S1: Visualizing antimicrobial action against biofilms

Because biofilms are complex communities of microorganisms embedded within a matrix of extracellular polymer, processes which occur within them can be difficult to understand and predict.  While it is well known that biofilms exhibit a much higher tolerance to antimicrobial agents than do planktonic cells, the mechanisms of this tolerance are often not well understood.  Biofilm control measures ideally would both kill biofilm cells and remove the dead cells and extracellular matrix from the surface.  In practice, however, many chemical agents are not effective at both killing and removal.  Understanding the reaction of biofilms to chemical agents and simple physical stresses (such as shear stress) can aid the design of new chemistries and assist practitioners in choosing the right treatment regime. Recent advances in microscopy, including image collection and staining techniques, provide a better understanding of how biofilms react to physical and chemical stresses by illustrating the progression of cell death and/or biofilm erosion with time.  This presentation will highlight several of these microscopy-based imaging techniques to illustrate the effects of antimicrobial agents, flow regime changes, and extracellular matrix-specific agents on intact biofilms.  The effects of specific chemistries and staining dyes will be presented, and implications for anti-biofilm treatment strategies will be discussed.