Table 1.
Comparison of phenotypic and molecular DST results
| Molecular method and result | No. of strainsa (%) |
Assessment characteristic (%)b |
||||
|---|---|---|---|---|---|---|
| Resistant to FQ (n = 32) | Sensitive to FQ (n = 19) | Sensitivity | Specificity | PPV | NPV | |
| Sequencing | ||||||
| Resistant | 26 (81.3) | 1 (5.3) | 89.6 | 94.7 | 96.3 | 85.7 |
| Sensitive | 3 (9.4) | 18 (94.7) | ||||
| Unreadable | 0 | 0 | ||||
| Mixed | 3 (9.4) | 0 | ||||
| Pyrosequencing | ||||||
| Resistant | 25 (78.1) | 0 | 86.2 | 100 | 100 | 82.6 |
| Sensitive | 4 (12.5) | 19 (100.0) | ||||
| Unreadable | 0 | 0 | ||||
| Mixed | 3 (9.4) | 0 | ||||
| MTBDRsl | ||||||
| Resistant | 25 (78.1) | 0 | 86.2 | 100 | 100 | 82.6 |
| Sensitive | 4 (12.5) | 19 (100.0) | ||||
| Unreadable | 3 (9.4) | 0 | ||||
| Mixed | 0 | |||||
a
Strains harboring mutations in QRDRs were considered resistant to FQ.
b
Compared to the gold standard (phenotypic) for readable results only. Resistance results for mixed cultures are excluded. PPV, positive predictive value; NPV, negative predictive value.