Genetic polymorphism and phenotypic resistance of Mycobacterium tuberculosis to fluoroquinolones of different generations

Abstract

Genetic polymorphism and phenotypic resistance of <i>Mycobacterium tuberculosis</i> to fluoroquinolones of different generations <b>Background:</b> The widespread use of molecular genetic methods for testing drug resistance of MBT to fluoroquinolones requires an assessment of the relevance of these results to the phenotypic manifestation of resistance. <b>Objectives:</b> Тo identify genetic determinants of MBT resistance to levofloxacin and moxifloxacin and to compare them with phenotypic resistance to these drugs. <b>Material and methods:</b> Genetic profiles of drug resistance of 95&nbsp;MBT isolates were built from microarray test system TB-TEST (BIOCIP-IMB, Russia) data. Phenotypic DST for levofloxacin and moxifloxacin was performed using BACTEC MGIT 960 (critical concentrations – 1,5 and 2,0 mg / l, resp.). <b>Results:</b> The relationship between the genetic profile of the isolates and the phenotypic resistance to levofloxacin and moxifloxacin are listed in Table 1. For moxifloxacin the agreement between these two methods coincides in 85%. However, in the case of levofloxacin, the match is only 52%. Thus, levofloxacin does not show a strong correlation between gyrA mutations and phenotypic resistance. <b>Conclusion:</b> Using exclusively molecular genetic methods to determine the resistance of Mtb to fluoroquinolones is not possible. It is necessary to confirm the results obtained by the phenotyping DST.