Figure 6. Staphylococcal cell death affects biofilm development and pathogenesis.

(A) Representative CLSM micrographs of 1-day old biofilms of S. aureus UAMS-1 and isogenic mutants stained with SYTO9 (1.3 µM) and TOTO-3 (2 µM) to differentiate between live and dead cells. The images display top-down florescence projections of biofilms grown on glass slides (scale bar: 50 µm). Biofilm biomass (B), average thickness (C) and roughness coefficients (D) were calculated using the COMSTAT image analysis software, (statistical significance was assessed using one way ANOVA followed by Newman Kewl's multiple post-comparison test, n = 23; ** P<0.005, *** P<0.0005). (E) Experimental endocarditis was induced in rabbits by placement of a catheter into the left ventricle (see materials and methods). Bacteria (10⁵ cfu/ml) were inoculated 24 h after catheterization via the marginal ear vein. Animals were euthanized 48 h post infection, organs harvested and bacterial burdens determined by plating on tryptic soy agar plates (*, P<0.05, one way ANOVA with Dunnets multiple comparison test, n = 5/strain).