Prevalence of community-acquired methicillin-resistant Staphylococcus aureus and antibiotic resistance in patients with atopic dermatitis in Porto Alegre, Brazil

Authors

  • Vanessa Petry MD,

    Corresponding author
    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
    • Correspondence

      Vanessa Petry, md

      Rua Mostardeiro 291/305

      CEP 90430–000 Moinhos de Vento

      Porto Alegre, Rio Grande do Sul

      Brazil

      E-mail: vpetry@hotmail.com

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  • Caroline Lipnharski MD,

    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Giancarlo R. Bessa MD,

    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Vera B. Silveira MD,

    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Magda B. Weber PhD,

    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Renan R. Bonamigo PhD,

    1. Department of Dermatology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Pedro A. d'Azevedo PhD

    1. Department of Microbiology, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
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  • Funding: This study was supported by the Conselho Nacional de Tecnologia e Desenvolvimento Científico (CNPq) and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS).

  • Conflicts of interest: None.

Abstract

Background

Atopic dermatitis (AD) is a skin manifestation of atopy caused by hyperreactivity to various antigens. Studies have shown that 60–100% of patients with this condition present with colonization by Staphylococcus aureus. Given increasing rates of antimicrobial resistance, the sensitivity to antimicrobials of S. aureus colonizing atopic patients has been investigated. Cross-sectional studies worldwide suggest that the prevalence of methicillin-resistant S. aureus infection (MRSA) in the AD population varies from 0% to 30.8%.

Objectives

The objectives of this study were to determinate the prevalence of S. aureus and MRSA in patients with AD in two dermatologic centers in Porto Alegre, Brazil.

Methods

A total of 91 patients with AD attending two dermatologic centers in Porto Alegre were enrolled in this study from December 2009 to July 2011. Two skin swabs were taken from each patient, one from the nares and the other from a non-infected eczematous skin lesion. The swabs were sent to the laboratory, where standard procedures to isolate bacteria and identify S. aureus, antimicrobial resistance, and sensitivity patterns were carried out. The severity of AD was defined using the Eczema Area and Severity Index (EASI).

Results

Of the 91 patients sampled, 67 (73.6%) patients were found to be positive for S. aureus colonization. Nasal swabs were positive in 55 (60.4%) patients, lesional swabs in 44 (48.4%) patients, and both lesional and nasal swabs were positive in 32 (35.2%) patients. Patients with positive swabs had a higher mean ± standard deviation EASI score [mean (9.1 ± 8.8)] compared with patients with negative swabs (3.9 ± 3.6) (= 0.002). None of the 91 patients showed any evidence of MRSA infection. Overall, nearly 32% of the S. aureus isolated from nasal swabs and 36.40% of the S. aureus isolated from lesional swabs was resistant to erythromycin.

Conclusions

The results of this study confirm a high rate of S. aureus colonization in pediatric patients with AD and indicate a relevant association between colonization and high EASI score. No MRSA was found in cultures from this sample of patients in southern Brazil. Nearly one-third of isolates were identified as resistant to erythromycin, an antibiotic that is commonly used in pediatric patients.

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