Fast identification of rifampicin-and isoniazid resistance of M. Tuberculosis strains by the "TB-biochip" test system

A total 988 specimens were obtained from patients with pulmonary tuberculosis, which were all diagnosed according to clinical and X-ray and bacteriological studies. 940 patients were newly diagnosed without any history of treatment; 48 patients with a history of treatment one course. Mutations of rpoB, katG, inhA and ahpC gene associated with rifampicin (RIF) and isoniazid (INH) resistance were detected by "TB-Biochip" test system. Resistance was significantly higher in patients with a history of treatment compared with patients were newly diagnosed. Initial and acquired resistance were 53% (499/940) and 87% (41/48) respectively. Initial multidrug-resistance (MDR) (both to RIF and INH) was 30% (282/940) and acquired MDR was 75% (35/48). The single primary drug resistance only to RIF was 3% (29/940), to INH was 20% (188/940). The single acquired drug resistance only to RIF was 4% (2/48), to INH was 8% (4/48). The most common point mutations in rpoB gene were in codon 531 (58%), 526 (18%), 516 (9%) and 511 (6.8%). The point mutation Ser531-->Leu was at the highest frequency (59.7%). Resistance to INH was associated mostly with mutations found in katG gene-90.5%, inhA gene-9.05% and ahpC gene-0.45%. Prevalence of mutation was found in katG gene-Ser315 Thr (88.7%). The rifampicin and isoniasid resistance of M. Tb strains isolated in Kyrgyzstan is associated mostly with Ser531-->Leu mutation of rpoB gene, Ser315-->Thr mutation of katG gene. The "TB-Biochip" test system is simple and rapid for detection of rifampicin-and isoniazid resistant of M. Tuberculosis. The biochip-based analysis of RIF and INH susceptibility provides fast (less than 24 hours) and accurate identification of the mutations in gene rpoB, katG, inhA, ahpC responsible for resistance to rifampin and isoniazid.