the predominance of S. aureus strains carrying sea and/or tsst-1. To the best of our knowledge, this is the first report to show the genetic composition of S. aureus strains isolated from AD patients determined by sequence-based typing methods.

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

“…The heterogeneity of the 16S rRNA sequences supports earlier studies demonstrating absence of predominant S. aureus clones or biotypes (Hoeger et al 1992;Lomholt et al 2005;Kim et al 2009;Yeung et al 2011). …”

Superantigen Profile of Staphylococcus Aureus Isolates from Patients with Atopic Dermatitis in Sri Lanka

“…Our results indicate that a very high percentage (88%) of SA strains isolated from patients with AD is positive for genes that encode SAgs, which supports their role in the pathogenesis of AD. This high percentage is compatible with the findings from previous studies from other cohorts where 70 -100% of strains isolated were positive for SAg genes [4][5][6]22].…”

“…Several recent studies have not observed a significant association of any particular SAg with clinical disease severity of AD [4,5,14,15]. Yet these studies have also shown high percentages of SAg gene positive SA in patients with AD.…”

“…SA strains producing SAgs encoded by the enterotoxin gene cluster (SEG, SEI, SElM, SElN, SElO) are commonly isolated from patients with AD [4,14]. Although high percentages of SAg producing SA strains have been isolated from patients with AD, a significant association of any particular SAg with clinical disease severity has not been observed [4,5,14,15]. However, sensitization to staphylococcal superantigens has found to be associated with higher disease severity [16,17].…”

“…It is one of the commonest skin diseases affecting around 10% to 30% of children and 2-3% of adults [1][2][3]. Studies have shown that superantigen producing strains of Staphylococcus aureus (SA) could be isolated from over 70% of patients with AD [4][5][6]; Superantigens (SAgs) of SA have been shown to play an important role in inducing skin inflammation in AD. They are thought to aggravate the disease by multiple pathways including activation of T cells that are important in the disease pathogenesis of AD.…”