PNNL

Abstract

A partial-thickness epidermal explant model was colonized with GFP-expressing S. aureus and the pattern of S. aureus biofilm growth was characterized using electron and confocal laser scanning microscopy. Oxygen concentration in explants was quantified using microelectrodes. The relative effective diffusivity and porosity of the epidermis were determined using magnetic resonance imaging, while hydrogen peroxide (H2O2) concentration in explant media was measured by using microelectrodes. Secreted proteins were identified and quantified using MSE mass spectrometry. We found that S. aureus biofilm grows predominantly in sebum-rich areas around hair follicles and associated skin folds. Dissolved oxygen was selectively depleted (2-3 fold) in these locations, but the relative effective diffusivity and porosity did not change between colonized and control epidermis. Histological analysis revealed keratinocyte damage across all the layers of colonized epidermis after four days of culture. The colonized explants released significantly (P