[The Spectrum of Mutations in Genes Associated with Resistance to Rifampicin, Isoniazid, and Fluoroquinolones in the Clinical Strains of M. tuberculosis Reflects the Transmissibility of Mutant Clones].

To study the transmissibility of drug resistant mutant clones, M. tuberculosis samples were isolated from the patients of the clinical department and the polyclinic of the Central TB Research Institute (n = 1455) for 2011-2014. A number of clones were phenotypically resistant to rifampicin (n = 829), isoniazid (n = 968), and fluoroquinolones (n = 220). We have detected 21 resistance-associated variants in eight codons of rpoB, six variants in three codons of katG, three variants in two positions of inhA, four variants in four positions of ahpC, and nine variants in five codons of gyrA, which were represented in the analyzed samples with varied frequencies. Most common mutations were rpoB 531 Ser→Leu (77.93%), katG 315 (Ser→Thr) (94.11%), and gyrA 94 (Asp→Gly) (45.45%). We found that the mutations at position 15 of inhA (C→T) (frequency of 25.72%) are commonly associated with katG 315 (Ser→Thr). This association of two DNA variants may arise due to the double selection by coexposure of M. tuberculosis to isoniazid and ethionamide. The high transmissibility of mutated strains was observed, which may be explained by the minimal influence of the resistance determinants on strain viability. The high transmissibility of resistant variants may also explain the large populational prevalence of drug-resistant TB strains.

Antibacterial Effects of Liposomes Containing Phospholipid Cardiolipin and Fluoroquinolone Levofloxacin on Mycobacterium tuberculosis with Extensive Drug Resistance.

The effects of liposomes containing phospholipid cardiolipin without antibiotic and loaded with levofloxacin on the growth of Mycobacterium tuberculosis with extensive drug resistance were studied in vitro. Liposomes consisting of cardiolipin alone in a concentration of 335 µM completely suppressed the growth of M. tuberculosis. In order to reduce the minimum inhibitory concentration of cardiolipin, complex liposome preparation consisting of phosphatidylcholin/cholesterol/cardiolipin and loaded with levofloxacin was prepared. Due to this, the cardiolipin concentration was reduced to 33.5 µM (50 µg/ml) and concentration of levofloxacin - to 2 µg/ml.

Performance of Cepheid ® Xpert MTB/RIF ® and TB-Biochip ® MDR in two regions of Russia with a high prevalence of drug-resistant tuberculosis.

The purpose of this study was to assess the performance of Cepheid® Xpert MTB/RIF® ("Xpert") and TB-Biochip® MDR ("TB-Biochip"). Sputum specimens from adults with presumptive tuberculosis (TB) were homogenized and split for: (1) direct Xpert and microscopy, and (2) concentration for Xpert, microscopy, culture [Lowenstein-Jensen (LJ) solid media and Mycobacteria Growth Indicator Tube® (MGIT)], indirect drug susceptibility testing (DST) using the absolute concentration method and MGIT, and TB-Biochip. In total, 109 of 238 (45.8 %) specimens were culture-positive for Mycobacterium tuberculosis complex (MTBC), and, of these, 67 isolates were rifampicin resistant (RIF-R) by phenotypic DST and 64/67 (95.5 %) were isoniazid resistant (INH-R). Compared to culture of the same specimen, a single direct Xpert was more sensitive for detecting MTBC [95.3 %, 95 % confidence interval (CI), 90.0-98.3 %] than direct (59.6 %, 95 % CI, 50.2-68.5 %) or concentrated smear (85.3 %, 95 % CI, 77.7-91.1 %) or LJ culture (80.8 %, 95 % CI, 72.4-87.5 %); the specificity was 86.0 % (95 % CI, 78.9-91.3 %). Compared with MGIT DST, Xpert correctly identified 98.2 % (95 % CI, 91.5-99.9 %) of RIF-R and 95.5 % (95 % CI, 85.8-99.2 %) of RIF-susceptible (RIF-S) specimens. In a subset of 104 specimens, the sensitivity of TB-Biochip for MTBC detection compared to culture was 97.3 % (95 % CI, 91.0-99.5 %); the specificity was 78.1 % (95 % CI, 61.5-89.9 %). TB-Biochip correctly identified 100 % (95 % CI, 94.2-100 %) of RIF-R, 94.7 % (95 % CI, 76.7-99.7 %) of RIF-S, 98.2 % (95 % CI, 91.4-99.9 %) of INH-R, and 78.6 % (95 % CI, 52.1-94.2 %) of INH-S specimens compared to MGIT DST. Xpert and Biochip were similar in accuracy for detecting MTBC and RIF resistance compared to conventional culture methods.

Carbocyclic analogues of inosine-5'-monophosphate: synthesis and biological activity.

9-(4'-Phosphonomethoxy-2'-cyclopenten-1'-yl)hypoxanthine and 9-(4'-phosphonomethoxy-2',3'-dihydroxycyclopenten-1'-yl)hypoxanthine were synthesized as isosteric carbocyclic analogues of inosine-5'-monophosphate. The synthesized compounds were shown to be capable of inhibiting the activity of human type II inosine-5'-monophosphate dehydrogenase (IMPDH II) (IC(50 )= 500 µM) and to have no significant effects on the growth ofMycobacterium tuberculosis.