| Objective: Microbial infection is observed to trigger and exacerbate the conditions of patients with atopic dermatitis (AD) and eczema (EC), and S aureus, as the most common pathogenic bacterium ,is considered to play a certain role in the inflammation. S aureus strains isolated from AD subjects release superantigens such as staphylococcal enterotoxin A and B (SEA, SEB), which can cause continued T-cell activation and release of pro-inflammatory mediators. The purpose of this study is to detect status of S aureus colonization on skin and serum levels of antibodies against staphylococcal enterotoxin B (SEB) for patients with AD or EC,and to analyze microbial infection, especially S aureus infection how to induce immunologic disturbance and its role in pathogenesis of AD and EC, and offer laboratory data and background to apply antibiotics in treatment of EC and AD.Methods: The patients with AD or EC of three regions (Nanjing City, Guangzhou City, Chongqing City) were enrolled in a multi-centered, random, double-blinded and controled study , and the study group was treated with mupirocin and hydrocortisone butyrate,while the control group was treated with matrix of mupirocin and hydrocortisone butyrate for 28 days. Bacteria samples were taken from both skin lesions and unaffected skin before treated and then were cultured and identified. Serum was taken before and after the treatment to detect specific antibodies.Enzyme-linked immunoabsordent assay (ELISA) was used to detect serum levels of specific IgG and IgM against SEB and total IgE.Bridged streptavidine-biotin method was used to detect the serum level of specific IgE against SEB.Results: l.As to EC, the positive rates of bacteria isolation (p=0.000), S aureus isolation (p=0.000) and its density (p=0.002) were significantly higher in lesion skin man in unaffected skin; as to AD, the positive rates of bacteria isolation (p=0.000) , S aureus isolation (p=0.000) and its density (p=0.016) also were significantly higher in lesion skin than in unaffected skin.2.Level of total IgE of AD was significantly higher than that of normal control (NC, p=0.001) and EC (p=0.003), and it's also higher in EC than in NC(p=0.006).Level of SEE IgE of AD was significantly higher than that of NC (p=0.019) and EC (p=0.048) too, but no significant difference was seen between NC and EC (p=0.883). Levels of SEE IgM of both AD (p=0.012) and EC (p=0.000) were higher than that of NC, but no significant difference was seen between AD and EC(p=0.088). Level of SEE IgG had no significant differences among the three groups(p=0.806). At the end of the treatment, the level of SEE IgM decreased significantly both in AD (p=0.003) and EC (p=0.000), while no significant difference was seen between the study group and the control group (p>0.05). And neither total IgE nor SEB-specific IgE was correlated with the severity of AD (p>0.05).Conclusion: S aureus is confirmed to colonize on both lesion skin and unaffected skin of patients with AD or EC, and density of S aureus in lesion skin is higher than unaffected skin, which strongly suggest that S aureus is involved in pathogenesis of AD and EC. SEB-specific IgG and IgM have been produced during the exposure to S aureus, but may not be protective against SEE. The higher level of SEB-specific IgM in AD and EC also suggest that colonization of S aureus is involved in pathogenesis of both AD and EC.SEB also act as one kind of common allergens in AD, stimulating specific IgE synthesis and releasing, which is confirmed to involve hi exacerbation of allergic inflammation. However, the level of SEB-specific IgE did not correlate with the severity of AD, suggesting colonization of S aureus and its enterotoxins are not the only pathogen of AD and EC.Because colonization of S aureus is very commom and its function in exacerbation of AD and EC is confirmed,, it's reasonable to apply antibiotics in treatment of AD and EC.
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