Schematic illustration of the combined 16S-RD assay. A: For the 16S assay (tube 1), TaqMan (T) signals show the presence or absence of MTBC-specific 16S rDNA sequence, whereas the SYBR Green (S) signals indicate the presence or absence of Mycobacterium genus-specific 16S rDNA sequence. B: For the RD assay (tube 2), T signals show the presence or absence of RD750, whereas the S signals act as further confirmation of MTBC-specific sequence and a positive assay control when the T signal is negative. T+ S− signals would be anomalous in both assays, indicating amplicons that do not interact with SYBR Green; no results were obtained in this category.