Abstract: Objective To study the bacteriological characteristics and the pathogenesis of Staphylococcus aureus (S. aureus) on eczema and atopic dermatitis (AD). Methods A multi-center randomized, double blind bacteriological study on the lesions and non-lesional skin of patients with eczema (207) and AD (119) were carried out. The antibiotic sensitivity and the bacteriophage typing were performed on all the S. aureus isolated from the patients. Results There were statistical differences in the positive rate of the culture, the ratio and the colonization of S. aureus between the lesion and the non-lesional skin in eczema (P<0.01). The positive rate of culture and the colonization of S. aureus in the lesions was significantly higher than those in the non-lesional skin (P<0.01) in 119 AD patients. The results of bacteriophage typing of 141 strains of S. aureus isolated were as follows:type I, II, III, V and miscellaneous type accounted for 6.3%, 7.0%, 3.5%, 0.7% and 1.4% respectively, 56% of the strains were unable to be typed. In 26 strains of MRSA, 9 strains (6.3%) were of mixture type. The results of antibiotic sensitivity tests indicated that the MIC, MIC₅₀ and MIC₉₀ of mupirocin for S. aureus were the lowest among those of other 5 topical antibiotics. Mupirocin was also sensitive to all different phage types of S. aureus, even to MRSA and MRCNS strains. Conclusions The bacteria (especially S. aureus) infection are important in the pathogenesis of eczema and AD, the combination of topical corticosteroid and antibiotics may be beneficial in the treatment of eczema and AD.

Key words: Eczema, Dermatitis, atopic, Staphylococcus aureus, Microbial sensitivity tests