Fig 1.
Effect of specimen processing and kill curves for the antibiotics in the PANTA supplement.
(A.) There was 4.36+0.13 log10 CFU/mL difference in the bacterial burden between the cultures treated with NALC-NaOH versus no decontamination process. The limit of detection following the decontamination process was 1.47 log10 CFU/mL compare to the 0.42 log10 CFU/mL with no NALC-NaOH treatment. This loss in the bacterial burden means that specimens from children, where the disease is paucibacillary, could be erroneously flagged culture negative. Both (B) Time-to-positive and (C) solid agar methods showed that the decontamination steps significantly decrease the recovery of the M. tuberculosis. (D-H) Inhibitory Sigmoid Emax model derived kill curves with each of the five antibiotics in the PANTA supplement, where the model did not converge for trimethoprim and azilocillin. (Stock, pure culture without NALC-NaOH treatment; Decon, decontamination).
Fig 2.
Correlation between the time-to-positive from MGIT and the CFU/mL.
As shown by the R2, there was a good correlation between the M. tuberculosis bacterial burden recoded using the solid agar methods with the MGIT obtained time-to-positive for the (A) log phase growth, (B) semi-dormant bacilli, and (C) anaerobic cultures. However, the limit of detection was different between the metabolic populations.