Acetylation of Isoniazid Is a Novel Mechanism of Isoniazid Resistance in Mycobacterium tuberculosis

Isoniazid (INH), one of the first-line drugs used for the treatment of tuberculosis, is a prodrug which is activated by the intracellular KatG enzyme of Mycobacterium tuberculosis . The activated drug hinders cell wall biosynthesis by inhibiting the InhA protein. INH-resistant strains of M. tuberculosis usually have mutations in katG , inhA , ahpC , kasA , and ndh genes. However, INH-resistant strains which do not have mutations in any of these genes are reported, suggesting that these strains may adopt some other mechanism to become resistant to INH.