A Prospective Multi-site Case Series Incorporating Bacterial Fluorescence Information into the UPPER/LOWER Infection Checklists

Introduction: The UPPER/LOWER infection checklists highlight signs and symptoms of local/superficial infection (UPPER) and deep infection (LOWER) to assist clinicians in identifying and distinguishing between infection levels. All checklist items are possible host responses to high levels of bacteria. This case series evaluated the utility of incorporating real-time information on high bacteria loads, via real-time bacterial fluorescence imaging, into these checklists. 

Methods: This was a prospective, 11-patient, multi-site case series. Chronic wound patients being seen by study clinicians for the first time were assessed with the checklists to look for signs or symptoms of local/superficial infection (UPPER) and deep infection (LOWER); three symptoms present from either checklist was the threshold for infection-positive. Fluorescence images of their wound were then acquired to look for regions of bacteria, which uniquely fluoresce red or cyan under the violet light of the imaging device.  

Results: Three wounds were considered infected based on UPPER/LOWER checklists. Fluorescence images were positive for bacterial presence in all three wounds. In four wounds, adding bacterial fluorescence information brought the wound past the UPPER checklist threshold, influencing treatment decisions. Culture results later confirmed fluorescence findings. In the remaining four wounds, three checks were not obtained even with fluorescence positive images. Interestingly, one of these wounds exhibited bacterial (red) fluorescence that was entirely removed with debridement. A post-debridement swab was also negative, suggesting surface bacteria contaminants only and supporting the lack of UPPER/LOWER signs and symptoms in this patient. 

Conclusions: These cases suggest that the UPPER/LOWER checklists and fluorescence images work in a complementary manner, with each providing additional, unique information not captured by the other. Therefore, incorporation of a bacteria-specific component into these infection checklists had high utility, identifying additional patients in need of topical antimicrobial treatment (4/10). Larger studies to validate these findings would be warranted.