Figure 3.
Expression analysis of iron uptake genes and genes coding for β-lactamases in the AB5075 (A,C) and AMA40 (B,D) strains. qRT-PCR of pirA, piuA, bauA, bfnH, blaOXA-51-like, blaADC, blaOXA-23, blaNDM-1, and blaGES-11 expressed in human serum albumin (HSA), HSA Fe-free, HSA Fe-free supplemented with FeCl3, or HSA Fe-free supplemented with HSA. The data shown are the means ± SD of normalized relative quantities (NRQ) obtained from transcript levels calculated via the qBASE method. This method is a modification of the classic ΔΔCt method used to take multiple reference genes (in this work, rpoB and recA) and gene-specific amplification efficiencies into account. At least three independent samples were used, and four technical replicates were performed using each sample. The HSA condition was used as a reference. Statistical significance (p < 0.05) was determined by two-way ANOVA followed by Tukey’s multiple-comparison test, one asterisk: p < 0.05; two asterisks: p < 0.01; three asterisks: p < 0.001; and four asterisks: p < 0.0001.