FIG 1 .

Endogenous heme biosynthesis is required for full S. aureus pathogenesis. (A) The growth of the wild type (WT; circles) or an hemA mutant (open squares) of S. aureus was monitored over time by optical density at 600 nm. The final concentration of aminolevulinic acid (ALA) and heme added to the growth medium was 75 µg ml⁻¹ (gray squares) and 2 µM (gray diamonds), respectively. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (B) Female BALB/c mice were systemically infected with 10⁷ CFU of the wild type (WT; circles) or an hemA mutant (squares) of S. aureus, and bacterial burdens were determined 96 h postinfection. The dotted line represents the limit of detection. Error bars represent one standard deviation from the mean. The mean is represented by a horizontal bar. *, P < 0.0001, via an unpaired Student t test. Gray symbols represent organs where no bacteria were recovered. None of the mice infected with the hemA mutant had recoverable CFU in the heart. Five mice had recoverable CFU in the kidneys and the liver when infected with the hemA mutant.