Non-invasive assessment of healing of bacteria infected and uninfected wounds using optical coherence tomography

Abstract

Bacterial infection is one of the main predisposing factors for the delay in wound healing. To facilitate a timely decision for correct therapy, it is important to accurately monitor the morphological changes in the infected wounds using noninvasive tools. In the present study, we have explored the use of optical coherence tomography (OCT) for monitoring the healing of superficial wounds infected with Staphylococcus aureus in mice under in vitro and in vivo conditions and studied the changes in collagen birefringence in the infected wounds. The tape stripping method was used for generating superficial skin wounds in mice and wounds were infected with S. aureus. For in vitro studies, infected and uninfected wound tissues were resected, back scattered intensity and birefringence changes in collagen during wound healing were studied on the 2, 4 and 10th day of postinfection using polarization-sensitive (PS) OCT and images were compared with histology. Real-time OCT was used for studying the kinetics of healing of infected wounds under in vivo conditions. From the PS-OCT images, different phases of wound healing such as inflammation, reepithelialization and collagen remodeling could be identified. The edematic regions appeared prominent in infected wounds. Compared with uninfected wounds, reepithelization and collagen remodeling phases of wound healing were delayed significantly in the infected wounds. These changes were comparable with the different stages of wound healing observed under in vivo conditions. OCT imaging can provide a rapid assessment of the morphological changes associated with bacteria-infected and uninfected wounds and thereby aid in timely treatment planning.