Detection of isoniazid and rifampin resistance of Mycobacteriumtuberculosis by a multiplex allele-specific polymerase chain reaction (PCR) assay.

Background: The use of molecular techniques is a major improvement for the rapid routine detection and control of multidrug-resistant tuberculosis (MDR-TB).

Materials: In this study, the multiplex allele-specific polymerase chain reaction (MAS-PCR) was developed to simultaneously detect the most frequent mutations associated with isoniazid (INH) and rifampin (RIF) resistance in a single assay.

Results: The assay was tested with 53 clinical isolates. Among them, 27 were MDR strains, 17 were mono-resistant to INH, one was mono-resistant to RIF, and eight were susceptible. The MAS-PCR assay showed a specificity of 100% in detecting drug resistance. An equivalent sensitivity of 92.6% in detecting MDR and RIF-resistance was found. The sensitivity for the detection of INH-resistance was 88.6%.

Conclusions: The MAS-PCR assay was a simple and rapid method for detecting the INH and RIF-resistance in Mycobacterium tuberculosis (MT) clinical strains. It is also easy to perform and to interpret. The assay is inexpensive and a less-demanding technique.