Comparative measurement of transcription of the folate synthesis‐related genes in APEC strains with SXT. Comparative measurement of transcription (cDNA abundance) of luxS, metE, and metH in APEC 17, APEC 19, APEC 29, and APEC 40. Relative transcript levels of luxS, metE, and metH were tested by real‐time reverse transcription‐PCR in APEC 17, APEC 19, APEC 29, APEC 40, and APEC 17, APEC 19, APEC 29, APEC 40 cultured with 39 μmol/L AI‐2 in the presence of SXT: (a) APEC 17 with 50/950 ng/ml, (b) APEC 19 with 20/380 ng/ml, (c) APEC 29 with 20/380 ng/ml, and (d) APEC 40 with 20/380 ng/ml. Error bars indicate standard deviations. The results represent a mean of three independent experiments; **p < .01, indicating a difference between SXT and SXT + AI‐2