Table 1.
Performance of qPCR phage, MTT, and Sequencing compared to standard MGIT PZA susceptibility results.
| Test method | Standard MGIT (n)
|
Accuracy (%) | Sensitivity (%) | Specificity (%) | ||
|---|---|---|---|---|---|---|
| Rc | Sd | |||||
| Phage assaya | R | 29 | 5 | 89 | 94 | 85 |
| S | 2 | 28 | ||||
| MTT assayb | R | 29 | 8 | 83 | 88 | 78 |
| S | 4 | 28 | ||||
| Sequencing | Mt | 31e | 4 | 90 | 91 | 89 |
| Wt | 3 | 33 | ||||
a
7/71 did not “grow”,
b
2/71 did not “grow”.
c,d
18 isolates were found to have some discrepancy between the 3 methods and all were retested by MGIT whereby 6/13 originally resistant by MGIT were then deemed susceptible and 1/5 originally susceptible by MGIT was then deemed resistant. We used these as the final MGIT result.
e
4/31 had mixed mutant/wild-type pncA traces by sequencing and we called them mutant. Mt, mutant type. Wt, wild type.