Acta Dermato-Venerelogica Issue No 7, 2017 97-7CompleteContent | Page 12

802 INVESTIGATIVE REPORT Variation in Staphylococcus aureus Colonization in Relation to Disease Severity in Adults with Atopic Dermatitis during a Five- month Follow-up Mikael ALSTERHOLM 1 , Louise STRÖMBECK 1 , Annika LJUNG 2 , Nahid KARAMI 2 , Johan WIDJESTAM 2 , Martin GILLSTEDT 1 , Christina ÅHREN 2 and Jan FAERGEMANN 1 1 Department of Dermatology and Venereology, Sahlgrenska University Hospital, and 2 Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden The aim of this study was to monitor Staphylococcus aureus colonization and disease severity in adults with atopic dermatitis (AD) during 5 months. Twenty-one patients attended 3 visits each for severity SCORing of Atopic Dermatitis (SCORAD) assessment, quantitative cultures from the skin and conventional cultures from the anterior nares, tonsils and perineum. S. aureus iso- lates were typed for strain identity with pulsed-field gel electrophoresis (PFGE). Seventy-one percent of patients were colonized with S. aureus on lesional skin at least once. Density (colony-forming units (CFU)/ cm 2 ) was higher on lesional skin than on non-lesional skin (p  < 0.05). Density on lesional skin and number of colonized body sites were positively correlated with SCORAD (p  = 0.0003 and p  = 0.007, respectively). Per- sistent carriers of the same strain on lesional skin had higher mean SCORAD index than intermittent/non- carriers (36.3 and 17.1, respectively, p  = 0.002). The results show a temporal correlation between several aspects of S. aureus colonization and disease severity in AD raising the question of the importance of this in pathogenesis and treatment. Key words: atopic dermatitis; S. aureus; SCORAD; PFGE. Accepted Apr 4, 2017; Epub ahead of print Apr 4, 2017 Acta Derm Venereol 2017; 97: 802–807. Corr: Mikael Alsterholm, Department of Dermatology and Venereology, Sahlgrenska University Hospital, Gröna Stråket 16, SE-413 45 Göteborg, Sweden. E-mail: [email protected] S taphylococcus aureus is a gram-positive bacteria that can act as a human commensal on the skin as well as a causative agent in several types of skin and soft tissue infections. The carriage pattern of S. aureus in healthy subjects has been studied extensively (1). The nasal cavity, skin, perineum and pharynx can all carry S. aureus, with the anterior nares being the most common site of carriage. Carriage rate on the skin ranges from 5% to 30% depen- ding on body site and whether the individual is a persistent nasal carrier. In contrast, lesional skin of patients with atopic dermatitis (AD) is reported to be colonized with S. aureus in 70% of cases (2). Flare-ups of AD are often associated with S. aureus super-infection, and one treat- ment strategy is the use of topical or oral antimicrobials (3). While there is a strong link between acute S. aureus infection of the skin and increase in disease activity, the doi: 10.2340/00015555-2667 Acta Derm Venereol 2017; 97: 802–807 role of colonization in the pathogenesis and maintenance of AD remains unclear. A currently favoured theory in AD pathogenesis is the “outside-in” hypothesis, whereby an impaired epidermal barrier, allowing penetration of environmental substances into the skin, is described as the starting point in an early march towards atopy (4). As a consequence there is sensi- tization to microbial products and allergens, which in turn triggers an immune dysregulation followed by inflamma- tion of the skin. In 1990, Williams et al. (5) demonstrated a positive correlation between S. aureus density on lesional skin and the severity of AD, later confirmed by numerous other investigators (6). In recent years, several studies have demonstrated a higher disease activity in AD associated with the presence of S. aureus and sensitization to staphylococcal toxins (7–12). Lomholt et al. (13) reported that a change from one colonizing strain of S. aureus to another was as- sociated with increased disease activity in children with AD. In view of this, it is somewhat surprising that there is little, and also conflicting, data to support the efficacy of anti-staphylococcal interventions in patients, primaril y children, with clinically non-infected AD (14–16). The failure to demonstrate convincing clinical benefit could be due to a lack of high-quality randomized controlled trials, as concluded in a Cochrane review on this topic (17). An- other explanation could lie in the selection of patients for interventional studies. Presumably, the pattern of S. aureus colonization varies between patients. It could be suggested that only those with persistent and high-density colonization are likely to benefit from anti-staphylococcal interventions. Variation in S. aureus colonization over time in rela- tion to severity of AD has, to our knowledge, rarely been described in adult patients. Therefore, we investigated S. aureus carriage in adults with AD at repeated visits during a 5-month follow-up period to investigate whether any temporal shifts in S. aureus carriage occurred and if this could be related to disease severity measured with the SCORAD index. METHODS Patients The study was conducted at the Department of Dermatology and Venereology, Sahlgrenska University Hospital and at the Depart- ment of Infectious Diseases, Institute of Biomedicine, The Sahl- grenska Academy at the University of Gothenburg in 2010–2012. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2017 Acta Dermato-Venereologica.