Article Figures & Data
Figures
- FIG. 1.
LVX MIC results for susceptible and resistant clinical isolates of M. tuberculosis. LVX MIC results for BACTEC 460, BACTEC MGIT 960, and AP methods are shown for 32 pan-susceptible clinical isolates of M. tuberculosis and 14 M. tuberculosis isolates that either were clinically resistant to LVX or had known DNA gyrase resistance mutations.
Tables
- TABLE 1.
Drug stability study of BACTECa
LVX concn (μg/ml) Treatment Reading no. 1 2 3 4 5 Avg 2.0 Fresh 39 44 43 41 44 42.2 4°C 41 41 45 35 46 41.6 37°C 40 37 42 40 41 40.0 1.0 Fresh 90 81 75 78 103 85.4 4°C 70 61 86 70 94 76.2 37°C 131 63 46 57 58 71.0 ↵ a Results of the drug stability studies in the BACTEC system for LVX at two concentrations in freshly prepared drug-containing medium, medium stored at 4°C for 14 days, and medium stored at 37°C for 14 days inoculated with M. tuberculosis strain H37Rv. GI readings in units at the time the drug-free control reached a GI of ≥30 (5 days) for the various treatments are shown.
- TABLE 2.
Drug stability study with BACTEC MGIT 960 systema
LVX concn (μg/ml) Treatment No. of days to positivity for reading no. 1 2 3 4 5 Avg 0.5 Fresh 16.0 19.8 18.2 17.2 21.1 18.5 4°C 24.5 23.4 16.2 25.9 23.5 22.7 37°C 24.5 21.1 16.8 27.9 18.8 21.8 0.25 Fresh 5.3 5.4 5.8 4.6 6.1 5.4 4°C 6.0 5.3 5.5 6.1 4.3 5.4 37°C 4.7 4.9 5.2 4.8 4.8 4.9 ↵ a Results of the drug stability studies in the BACTEC MGIT 960 system for LVX at two subinhibitory concentrations in freshly prepared drug-containing medium, medium stored at 4°C for 14 days, and medium stored at 37°C for 14 days inoculated with M. tuberculosis strain H37Rv. The number of days to positivity indicates the number of days to achieve detectable growth with the BACTEC MGIT 960 instrument. A control with no drug was also tested and became positive in 3.3 to 3.5 days.
- TABLE 3.
Results of critical concentration testing of three methodsa
Method LVX test concn (μg/ml) No. of isolates with susceptible results/No. susceptible No. of isolates with resistant results/No. resistant BACTEC 460 2 8/9b 14/14 BACTEC MGIT 960 2 9/9 14/14 AP 1 23/24c 13/14d ↵ a Results of LVX critical concentration testing for the BACTEC 460, BACTEC MGIT 960 and AP methods. The critical test concentrations of LVX were chosen for each method based on results of testing clinical isolates of M. tuberculosis with known LVX susceptibilities. The selected critical test concentrations were then tested against a subset of LVX-susceptible M. tuberculosis isolates as well as isolates that were either clinically resistant to LVX or had known gyrA mutations associated with quinolone resistance.
↵ b One isolate failed to grow in 12B medium.
↵ c One 7H10 plate was unevaluable due to contamination.
↵ d One isolate tested borderline resistant (1 to 10%). One isolate failed to grow on 7H10 medium.
