[A study of the single nucleotide polymorphism fragments of the AUR gene metalloprotease strains of Staphylococcus aureus isolated from the skin of patients with atopic dermatitis].

Objective: to study the heterogeneity of internal fragments of the aur gene coding a proteolytic enzyme aureolysin in strains of Staphylococcus aureus with different enzymatic activity, which were allocated with the affected skin of patients with atopic dermatitis.
Materials and Methods: the study included 125 patients aged 1 to 35 years old with the diagnosis of atopic dermatitis. 100 clinical strains of Staphylococcus aureus were studied in monoculture. Identification of the strains of Staphylococcus aureus in skin was performed using standard classical methods. Specific biochemical microtests using a set of APIs Staph 20 (bioMerieux SA, France) were conducted to confirm the obtained results. Reference strains of S. aureus ATCC 29213, NCTC at 8.325 were used. Specific aur gene loci were detected by the method of multiplex polymerase chain reaction. Proteolytic activity was determined by the ability to split the substrate (human IgG, Sigma) into fragments using as inhibitors of matrix 0.01-0.1M solutions of sodium EDTA. The sequencing of the amplified areas of aur gene, including the preliminary stages of separation and purification of DNA, was performed by Syntol, Moscow.
Results: different strains of the conservative plot amplicon fragment of aur contains up to 9 polymorphic nucleotides. The index of the nucleotide diversity for proteolytic active strains was less (Pi = 0.04) than for proteolytically inactive (Pi = 0.07), p < 0.05. It should be noted that all proteolytically active strains were isolated from the skin of patients with high and moderate severity of atopic dermatitis (67.8 +/- 5.4 points on SCORAD scale) with erythematous form of the disease. The inactive strains were allocated in patients of older age with reduced severity of atopic dermatitis (with the dry form of skin lesions).