[Comparing performance of "TB-BIOCHIP", "Xpert MTB/RIF" and "genotype MTBDRplus" assays for fast identification of mutations in the Mycobacterium tuberculosis complex in sputum from TB patients].

The frequency of mutations causing drug resistance in MTB isolates were studied in the respiratory material obtained from TB-patients in the Moscow Region. In izoniazid-resistant isolates, the most prevalent mutation was found to be the Ser315Thr substitution in the katG gene (15.8%) whereas the most frequent mutations in multidrug-resistant isolates were Ser531Leu and Ser315Thr in the rpoB and katG genes (26.3%), or a combination of these two substitutions with a T15 mutation in the inhA gene (5.3%). We compared performance of three molecular assays--"TB-BIOCHIP" ("BIOCHIP-IMB", Ltd, Russia), Xpert MTB/RIF ("Cepheid", USA) and GenoType MTBDRplus ("Hain Life-science", Germany), with the efficiency of luminescent microscopy, and phenotypic drug-suscepibility testing in an automated system BACTEC MGIT 960 (Becton, Disckinson and Company, USA). Xpert MTB/RIF, TB-BIOCHIP and GenoType MTBDRplus detected MTB in sputum in 92, 78 and 49% of all culture-positive cases, respectively. The agreement between standard cultural data and molecular DST results for Xpert MTB/RIF (resistance towards rifampicin), for TB-BIOCHIP and GenoType MTBDRplus (resistance towards rifampicin and izoniazid) amounted to 100, 97 and 100% respectively. Summing up, Xpert MTB/RIF was concluded to be the most efficient assay for primary detection of MTB, whereas the TB-BIOCHIP was shown to be the only molecular assay sensitive enough for simultaneous detection of MTB DNA and for revealing multidrug resistance in sputum (i.e. resistance to both first-line anti-TB drugs, rifampicin and izoniazid).

[Use of molecular-biological microchip TB-BIOCHIP-2 for detecting of Mycobacterium tuberculosis with multidrug resistance to fluoroquinolones in patients with new detected and chronic tuberculosis].

At present the left-handed "respiratory" quinolones such as moxifloxacin and levofloxacin are the most promising drugs for therapy of multidrug resistant tuberculosis (MDR). Fast and specific diagnostics of sensitivity of M. tuberculosis (MBT) with MDR to this group of drugs is required for timely prescription of adequate chemotherapy and its correction in case of MBT resistance to fluoroquinolones. A new generation of biological microchips - TB-BIOCHIP-2 makes possible to detect 9 mutation types in quinolones resistant determination region (QRDR) of gene. About 800 samples from 169 patients in Antituberculosis center were studied. In patients with new detected tuberculosis 23.5% MBT resistant to isoniazid and rifampicin (MDR) and sensitive to fluoroquinolones were revealed. In patients with chronic tuberculosis 65.5% MBT-MDR were revealed. Our results were confirmed with detecting ofloxacin resistance on Lowenstein - Jensen. In addition efficiency of TB-BIOCHIP-2 to control drug testing sensitivity of MBT-MDR on fluoroquinolones was confirmed.

[Investigation of Mycobacterium tuberculosis sensitivity to fluoroquinolone, by revealing gyrA gene mutations].

The resistance of Mycobacterium tuberculosis (MBT) to fluoroquinolones is associated with the mutations concentrated in the gyrA gene that is a structural gene of a gyrase A subunit. Detection of mutations in this portion of the gene allows the sensitivity of MBT to this group of drugs to be rapidly determined.

[The characteristics of the sensitivity of Mycobacterium tuberculosis to rifampicin and isoniazid through determination of mutations in the genes rpoB, katG, inhA, oxyR, and kasA by different molecular biological assays].

Two hundred and two patients with different forms of pulmonary tuberculosis were examined to study the characteristics of sensitivity with the signs of multidrug resistance to rifampicin and isoniazid, by using a microbiological assay of the absolute concentrations and determining mutations in the genes rpoB, katG, inhA, oxyR, and kasA, by employing different molecular biological assays. Mycobacterium tuberculosis (MBT) DNA was isolated from both a diagnostic material (such as sputum, bronchial secretion), and clinical MBT isolates. By showing a higher sensitivity and a higher specificity, as cultural techniques, molecular biological assays of MBT drug sensitivity in patients with tuberculosis were ascertained to accelerate its diagnosis until the patient was admitted to a clinic.

[New technologies in the determination of drug susceptibility in Mycobacterium tuberculosis]. / Novye tekhnologii opredeleniia lekarstvennoi chuvstvitel'nosti Mycobacterium tuberculosis.

A variety of mutations in the genes rpoB, katG, inhA, ahpC, kasA was studied by using different molecular biological methods (conformational polymorphism of single-chain fragments, heteroduplex analysis, biochips) in rifampicin- and isoniazid-resistant Mycobacterium tuberculosis (MBT) strains isolated from patients with pulmonary tuberculosis. Twenty-nine mutation combinations were identified in the MBT strains. The use of biochips is the most promising method for identifying the type of mutations responsible for the simultaneous resistance to rifampicin and isoniazid. Detection of several MBT strains in one patient requires the use a combination of molecular biological and microbiological studies.