Bacterial fluorescence imaging as a predictor of skin graft integration in burn wounds

Split-thickness skin graft (STSG)¹ integration rates are susceptible to improvement. Infection and/or biofilm should be appropriately addressed prior to grafting to improve the likelihood of graft-take. Incorporating technological aids such as fluorescence (FL)² imaging (MolecuLight®), which accurately locates areas of bacterial loads above 10⁴ CFU/gr, for graft site assessment and preparation could yield better outcomes.

This single-center, prospective observational study included adult burn patients with previously infected wounds that had been deemed clinically and microbiologically clean and were therefore candidates for grafting. Prior to grafting, a FL imaging assessment (blinded to the surgical team) localized areas positive for moderate-high bacterial loads (>10⁴ CFU/gr). Intra-operatively, a standard swab sample from the recipient site was collected by the surgical team. Postoperatively, areas positive/negative for FL and areas of graft take and failure were overlapped and measured (cm²) over a 2D schematic. The performance and accuracy of FL imaging and swab sampling in relation to graft outcomes were assessed.

38 patients were enrolled in the study. The mean total body surface area (TBSA)³ involvement was 14.5 ± 12.4 % [range 0.8 - 40.2 %]. 25/38 of the subjects enrolled had complete graft take while 13 had partial graft losses. There were no total losses. FL-imaging was positive in 100 % of losses versus 31 % (4/13) of the swab microbiology. FL-imaging was found to have a sensitivity of 86 %, specificity of 98 %, PPV of 72 %, NPV of 99 %, and an accuracy of 94 % for predicting any type or range of graft loss in the entire cohort. Meanwhile, the sensitivity of microbiology from swab samples was 30 %, with a specificity of 76 %.

FL imaging is an accurate method for assessing recipient sites and predicting the outcome of a skin graft among burn patients. These findings suggest that FL imaging can inform better decision-making surrounding grafts that may lead to better outcomes.

Level IIA, Therapeutic study.