On the contrary, the occurrence of inhA-RR −15 C/T mutation alone was significantly higher in MDR-TB strains resistant to two drugs versus isolates resistant to three drugs (7 of 27 versus 2 of 32, P = 0.036) as well as versus isolates resistant to all four drugs (7 of 27 versus 2 of 34, P = 0.028). This evidence concerns the gene INHA and tuberculosis.