Evaluation of katG codon 315 mutations among isoniazid sensitive and resistant mycobacterium tuberculosis isolates from Thailand.

Nine isoniazid (INH)-susceptible and 11 INH-resistant Mycobacterium tuberculosis clinical isolates were analyzed for katG codon 315 mutations by polymerase chain reaction (PCR) assay using primers MYC-32 and MYC-33, followed by restriction fragment length polymorphism. After AciI digestion of PCR products, all 9 INH-susceptible isolates and 5 out of 11 (45%) INH-resistant isolates showed 0.12 kb band, which was previously reported to indicate wild type, whereas, 6 of 11 (55%) INH-resistant isolates lacked this band.