Transcription analysis of the extracellular adherence protein from Staphylococcus aureus in authentic human infection and in vitro.

BACKGROUND: Wound infections caused by Staphylococcus aureus are associated with significant morbidity and mortality. The staphylococcal extracellular adherence protein (Eap) has been shown to delay wound healing by interfering with host defense and angiogenesis, yet the expression of Eap in the human wound is required to exert these functions.
METHODS: A protocol was developed to determine eap transcription levels in vivo (human wounds) relative to those in vitro. In parallel, isolates derived from positive blood cultures were analyzed for eap transcription.
RESULTS: Transcription of eap was found in vivo as well as in vitro for all isolates, with eap transcription in vivo being significantly elevated relative to that in the in vitro cultures. In vivo, isolates from deep wounds yielded higher transcription than did those from superficial wounds, whereas in vitro transcription levels for blood culture isolates exceeded those for wound isolates.
CONCLUSION: This is the first comprehensive transcription analysis of S. aureus eap in authentic human wounds, and our findings support the hypothesis that Eap contributes to the development of chronic infections by interfering with wound-healing mechanisms. These findings open the door to a novel approach for exploring the complex in vivo interactions between bacteria and the host in such settings.