Relationships between M. hominis PG21 and fluoroquinolone-resistant mutants IT1 to IIIT2F11 selected by stepwise exposure to trovafloxacin. The numbers outside the boxes indicate the trovafloxacin concentrations (in micrograms per milliliter) used in the selection steps. The superscripts +, °, and ∗ indicate the presence of mutations in GyrA, ParC, and ParE, respectively (Table 1).