TABLE 2.

In vitro mutation frequencies and mutation rates for strains PAO1 and PAOΔmutSa

Antibiotic (concn[s] [μg/ml])Mutation frequency (no. of mutants/cell) for strain:Mutation rate (no. of mutants/cell/division) for strain:
PAO1PAOΔmutSPAO1PAOΔmutS
CIP (0.5)3.5 × 10−71.3 × 10−53.8 × 10−89.6 × 10−7
CIP (2)<5.0 × 10−117.4 × 10−11≤1 × 10−114.6 × 10−11
TOB (4)3.0 × 10−72.3 × 10−53.3 × 10−81.7 × 10−6
TOB (16)<5.0 × 10−112.4 × 10−7≤1 × 10−112.6 × 10−8
CAZ (4)2.9 × 10−77.3 × 10−43.0 × 10−84.1 × 10−5
CAZ (16)2.7 × 10−71.0 × 10−42.9 × 10−86.7 × 10−6
CIP-TOB (0.5, 4)<5.0 × 10−111.1 × 10−10≤1 × 10−115.8 × 10−11
CAZ-TOB (16, 4)<5.0 × 10−116.3 × 10−9≤1 × 10−111.2 × 10−9
CAZ-CIP (16, 0.5)<5.0 × 10−112.0 × 10−9≤1 × 10−115.0 × 10−10
  • a Mutation frequencies and rates after CIP, TOB, and CIP-TOB administration obtained in a previous study (23) are included for comparison.