Role of the Dihydrofolate Reductase DfrA (Rv2763c) in Trimethoprim- Sulfamethoxazole (Co-Trimoxazole) Resistance in Mycobacterium tuberculosis

strains C (GenBank accession no.AAKR00000000) and CDC1551 (7), both of which belong tolineage 4, X-type (4). Given that strain CDC1551 is INH sus-ceptible (11), another mutation in strain 5297 must be respon-sible for drug resistance. In contrast, G285V has been pre-viously identified as the sole mutation in