TABLE 5.
Medium lot and interlaboratory comparisons for nafithromycin MIC testing results for E. faecalis ATCC 29212a
| MIC (μg/ml) | No. of occurrences for medium lot: |
No. of occurrences for laboratory: |
Total no. of occurrences | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | A | B | C | D | E | F | G | H | I | ||
| 0.008 | |||||||||||||
| 0.016 | |||||||||||||
| 0.03 | 85 | 82 | 11 | 22 | 20 | 14 | 25 | 19 | 18 | 19 | 21 | 20 | 178 |
| 0.06 | 5 | 8 | 75 | 8 | 10 | 12 | 5 | 11 | 12 | 11 | 9 | 10 | 88 |
| 0.12 | 4 | 4 | 4 | ||||||||||
| 0.25 | |||||||||||||
| Total | 90 | 90 | 90 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 270 |
| Median | 0.03 | 0.03 | 0.06 | 0.03 | 0.03 | 0.06 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 |
| Mode | 0.03 | 0.03 | 0.06 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 |
| Geometric mean | 0.03 | 0.03 | 0.06 | 0.04 | 0.04 | 0.05 | 0.03 | 0.04 | 0.04 | 0.04 | 0.04 | 0.04 | 0.04 |
| Range | 2 | 2 | 3 | 2 | 2 | 3 | 2 | 2 | 2 | 2 | 2 | 2 | |
a
The all-laboratory-medians approach of Gavan et al. (10) was used to calculate the proposed QC range of 0.016 to 0.06 μg/ml (all-laboratory median, 0.03 μg/ml; median of ranges, 2 μg/ml; one-half median of ranges rounded up, 1 μg/ml); 98.5% (266/270) of all qualified results were within the proposed QC range of 0.016 to 0.06 μg/ml. Due to the significant shoulder at 0.06 μg/ml, it was recommended that the range be expanded to include 0.12 μg/ml (0.016 to 0.12 μg/ml) (in boldface type), which included 100% (270/270) of all qualified results.