Optotracers to study biofilms in host-relevant systems and non-conventional treatments using Staphylococcus aureus wound biofilms as a case study

Optotracers have a wide-range of applications in the detection, visualization, and characterization of biofilms. More recently, optotracers have been used in antibiotic susceptibility assays for biofilms and for the detection of biomarkers in clinical biofilm infections. This is particularly important, given that the field is increasingly focused on the evaluation of novel anti-biofilm agents and the study of biofilms in host-relevant systems. Given this, the possibility of using optotracers for an expanded set of biofilm focus areas is important to explore. In this study, we examine the application of the optotracer EbbaBiolight 680 to study biofilms in a host-relevant system and for the evaluation of a non-conventional anti-biofilm remedy. Using Staphylococcus aureus wound biofilms as a case study, we leverage a previously built in vitro 4-D wound microenvironment platform and a plant-based wound remedy. We find that EbbaBiolight 680 can be used to visualize S. aureus biofilms, likely detecting both bacterial cells and bacterial EPS components. Further, the optotracer can be used to evaluate and quantify the effects of the plant-based wound remedy on S. aureus biomass formation. However, in the 4-D wound microenvironment, EbbaBiolight 680 detected host cellular and matrix elements, which confounded the detection of biofilms. Taken together, this study opens the possibility of using optotracers as screening tools for the identification of novel anti-biofilm treatments and underscores the need for modifications for their use in host-relevant systems.