FIG 5.

Real time-PCR-based quantification of transcript levels of different stx alleles in EHEC O157:H7 isolate EDL933 and urine isolates UR5703/202, UR5779/201, and UR131. Data represent the normalized fold expression levels of the different stx alleles upon growth in pooled human urine, LB, RPMI 1640, or SCEM after 2 h, 4 h, and 12 h of growth. Error bars show the standard errors of the means of three independent experiments and technical replicates. The individual stx transcript levels were normalized to the transcript level of the housekeeping gene gapA and compared with the level at the starting point (2 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001.