Table 1. Frequency and patterns of resistance conferring mutations in M. tuberculosis isolates that were resistant to rifampicin (n = 45) and isoniazid (n = 50).
| Drug | Locus | Mutationa | Frequency (No. of Isolates) |
Relative Frequencyb (%) |
|---|---|---|---|---|
| Ser531Leu | 18 | 18/45 (40) | ||
| His526Xc | 12 | 12/45 (27) | ||
| RIFAMPICIN | rpoB | Asp516Tyr | 04 | 4/45 (9) |
| Any of Ser531Leu, His526Tyr or Asp516Tyr | 34 | 34/45 (76) | ||
| Leu511Pro | 02 | 2/45 (4) | ||
| Glu513Lys | 01 | 1/45 (2) | ||
| Glu588Gly | 01 | 1/45 (2) | ||
| No mutation in rpoB | 08 | 8/45 (18) | ||
| Ser315Thr | 38 | 38/50 (76) | ||
| katG | Any of Ser315Thr, C(-15)T or T(-8)C | 40 | 40 /50 (80) | |
| Ser315Thr+any mutation in inhA gene promoter | 06 | 06/50 (12) | ||
| No mutation in katG | 12 | 12/50 (24) | ||
| Any mutation in inhA gene promoter | 08 | 08/50 (16) | ||
| Any mutation in inhA gene promoter but no mutation in katG (Ser315Thr) | 02 [with C(-8)A or C(-15)T] | 02/50 (4) | ||
| C(-15)T + Ser315Thr | 04 | 04/50 (8) | ||
| C(-15)T | 04 | 4/50 (8) | ||
| ISONIAZID | T(-8)C | 02 | 2/50 (4) | |
| inhA gene promoter | A(-7)C | 1 (occurred in isolate with G(-116)A) | 1/50 (2) | |
| G(-116)A | 01 | 1/50 (2) | ||
| A(-255)C | 01 | 1/50 (2) | ||
| C(-305)T | 1 (occurred in isolate with C(-15)T) | 1/50 (2) | ||
| No mutation in inhA | 42 | 42/50 (84) | ||
| No mutation both in inhA & katG | 10 | 10/50 (20) |
aWe used the Escherichia coli codon numbering for rpoB mutations
bCompared with the total number of isolates resistant to drug of interest see Campbell et al (2011) [6]
cMutations affecting the 526 codon included His526Asp (6 isolates), His526Tyr (3 isolates), His526Arg (1 isolate), His526Gly (1 isolate), and His526Leu (1 isolate).