A novel genotypic test for rapid detection of multidrug-resistant Mycobacterium tuberculosis isolates by a multiplex probe array.

Aims: To develop and evaluate a novel genotypic test for rapid detection of rifampicin and isoniazid resistance of multidrug-resistant (MDR) Mycobacterium tuberculosis isolates by a multiplex probe array. Methods and Results: A multiplex probe array was designed for genotypic test to simultaneously screen the mutations of rpoB, katG, inhA and ahpC genes, associated with rifampin and isoniazid resistance in M. tuberculosis, with a probe detecting one of the recently confirmed genetic markers of isoniazid resistance ahpC-6 and -9 locus added. By using the genotypic test developed, 52 MDR isolates were identified, among which 46 isolates had mutations in rpoB (88·5%) and 45 at codon 315 of katG, regulatory region of inhA and oxyR- ahpC intergenic region (86·5%), whereas all 35 susceptible isolates identified showed a wild-type hybridization pattern. The sensitivity and specificity were 88·5% and 100% for rifampicin resistance, and 86·5% and 100% for isoniazid resistance, respectively. Conclusion: A rapid and simultaneous detection of rifampicin and isoniazid resistance caused by the mutations of rpoB, katG, inhA and ahpC genes in M. tuberculosis isolates could be achieved by a multiplex probe array developed. Significance and Impact of the Study: This genotypic test protocol has the potential to be developed on clinical application for the rapid detection of drug resistant M. tuberculosis isolates before an efficient chemotherapy is initiated. [ABSTRACT FROM AUTHOR]