Table 2.

Log changes in CFU/ml^a

^aLog changes in CFU/ml at 6, 24, 48, 72, and 96 h at an inoculum of 10⁶ or 10⁸ CFU/ml with colistin (Col) and/or doripenem (Dor) against P. aeruginosa. The gray background indicates activity (a reduction of ≥1-log₁₀ CFU/ml below the initial inoculum); the green background indicates synergy (a ≥2-log₁₀ decrease in the number of CFU per milliliter with the combination compared to its most active component); the red background indicates additivity (a 1.0- to <2-log₁₀ decrease in the number of CFU per milliliter with the combination compared to its most active component). ††, colistin-heteroresistant reference strain. Heteroresistance to colistin was defined as the ability of subpopulations of a strain to grow in the presence of >2 mg/liter although the colistin MIC for the strain was ≤2 mg/liter. ‡‡, nonmucoid MDR colistin-resistant clinical isolate (colistin monotherapy was performed with 5 mg/liter only).