Table 1.
Accuracy (% relative error) and precision (% coefficient of variation) of the assay, grouped by sample matrix and polymyxin B base concentration. Overnight bacterial cultures contained a high bacterial concentration (~108 CFU/mL).
| Sample Type | Sterile |
A. baumannii ATCC 19606 |
P. aeruginosa ATCC 27853 |
K. pneumoniae ATCC 13883 |
|---|---|---|---|---|
| Number of samples at each concentration | 24a | 6b | 6b | 6b |
| % Relative error (% Coefficient of variation) | ||||
| Polymyxin B base concentration | Cation-adjusted Mueller-Hinton Broth | |||
| 0.103 mg/L | 1.89 (9.61) | 9.44 (8.96) | 4.99 (9.39) | −0.914 (8.41) |
| 0.248 mg/L | −7.86 (6.16) | −8.66 (3.17) | 1.45 (6.70) | −4.58 (4.11) |
| 2.48 mg/L | 0.186 (3.85) | −2.15 (2.14) | 1.55 (5.10) | 1.60 (2.46) |
| 4.95 mg/L | 3.06 (2.55) | 6.13 (1.02) | 0.639 (3.97) | 3.25 (6.53) |
| 6.60 mg/L | 5.67 (6.41) | 7.87 (1.92) | 1.67 (1.91) | 5.53 (1.04) |
| Tryptone Soya Broth | ||||
| 0.248 mg/L | −4.68 (10.5) | −17.50 (2.78) | −9.40 (5.56) | −6.24 (3.60) |
| 2.48 mg/L | 2.86 (7.57) | −0.95 (6.54) | 6.49 (8.98) | 5.41 (6.28) |
| 4.95 mg/L | −1.05 (6.72) | −5.29 (3.34) | 3.61 (6.56) | 5.16 (3.21) |
| 6.60 mg/L | −0.586 (6.31) | −6.51 (6.11) | 1.12 (3.58) | 4.27 (2.46) |
a
Pooled over 4 separate assay days, with 6 replicates assayed per day (Inter-day precision represented)
b
All 6 replicates completed on the same day (Intra-day precision represented)