Figure 2.

Direct MTBDRplus testing of sputum is successful in almost all smear-positives and most smear-negatives, however, it fails to generate a susceptibility result in a significant minority of smear-negatives (one in five), indicating that a failure to detect TB is the primary cause of drug-resistance being missed (i.e., non-actionable results). Furthermore, a significant minority of Xpert rifampicin-resistant patients do not have MDR per MTBDRplus, suggesting a continued role for isoniazid DST. Importantly, in patients with actionable MTBDRplus results, sensitivity and specificity for resistance did not differ by smear status. Resistance classifications on bottom two rows of boxes are per direct MTBDRplus

Of the 951 Xpert rifampicin-resistant patients only 849 were confirmed culture-positive.

*Indirect smear-positive MTBDRplus results: MDR (n=7), Rif-mono (n=0), INH-mono (n=1), fully-susceptible (n=3), and non-actionable (n=0).

**Indirect smear-negative MTBDRplus results: MDR (n=69), Rif-mono (n=0), INH-mono (n=3), fully-susceptible (n=20), and non-actionable (n=0).

Abbreviations: RIF-rifampicin, INH-isoniazid, mono-mono-resistant, MDR-multi–drug resistant, TUB-TUB-band, n-number, Xpert-Xpert MTB/RIF.