Volume 18, Number 4—April 2012
Dispatch
Drug Susceptibility of Mycobacterium tuberculosis Beijing Genotype and Association with MDR TB
Jurriaan E.M. de Steenwinkel
, Marian T. ten Kate, Gerjo J. de Knegt, Kristin Kremer, Rob E. Aarnoutse, Martin J. Boeree, Henri A. Verbrugh, Dick van Soolingen, and Irma A.J.M. Bakker-Woudenberg
, Marian T. ten Kate, Gerjo J. de Knegt, Kristin Kremer, Rob E. Aarnoutse, Martin J. Boeree, Henri A. Verbrugh, Dick van Soolingen, and Irma A.J.M. Bakker-WoudenbergTable 2
Concentration- and time-dependent bactericidal effect of rifampin toward Mycobacterium tuberculosis genotypes in low- and high-density cultures*
| Day | Lowest RIF concentration resulting in killing of M. tuberculosis, mg/L |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Beijing-1585 genotype |
EAI-1627 genotype |
||||||||||
| >99% killing |
100% killing |
>99% killing |
100% killing |
||||||||
| Low† | High‡ | Low† | High‡ | Low§ | High¶ | Low§ | High¶ | ||||
| 1 | 8 | ND | 256 | ND | 8 | ND | 32 | ND | |||
| 3 | 1 | 0.008 | 64 | 1024 | 0.125 | 0.03 | 8 | 32 | |||
| 6 | 0.001 | 0.008 | 2 | 64 | 0.001 | 0.06 | 1 | 2 | |||
*Cultures were exposed to RIF at 2-fold increasing concentrations for 6 days at 37°C; at indicated time-points, subcultures were performed on solid media for counting. Low, low-density culture; high, high-density culture; ND, not determined.
†Density of 5.1 × 105 CFU/mL.
‡Density of 4.4 × 106 CFU/mL.
§Density of 6.8 × 105 CFU/mL.
¶Density of 3.0 × 106 CFU/mL.
