Figure 7.

Cycle-threshold (Ct) differences between paired samples with same or different viscosities. The Mycobacterium tuberculosis Ct between concentrated sputum samples collected from a single patient is shown. Only tests with an internal control Ct less than 34 were included. Specimens were graded as “very viscous” (VV), “viscous” (V), or “not viscous/watery” (NV/W). Specimen pairs assigned the same viscosity category (both VV, both V, or both NV/W) are indicated in the left column. Specimen pairs with a one-grade difference (VV and V, or V and NV/W) are in the middle column. Specimen pairs with a two-grade difference (VV and NV/W) are in the right column. Each dot indicates a pair of specimens and dots are randomly distributed horizontally to reduce overlap. The mean change in M. tuberculosis Ct in each group is indicated by a solid black line. Gray boxes indicate ± one standard deviation.