FIG 1.

Relative protein production of CMY-2 (blue), CTX-M-15 (green) and KPC-3 (purple) by isogenic strains of E. coli with or without exposure to ceftiofur. Average normalized densitometry values (3 independent replicates; ± SEM) for Flag-tagged recombinant CMY-2, CTX-M, and KPC-3 after 8, 10, 12, 14, or 16 h of culture with no antibiotic (A) or with 64 μg/mL of ceftiofur (B). Significant differences were found, based on two-way ANOVAs and Tukey multiple-comparison test: *, P < 0.05; **, P < 0.005; ***, P < 0.0005; ****, P < 0.0001.