A quantitative culture study of Staphylococcus aureus in adolescent and adult patients with atopic dermatitis using the contact-plate sampling technique

Background: The stratum corneum of the skin of patients with atopic dermatitis (AD) is highly susceptible to colonization by various bacteria, including Staphylococcus (S.) aureus. Because the frequency of bacterial colonization is significantly higher, skin barrier function against bacterial invasion appears to be significantly disrupted in AD. S. aureus colonization in AD is thought to be important in the development and aggravation of eczematous skin lesions. Over the past decades, there have been several quantitative methods of cutaneous bacterial culture from the skin; the swab method, scrub method, tape method and contact plate method. Objective: The purpose of this study was to evaluate the effectiveness of the contact-plate sampling technique as a quantitative culture method of S. aureus in atopic dermatitis. Method: The subjects were 24 patients with AD and 24 age-matched normal controls. S. aureus was sampled at 4 evaluation sites (neck forearm abdomen, popliteal fossa) of AD patients and normal controls using the contact-plate sampling technique. We also checked skin barrier function by measuring the transepidermal water loss (TEWL). Results: Based on the data, we found that the number of S. aureus colonies in the samples from AD patients was significantly higher than from normal controls (p<0.05, 4 sites respectively). Also, TEWL at the 4 evaluation sites of AD patients was significantly higher than in normal controls (p<0.05, 4 sites respectively). However, S. aureus colonization did not usually show significant correlation with TEWL. Conclusion: The contact-plate sampling technique provides a reliable qualitative and quantitative culture method of S. aureus, which is inexpensive and convenient so can be used in both children and within a busy clinic.