FIG. 1.

Consensus nucleotide mutations present in the topoisomerase IV and gyrase genes of 12 fluoroquinolone-resistant and 4 fluoroquinolone-susceptible strains. Silent mutations (not boxed) are indicated with thin arrows. Open boxes, mutations that cause amino acid substitutions in both fluoroquinolone-resistant and fluoroquinolone-susceptible strains; solid boxes, mutations that cause amino acid substitutions at the same positions as those described for fluoroquinolone-resistant S. aureus; shaded boxes, additional mutations that cause amino acid substitutions in fluoroquinolone-resistant S. pseudintermedius.