Superantigen Gene Profile of Staphylococcus Aureus Colonizing Egyptian Pediatric Patients with Atopic Dermatitis : Relationship to Disease Severity and Multi-Drug Resistance

Abstract

Background: Eczematous skin of atopic dermatitis (AD) is highly susceptible to infection and colonization by Staphylococcus aureus and the superantigen toxins can worsen the condition. Objectives: To assess the colonization of Egyptian pediatric AD patients with S. aureus and to characterize the superantigen gene profile of isolates in relation to severity and to presence of multiple drug resistant (MDR) strains. Methodology: The study included 53 AD pediatric patients and 45 controls. Severity of AD was assessed by scoring atopic dermatitis (SCORAD) index. Swabs were collected to isolate S. aureus. Isolates were subjected to multiplex PCR reactions for detection of six superantigen genes and to antimicrobial susceptibility tests by disc diffusion method. Results: Colonization with S. aureus was significantly higher (P < 0.0001) in AD children compared to controls and was significantly associated (P= 0.001) with severity. Superantigen genes were detected in 30.1% of isolates. The most prevalent genes were sea (64.5%), seb (32.3%), sec (6.5%) and tsst-1 (3.2%). Multidrug resistance was found in 63.1% of strains. Severity of AD was significantly higher with strains harboring superantigen genes (P=0.04) and with MDR strains (P=0.0002). Among methicillin resistant S. aureus (MRSA), seb was the most prevalent superantigen gene (37.5%), while sea was most prevalent in methicillin-susceptible S. aureus (MSSA) (20%), MDR (23.1%) and non MDR isolates (13.2%).Conclusion: Superantigen genes and multidrug resistance are common in S. aureus colonizing AD patients and are associated with severity. More attention should be paid at performing antimicrobial susceptibility testing before antibiotic therapy.