Comparison of DNA sequencing, PCR-SSCP Pha-B assays with indirect sensitivity testing for detection of rifampicin resistance in Mycobacterium tuberculosis.

Mani, C.; Selvakumar, N.; Kumar, V.; Narayanan, S.; Narayanan, P.R.

International Journal of Tuberculosis and Lung Disease; 2003; 7; 652-659.

Setting : Tuberculosis Research Centre, Chennai.

Objective : To rapidly identify multidrug-resistant Mycobacterium tuberculosis using phenotypic and genotypic methods.

Design : Two genotypic assays, DNA sequencing and polymerase chain reaction single strand conformation polymorphism (PCR-SSCP), and one phenotypic assay, phage amplified biological assay (PhaB) were standardized in-house and performed on coded 101 rifampicin-resistant and 100 rifampicin-sensitive M. tuberculosis clinical isolates for the identification of rifampicin resistance.

Results & Conclusion : The results obtained using the three assays were compared with those from the conventional indirect sensitive test. The sensitivities and specificities of DNA sequencing, PCR-SSCP and PhaB were 97% and 100%, 76% and 100%, and 97% and 84%, respectively. DNA sequencing was found to be more sensitive and specific than the other tests.

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