Antibacterial and anti-biofilm effects of sodium hypochlorite against Staphylococcus aureus isolates derived from patients with atopic dermatitis

Abstract

Introduction

Atopic dermatitis (AD) is characterised by an increased susceptibility for skin infections. Staphylococcus aureus is reported to dominate in AD lesions and reports have revealed the presence of staphylococcal biofilms. These infections contribute to aggravating the eczema. Sodium hypochlorite is known to reduce bacterial load of skin lesions as well as disease severity in AD patients but the effect on biofilms is unknown.

Objectives

The aim of this study was to investigate the antimicrobial and anti-biofilm effects of sodium hypochlorite against S. aureus isolates derived from patients with AD.

Materials and Methods

Skin biopsy derived from infected AD patient was examined by scanning electron microscopy (SEM). Using radial diffusion assays, biofilm assays and confocal laser scanning microscopy, we assessed the effect of sodium hypochlorite on S. aureus isolates derived from lesional skin of AD patients.

Results

SEM revealed clusters of coccoid bacteria embedded in fibrin and extracellular substances at the skin of a patient with infected AD. At concentrations of 0.01-0.08%, sodium hypochlorite showed antibacterial effects against planktonic cells. Eradication of S. aureus biofilms in vitro was observed in concentrations ranging from 0.01% to 0.16%. Confocal laser scanning microscopy confirmed these results. Finally, when human AD skin was subjected to sodium hypochlorite in an ex vivo model, a dose of 0.04% reduced the bacteria derived from AD skin.

Conclusions

Sodium hypochlorite has antimicrobial and anti-biofilm effects against clinical S. aureus isolates. Our findings suggest usage of a higher concentration than currently used in bleach baths of skin-infected AD patients.

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