Figure 1.

Schematic representation of establishing the mixed infection model of S. aureus and S. epidermidis. S. aureus and S. epidermidis were inoculated onto the surface of a fully-differentiated, stratified 3D epidermal model following two different protocols: (I) S. aureus and S. epidermidis were pre-mixed and inoculated simultaneously; (II) S. epidermidis was inoculated 4h prior to S. aureus. Culture media were replenished at 24h and collected at 24h and 48h to monitor the extracellular levels of LDH, IL-1α and IL-1β. At 48h, S. aureus and S. epidermidis on the surface of the 3D epidermal model were harvested and then enumerated by plate count. Intact epidermal tissues along with the Staphylococci were also preserved and processed for the analysis of bacterial distribution and migration using confocal fluorescence microscopy.