A. The number of bacteria is quantified via the log10 of the number of copies of gmk. Bacteria were pre-incubated overnight in fRPMI and incubated together with catheter fragments in fRPMI (filled diamonds) or in fRPMI-Fe25 (filled squares). The error bars represent the standard deviations. The line that links the data points helps to clarify the results at each time point measured. The time is given in hours in the x-axis. Fifteen samples from three independent cultures were assessed at each time point. B. Confocal laser scanning micrographs of sessile bacteria Bacteria were grown overnight in fRPMI and re-incubated together with polyurethane coated glass fragments in fRPMI-Fe25. Pictures were taken after 4 hrs (a) and after 24 hrs (b) of incubation. For each time point images show the xy-, xz- and yz-planes. The xy and orthogonal images of Staphylococcus epidermidis biofilms showed living cells (blue, syto9 stained) embedded in extracellular matrix (red, Wheat germ-agglutinin Alexa fluor® 633 stained) whereas the green areas (sytox orange strained) represent the dead bacteria. Experiments were performed in triplicate and biofilms were viewed at 100 × magnification.