[Study on the mutations of ahpC genes in M. tuberculosis isoniazid-resistant isolates].

OBJECTIVE

To investigate the mutations of ahpC genes in M. tuberculosis isoniazid-resistant isolates, and to study the correlation between ahpC alterations and isoniazid resistance.

METHOD: Analyzing the ahpC coding sequences and ahpC promoters in 62 M. tuberculosis clinical isolates with PCR-SSCP method. M. tuberculosis strain H37RV was used as control.

RESULT: The ahpC coding sequences showed normal SSCP profiles in 62 clinical isolates. AhpC promoter mutations were identified in 5 of 12 high isoniazid-resistant strains, and were not altered in 18 low isoniazid-resistant and 32 drug-sensitive isolates.

CONCLUSION

The mutation of ahpC coding gene was not correlated with isoniazid-resistant M. tuberculosis isolates. AhpC promoter mutation was a compensatory change in katG-defective and catalase-negative isolates, may be used as a indirect marker for high resistance to isoniazid.