TABLE 1.
Polymyxin B MIC distributions for P. aeruginosa, A. baumannii and K. pneumoniae. a
| Strain (n) | MIC50 (mg/L) | MIC90 (mg/L) | MIC (mg/L) distribution (%) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.125 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | >32 | |||
| Pa (517) | 1 | 1 | 0.39 | 0.58 | 7.74 | 87.8 | 1.93 | 1.35 | 0 | 0 | 0 | 0.19 |
| Ab (262) | 0.5 | 0.5 | 0 | 1.53 | 93.1 | 4.96 | 0 | 0 | 0 | 0 | 0 | 0.38 |
| Kp (652) | 0.5 | 0.5 | 0.46 | 26.1 | 65.5 | 4.91 | 1.84 | 0.15 | 0.61 | 0 | 0 | 0 |
a
Resistance to meropenem (i.e., MIC ≥8 mg/L for P. aeruginosa and A. baumannii, MIC ≥4 mg/L for K. pneumoniae) was detected in 25.9% of P. aeruginosa isolates, 85.5% of A. baumannii isolates, and 37.0% of K. pneumoniae isolates.MIC50, the MIC value at which ≥50% of isolates are inhibited; MIC90, the MIC value at which ≥90% of isolates are inhibited.