Hindawi Publishing Corporation Clinical and Developmental Immunology Volume 2011, Article ID 718708, 7 pages doi:10.1155/2011/718708 Clinical Study Molecular and Immunological Characterization of Staphylococcus aureus in Pediatric Atopic Dermatitis: Implications for Prophylaxis and Clinical Management Chiara Pascolini, 1 JoLinda Sinagra, 1 Simone Pecetta, 2 Valentina Bordignon, 1 Alessandra De Santis, 1 Laura Cilli, 1 Viviana Cafiso, 3 Grazia Prignano, 1 Bruno Capitanio, 1 Claudio Passariello, 2 Stefania Stefani, 3 Paola Cordiali-Fei, 1 and Fabrizio Ensoli 1 1 Clinical Pathology and Microbiology Laboratory and Pediatric Dermatology Division, San Gallicano Dermatology Institute, 00144 Rome, Italy 2 Department of Public Health and Infectious Diseases, University La Sapienza, 00185 Rome, Italy 3 Department of Microbiology, University of Catania, 95124 Catania, Italy Correspondence should be addressed to Grazia Prignano, prignano@ifo.it Received 8 July 2011; Accepted 1 September 2011 Academic Editor: K. Blaser Copyright © 2011 Chiara Pascolini et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. S. aureus represents a critical cofactor in atopic dermatitis (AD). In this paper, the prevalence of S. aureus infection/colonization was evaluated in 117 children as well as in their cohabitants, in order to assess the value of S. aureus characterization in predicting disease onset and severity and in providing indications for prophylaxis. Results showed that children with AD as well as their cohabitants had a significantly greater incidence of S. aureus infection/colonization as compared to controls. The genetic characterization showed a virtual identity of the bacteria strains collected at different sites of the patients with those found in the cohabitants, suggesting both a direct transmission between the nasal reservoir and the lesions in the same atopic subject and a risk for reinfection within family cohabitants. These data stress the need of preliminary laboratory assessment and posttherapy control in both AD patients and their close contacts for effective S. aureus eradication. 1. Introduction Atopic dermatitis (AD) is an inflammatory disease affecting the skin and characterized by impaired epidermal barrier function and cutaneous inflammation [1, 2]. It is clinically characterized by an early onset, mostly occurring before 5 years of age [3]. The prevalence of AD has increased in indus- trialized countries during the past three decades, and among Italian schoolchildren the estimated prevalence is presently of about 5.8% [4]. The eczematous skin of the patients is highly susceptible to bacterial colonization, and Staphylococcus aureus (S. aureus) represents the most frequent isolate [5– 8]. S. aureus is a Gram-positive opportunistic bacterium that, although part of the normal flora of the skin, can give rise, as a consequence of clonal evolution, to virulent strains characterized by the expression of virulence factors and the acquisition of resistance to a number of different drugs including β-lactams [9]. S. aureus infection appears to play an important role in the pathogenesis of AD by either causing or exacerbating skin inflammation [10–13]. In fact, S. aureus toxins have potent superantigenic properties (e.g., staphylococcal enterotoxin SEA, SEB, SEC, SED, and toxic shock syndrome toxin (TSST-1)) and may induce monocytes and lymphocytes activation, which in turn are induced to produce several inflammatory cytokines [14, 15]. In a healthy skin, this process causes an inflammatory reaction with a clinical outcome similar to that seen in AD [10]. Although the impact of S. aureus infection in the clinical manifestation of AD is still debated, antibiotic-corticosteroid combination therapy against S. aureus represents an impor- tant component of the therapeutic approach to AD [16] and appears effective against both the occurrence of secondary