FIG. 3.

Growth of ETEC strain H10407 in the presence of rifaximin (16 μg/ml) in water and an equimolar mixture of the synthetic bile acids cholic, deoxycholic, chenodeoxycholic, glycocholic, lithocholic, and taurocholic acids at pH 7.4. The total bile acid concentration was 4 mM. Cells were grown with rifaximin in the presence and absence of bile acids, and the absorbance at 600 nm was measured at 30-min intervals. Mann-Whitney two-tailed nonparametric t test analysis showed a statistically significant difference between treatments, as follows: no rifaximin plus no bile versus 16 μg/ml rifaximin, P = 0.026 (n = 4); no rifaximin plus no bile acids versus 16 μg/ml rifaximin plus bile acids, P = 0.002 (n = 4); and 16 μg/ml rifaximin versus 16 μg/ml rifaximin plus bile acids, P = 0.007 (n = 4). The error bars represent the standard deviations between four replicate experiments.