A: standardised suspensions of S. aureus SH1000 and SRC005 cultured in iron-depleted or iron-replenished CL medium (CL, CLFeCl3) were assayed for the ability of cell surface–exposed IsdA to enhance cell clumping in the presence of purified human fibrinogen. Clumping titers were recorded as the lowest fibrinogen concentration at which clumping remained visible. The box and whisker plots show the median line, the 75th and 25th percentiles (box) and the data range (whisker). Outlier values (circle symbols) fall 1.5-3 box lengths from the 75th/25th percentile, and extreme values (square symbols) fall >3 box lengths from the 75th/25th percentile. B: example images of bacterial clumping in decreasing fibrinogen concentrations and under control conditions.
