Staphylococcus Epidermidis Biofilm Microstructure Characterized by Confocal Laser Scanning Microscopy

Biofilms are colonies of microorganisms encapsulated in the protective layer of a polysaccharide matrix. Bacterial biofilms commonly form on the surface of intravenous medical devices and are hypothesized to fracture or erode from the device surface and proliferate throughout the blood stream, thereby potentially causing systemic infection.  Every year ~1% of Americans have blood stream infections, of these patients 20-30% die¹.  Staphylococcus epidermidis is frequently involved in nosocomial (hospital-related) bacterial biofilm infections associated with contaminated medical devices.  This work will present measurements of the impact of fluid flow on S. epidermidis biofilm formation by analyzing the bacterial microstructure in the biofilm with confocal laser scanning microscopy (CLSM). Of particular interest are the shear rates of the experiments, which were set in ranges that approximate physiological conditions.  3D image volumes acquired by the CLSM were analyzed with image processing tools to extract material properties of the structures formed such as the mean separation between bacterial cells in the biofilm.  This microscopic structural information complements the more typical morphological studies of biofilm structure which do not resolve individual cells.  The intercellular structure probed here is of interest to investigate fundamental questions about the life cycle of biofilms including their growth, fracture and erosion.  The evolution of these properties with time, as well as their correlation with flow conditions is discussed.

¹http://www.cdc.gov/ncidod/eid/vol7no2/wenzel.ht