The effect of norA on resistance and cellular uptake for blasticidin S (BlaS), P10, and norfloxacin (NOR). (A) Disk diffusion assay showing zones of inhibition surrounding paper disks loaded with antibiotic overlaid on bacterial cultures of S. aureus TCH1516 WT (panel i), TCH1516 P10r-16 (ΔnorA) (panel ii), TCH1516 P10r-16::norA (norA complementation) exposed to blasticidin S (panel iii), TCH1516 WT (panel iv), TCH1516 P10r-16 (panel v), TCH1516 P10r-16::norA exposed to P10 (panel vi), TCH1516 WT (panel vii), TCH1516 P10r-16 (panel viii), and TCH1516 P10r-16::norA exposed to norfloxacin (panel ix). (B) E. coli NEB5α (left panel) and NEB5α::norA (right panel) exposed to blasticidin S (panel i), P10 (panel ii), and norfloxacin (panel iii). (C) Quantitation of the concentration of blasticidin, P10, and norfloxacin in cell lysates of E. coli NEB5α transformed with a control plasmid or the norA gene, exposed to each antibiotic; error bars represent standard deviations of results from three replicates.

Antimicrob Agents Chemother. 2017 Jun;61(6):e02635-16.