Fig 1.

Mutant selection window for quinolones of S. maltophilia strains expressing different amounts of the intrinsic resistance elements SmQnr and SmeDEF. The mutant selection windows for ofloxacin, nalidixic acid, norfloxacin, and ciprofloxacin were determined for the S. maltophilia strains D457 (wild type), MBS82 (SmQnr defective), MBS411 (SmeDEF defective), GGL199 (SmQnr and SmeDEF defective), and D457R (SmeDEF overproducer). Mutant selection windows are represented with gray boxes in which the upper part of each box stands for the MPC and the lower part of each box stands for the MIC. As shown, the size of the mutant selection window increases with the inactivation of intrinsic resistance determinants and decreases upon overexpression.