TABLE 2.

Changes in P. aeruginosa colony counts in initial-inoculum, single-dose colistin experiments

Time (h)Change in colony count (log10 CFU/ml) with colistin at indicated Cmax (mg/liter) and/or indicated druga
6, +CTZb18, +CTZb6, +CTZc18, +CTZcCTZ aloneb6, +CIPb,d18, +CIPb,d
1−2.30−2.96≥−3.52−3.390.08−2.99−2.76
2≥−3.52≥−3.52≥−3.52≥−3.52−0.01≥−3.52≥−3.52
3≥−3.52≥−3.52≥−3.52≥−3.52−0.63≥−3.52≥−3.52
4≥−3.52≥−3.52≥−3.52≥−3.52−1.60−3.41≥−3.52
5.5≥−3.52≥−3.52≥−3.52≥−3.52−1.94−2.37≥−3.52
7≥−3.52≥−3.52≥−3.52≥−3.52−2.10−1.90≥−3.52
12≥−3.52≥−3.52≥−3.52≥−3.52−1.92−1.08−1.86
24−2.51−2.75−2.77−2.84−1.701.780.08
26−2.96≥−3.52−3.43≥−3.52
28−2.90≥−3.52−3.45≥−3.52
30−3.17≥−3.52−3.03≥−3.52
48−2.09−2.79−2.09−2.25
  • a Colistin Cmax was achieved at time zero only. Ceftazidime (CTZ) concentration was maintained as a constant infusion. The time of sampling varied slightly in certain experiments between 5.5 and 30 h, but the variation was within 15 to 60 min of the stated sampling times. CTZ, ceftazidime.

  • b P. aeruginosa M29899-1.

  • c P. aeruginosa H23259-1.

  • d Ciprofloxacin (CIP) was given to achieve a Cmax of 5 mg/liter at 0 and 12 h.