In situ tracking of microbeads for the detection of biofilm formation.

In this study, we utilize the free motion of beads incorporated in bacterial suspension to investigate the behavior of the medium surrounding the beads during biofilm formation. The use of imaging techniques such as digital image correlation enables tracking of the movement of beads, which serve as markers in the processed images. This method is applied to detect and characterize biofilm formation. The main originality of this study lies in characterizing the evolution of the typology of bead movements during biofilm formation. The aim is to identify bead behaviors that represent the start of biofilm formation. By observing inert bead movements introduced into the bacterial environment, changes in trajectory typologies are detected and appear to be related to sessile bacterial activity, bacterial hindrance, and adhesion or formation of extracellular material. We use our approach to discriminate between the presence or absence of antibiotics mixed with bacteria and to assess their effectiveness. The results highlight the potential of our approach as nondestructive tracking of biofilm dynamics over time based on optical microscope images.