Fig 1.

Biofilm formation and gene expression. (A) Biofilm formation by clinical isolates (12 from blood and 13 from ear) after 24 h of growth at either pH 7.4 or 6.8, with or without 100 μM Fe(III), determined by viable count. Data are the means ± standard deviations for three independent experiments (*, P < 0.05; **, P < 0.01; and ***, P < 0.001; 2-tailed Student's t test). (B and C) Expression of luxS (B) and piuA (C) relative to 16S rRNA in the indicated clinical isolates grown either at pH 7.4 or 6.8, with or without addition of 100 μM Fe(III). Data are the means ± standard deviations for three independent experiments (*, P < 0.05; **, P < 0.01; and ***, P < 0.001; 2-tailed Student's t test).