Skin colonization of Staphylococcus aureus in atopic dermatitis patients seen at the National Skin Centre, Singapore.

OBJECTIVE: This prospective study sought to determine the bacterial colonization rates on eczematous and non-eczematous skin and nasal mucosa of patients with atopic dermatitis attending a tertiary dermatologic referral clinic in Singapore. The colonization rates were evaluated according to age, sex, race, and severity of dermatitis compared with controls. The results may help to determine whether antibiotics should be considered in the treatment of atopic dermatitis. PATIENTS: Patients, of any age, presenting with atopic dermatitis at the subsidized clinic of the National Skin Centre, Singapore, between 23 August 1996 and 14 September 1996, were included in the study.
RESULTS: Thirty-three patients with atopic dermatitis were seen at the outpatient clinic during the study period. Staphylococcus aureus was isolated in 69.7% of the eczematous lesions and in 42.4% of non-eczematous skin of patients with atopic dermatitis. S. aureus was isolated in 53% of patients with mild dermatitis, and in 100% with moderate and severe dermatitis. The nasal carriage rate of S. aureus was higher in atopic dermatitis patients (51.5%) than in non-atopics (35%) (not significant). S. aureus was isolated in 42% of non-eczematous skin in atopics compared with only 5% in the control group (p = 0.003). In patients with atopic dermatitis, all S. aureus isolated was sensitive to cloxacillin, cephalexin, clindamycin, and co-trimoxazole; 92% was sensitive to erythromycin, but only 13% was sensitive to penicillin and ampicillin. In the control group, all S. aureus isolated was sensitive to cloxacillin, cephalexin, erythromycin, clindamycin, and co-trimoxazole, but only 13% was sensitive to penicillin and ampicillin, and 87% to tetracycline.
CONCLUSIONS: This study confirmed that the skin of patients with atopic dermatitis was more frequently colonized with S. aureus than that of non-atopics. The more severe the dermatitis, the higher the rate of colonization. S. aureus is also more of than present in non-eczematous skin of atopics than of non-atopics. There is also a higher percentage of S. aureus nasal carriage in patients with atopic dermatitis than in non-atopics. Hence antibiotics may have a role in the treatment of atopic dermatitis. Because 87% of S. aureus is resistant to penicillin and ampicillin, antibiotics such as cloxacillin and cephalexin should be used to eradicate S. aureus in the skin of atopic dermatitis individuals.