TABLE 2

FIC indices from checkerboard titration synergy testing

StrainRange of calculated FIC indices for drug combinationa (interpretation)
CIP-CSTCIP-TOBCIP-MEMCST-TOBCST-MEMTOB-MEM
PAO10.56–1 (additivity)0.75–1 (additivity)0.63–1 (additivity)0.63–1 (additivity)0.26–1 (synergy/additivity)0.56–1 (additivity)
PA500.56–1 (additivity)1 (additivity)1 (additivity)0.26–1 (synergy/additivity)0.56–1 (additivity)0.63–1 (additivity)
PA2911 (additivity)0.53–1 (additivity)0.63–1 (additivity)0.75–1 (additivity)1 (additivity)0.75–1 (additivity)
  • a CIP, ciprofloxacin; CST, colistin; MEM, meropenem; TOB, tobramycin. FICs were determined by checkerboard titration; the values correspond the minimal and maximal FIC values calculated for the different combinations of concentrations tested.