TABLE 4.

Total bacterial loads and numbers of antibiotic-resistant mutant cells at the end of treatment for the different therapeutic groups of mice infected with PAO1 or PAOΔmutS

TreatmentStrainMedian total no. of cellsMedian total no. of mutant cells (frequency [no. of mutant cells/total no. of cells]) resistant toa:
CAZCIPTOB
PlaceboPAO11.5 × 1082.0 × 101 (1.3 × 10−7)<4 × 100<4 × 100
PAOΔmutS1.3 × 1085.0 × 103 (3.8 × 10−5)2.2 × 102 (1.2 × 10−6)5.6 × 102 (4.3 × 10−6)
CIPPAO12.8 × 101ND<4 × 100ND
PAOΔmutS1.8 × 104ND8.4 × 102 (4.7 × 10−2)ND
TOBPAO15.3 × 105NDND<4 × 100
PAOΔmutS6.8 × 105NDND2.0 × 101 (2.9 × 10−5)
CAZPAO11.2 × 106<4 × 100NDND
PAOΔmutS1.7 × 1051.4 × 103 (8.2 × 10−3)NDND
CIP-TOBPAO1<4 × 100ND<4 × 100<4 × 100
PAOΔmutS4 × 100ND<4 × 100<4 × 100
CAZ-TOBPAO11.4 × 104<4 × 100ND<4 × 100
PAOΔmutS4.5 × 104<4 × 100ND<4 × 100
CAZ-CIPPAO11.1 × 102<4 × 100<4 × 100ND
PAOΔmutS7.1 × 101<4 × 100<4 × 100ND
  • a Median total number of antibiotic-resistant mutant cells selected in plates containing a concentration of the indicated antibiotic that was fourfold higher than the MIC. Results in parentheses show the frequency of resistant mutant cells after treatment. ND, not determined.