Reverse dot blot hybridization for detection of gyrA mutation for rapid diagnosis of Mycobacterium tuberculosis resistant to fluoroquinolones

Rapid detection and timely treatment are of great significance to reduce Mycobacterium tuberculosis (M. tuberculosis) transmission, especially in cases suffering from the infection of multidrug-resistant (MDR) or extensively drug-resistant (XDR) M. tuberculosis. Here we have developed a reverse dot blot hybridization (RDBH) technique for rapid diagnosis of M. tuberculosis resistance to fluoroquinolones (FQ). One wild-type and seven mutant oligonucleotide probes were designed to detect the gyrA gene common mutations conferring to FQ resistance. A total of 160 clinical M. tuberculosis isolates including 83 FQ-resistant and 77 FQ-sensitive strains were analyzed in this study. Compared with the results of culture-based phenotypic drug susceptibility test (DST), the overall sensitivity, specificity and accuracy of this RDBH assay were 71.1% (59/83), 100% (77/77) and 85.0% (136/160), while compared with direct DNA sequencing method, the sensitivity, specificity and accuracy of the RDBH were 93.7% (59/63), 100% (97/97) and 97.5% (156/160), respectively. Therefore, the newly-established RDBH assay is rapid, simple and efficient method to detect fluoroquinolones resistance of M. tuberculosis and can hold the promise for screening FQ-resistance in the clinical samples from the patients with tuberculosis.