Methicillin-resistant Staphylococcus aureus colonization and disease severity in atopic dermatitis: a cross-sectional study from South India.

Background: Colonization by methicillin-resistant Staphylococcus aureus (MRSA) in atopic dermatitis is little studied but has therapeutic implications. It may have a role in disease severity given the additional virulence factors associated.

Aims: Our aims were to record the proportion of patients with MRSA colonization in atopic dermatitis and to ascertain if any association exists between MRSA colonization and disease severity.

Methods: An observational cross-sectional study involving children aged≤12 years with atopic dermatitis attending the outpatient department of Government Medical College, Kottayam was conducted. Socio-demographic data, exacerbating factors and risk factors for hospital care-associated MRSA were documented. Extent of atopic dermatitis was recorded using a standardized scale (Eczema Area Severity Index, EASI). Skin swabs were taken from anterior nares and the worst affected atopic dermatitis sites for culture and sensitivity.

Results: Of the 119 subjects recruited during the study period (November 2009-April 2011), Staphylococcus aureus was isolated from 110 (92.4%) patients and MRSA from 30 (25.21%) patients. A total of 18 patients with MRSA had risk factors for healthcare associated-MRSA. The patients whose cultures grew MRSA were found to have significantly higher EASI score when compared to those patients colonized with methicillin sensitive Staphylococcus aureus (P < 0.01). Presence of Staphylococcus aureus, early age of onset, presence of food allergies, seasonal exacerbation and inadequate breastfeeding did not seem to influence disease severity.

Conclusions: There is a high degree of prevalence of MRSA (25.2%) in atopic dermatitis and presence of MRSA is associated with increased disease severity. Further studies are needed to validate these findings.