The introduction of novel drugs into treatment must be accompanied by continuous phenotypic susceptibility testing and the analysis of genetic determinants of resistance.

BackgroundTuberculosis (TB) poses a worldwide threat due to advancing multidrug-resistant strains and deadly co-infections with Human immunodeficiency virus. Today large amounts of Mycobacterium tuberculosis whole genome sequencing data are being assessed broadly and yet there exists no comprehensive online resource that connects M. tuberculosis genome variants with geographic origin, with drug resistance or with clinical outcome.DescriptionHere we describe a broadly inclusive unifying Genome-wide Mycobacterium tuberculosis Variation (GMTV) database, (http://mtb.dobzhanskycenter.org) that catalogues genome variations of M. tuberculosis strains collected across Russia. GMTV contains a broad spectrum of data derived from different sources and related to M. tuberculosis molecular biology, epidemiology, TB clinical outcome, year and place of isolation, drug resistance profiles and displays the variants across the genome using a dedicated genome browser. GMTV database, which includes 1084 genomes and over 69,000 SNP or Indel variants, can be queried about M. tuberculosis genome variation and putative associations with drug resistance, geographical origin, and clinical stages and outcomes.ConclusionsImplementation of GMTV tracks the pattern of changes of M. tuberculosis strains in different geographical areas, facilitates disease gene discoveries associated with drug resistance or different clinical sequelae, and automates comparative genomic analyses among M. tuberculosis strains.

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The purpose of the present study was to analyse mutations in the gyrA and gyrB genes of Mycobacterium tuberculosis and define the possible correlation between these mutations and resistance to levofloxacin (LVX), moxifloxacin (MFX) and gatifloxacin (GAT), based on their MICs. One hundred and forty-two M. tuberculosis clinical isolates were collected from pulmonary tuberculosis patients in the Moscow region. All M. tuberculosis strains were tested for drug susceptibility to rifampicin and isoniazid using the BACTEC MGIT 960 System and to ofloxacin (OFX) using the absolute concentration method on solid Lowenstein-Jensen slants. All in all, 68 strains were selected at random (38 strains were resistant and 30 were susceptible to OFX) for further analysis using the TB-BIOCHIP-2 test system and DNA sequence analysis. The MICs of LVX, MFX and GAT for selected strains were determined using the BACTEC MGIT 960 System. Mutations in the gyrA gene were observed in 36 out of 38 (94.7 %) OFX-resistant M. tuberculosis strains. Asn538Asp and Asp500His substitutions in the gyrB gene only were found in two (5.3 %) strains. Twenty-nine out of 30 OFX-sensitive M. tuberculosis strains had no mutations in either gene. One (3.3 %) OFX-sensitive M. tuberculosis strain carried an Arg485His substitution in gyrB. The results of our investigation showed that there is no clear correlation between the type of mutation in the genes gyrA and gyrB, and the MIC levels of LVX, MFX and GAT for resistant strains. Mutations in gyrA and Asn538Asp, and Asp500His substitutions in gyrB were associated with cross-resistance of M. tuberculosis to fluoroquinolones. The substitution Arg485His in gyrB does not confer resistance to LVX, MFX and GAT in M. tuberculosis. INTRODUCTIONFluoroquinolones (FQs) are highly active antimicrobial agents, which are widely used in chemotherapy against multidrug-resistant (MDR) tuberculosis (TB). However, the application of ofloxacin (OFX), ciprofloxacin and levofloxacin (LVX) for the treatment of undiagnosed respiratory infections led to the development of resistance in Mycobacterium tuberculosis isolates (Wang et al., 2007). Moreover, the initial occurrences of resistance to FQs were observed in MDR strains and isoniazid (IHN)-and rifampicin (RIF)-susceptible strains isolated from newly diagnosed TB patients (Delgado & Telenti, 1996;Xu et al., 2009).The most promising drugs undergoing phase III trials are the fourth generation FQs, such as moxifloxacin (MFX) and gatifloxacin (GAT), which demonstrated high in vivo and in vitro activities against MDR strains and OFX-resistant and ciprofloxacin-resistant MDR strains (Zhao et al., 1999;Rodríguez et al., 2002;Poissy et al., 2010;Merle et al., 2012).Recent studies have shown that resistance to all FQs is due to mutations (single nucleotide polymorphisms, SNPs) not only in the gyrA (320 bp) gene, but also in the gyrB (375 bp) gene, which encode the respective subunits of the DNA topoisomerase gyrase (Takiff et al., 1994;Ginsburg et al., 2003;Shi et al., 2006;Lau et al., 2011). Th...

Our study shows that the eis promoter region is a useful molecular marker of kanamycin resistance in the Moscow region. Complex analysis of rrs and eis mutations will significantly reduce the time to diagnose kanamycin resistance in TB patients, compared with phenotypic drug resistance testing.