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[Relationship between catalase activity, KatG gene and isoniazid-resistance in M. tuberculosis]
Objective:
To investigate the relationship between catalase activity, KatG gene, gene mutation and INH-resistance in M. tuberculosis.
Method:
Catalase activities in 58 M. tuberculosis isolates were tested, and KatG gene mutations were detected further by PCR-SSCP.
Result:
None of INH-sensitive isolates lacked KatG sequences and all expressed catalase. 8(25%) INH-resistant isolates did not express catalase and 3(10%) lacked KatG gene, most of which were strains of high levels of resistance (MIC > 50 micrograms/ml). 8 INH-resistant isolates were analyzed further by PCR-SSCP and all were found to have KatG gene mutation.
Conclusion:
These findings indicated that lacking of catalase activity and KatG gene deletion occurred mainly in those highly INH-resistant strains, gene mutation other than complete deletion of KatG gene may be the major mechanism of INH-resistance.