Jornal de Pesquisa em Dermatologia Clínica e Experimental
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Abstrato

Correlation of Twenty Virulence Genes of Staphylococcus aureus with Severity of Atopic Dermatitis in Children as Compared to Healthy Individuals

Anja Jochmann, Suzanne Hower, Stephen Davis, Jan Izakovic and Lisa RW Plano

Principles: Patients with Atopic Dermatitis (AD) have a higher susceptibility for colonization and infection with Staphylococcus aureus. Virulence factors of S. aureus may modulate the host immune response and affect the clinical course of infection.

Methods: Bacterial cultures were obtained from AD patients and uninfected controls. PCR and DNA sequence analysis were used to determine microbial surface components recognizing adhesive matrix molecules (MSCRAMM) patterns, staphylococcus protein A (spa) types, and the presence of genes for 20 virulence factors and for methicillin resistance (mecA). Virulence factor gene patterns from AD associated S. aureus were compared with gene patterns from the control group, as well as with S. aureus previously obtained from infected skin lesions not associated with AD.

Results: The gene encoding chemotaxis inhibiting protein (chp) was found more frequently in S. aureus isolated from the uninfected control group (p=0.0003). Isolates of AD patients were more likely to carry the gene sea (p=0.0327), which encodes for an enterotoxin known to act as a superantigen. Prevalence of eta, etb and chp were significantly associated with organisms isolated from non-AD infected lesions (eta: p=0.0003, etb: p=0.0001, chp: p=0.012) There was no difference in the prevalence of any MSCRAMM gene pattern or 19 additional virulence factors genes analyzed, and none were associated with severity of the AD lesions. MRSA SCCmec type IVa made up approximately 8% of both AD and control isolates.

Conclusions: The genotypes of S. aureus strains colonizing AD patients do not differ significantly from the genotypes of strains colonizing healthy individuals. Isolates infecting patients without AD express significantly more eta and etb and therefore seem to be more virulent to overcome the intact skin barrier.