MIRU-VNTR genotyping of Mycobacterium tuberculosis strains from central region of Russia
Abstract number: P1553
Afanas'ev M., Ilina E., Smirnova T., Larionova E., Kuzmin A., Andreevskaya S., Chernousova L., Govorun V.
Objectives: The Russian Federation is one of the world's areas most affected by a high incidence of tuberculosis (TB). Although TB morbidity decreased slightly in recent years, the situation remains alarming due to a major increase in the incidence and prevalence of multidrug-resistant TB (MDR-TB). The purposes of this study were to evaluate epidemiological diversity and MDR spreading among M. tuberculosis strains, circulated in the Central region of Russian Federation.
Methods:M. tuberculosis strains (n = 35) from sputum of epidemiologically unrelated TB patients from Moscow were selected for study. Species identification and drug susceptibility testing to main antituberculosis drugs rifampicin (RIF) and isoniazid (INH) were performed according to the WHO recommended protocols. Standard procedure of MIRU-VNTR typing was carried out as described previously. For detection of specific SNPs causing drug resistance minisequencing reaction followed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) of the reaction products was used.
Results: Among 65 M. tuberculosis strains 33 (50.8%) were identified as MDR (i.e. resistant to both RIF and INH), 19 (29.2%) were susceptible to RIF and INH, and 13 (20.0%) were resistant to INH only. Mutations in the RRDR of the rpoB gene were detected in all RIF-resistant strains. The Ser531Leu substitution was prevalent among them (24/33, 72.7%). Aberrations in the Ser315 codon of katG and/or in the inhA promoter region were found in 41 (89.1%) of 46 INH-resistant strains. Most of them (33/46, 71.7%) had the mutation Ser315Thr. Thirty five different MIRU-VNTR profiles were identified, including the 27 unique ones. 8 clusters (from 2 to 11 strains in each one) enclosed the 38 strains. Mutations associated with the MDR-phenotype were found more frequently in strains grouped in clusters (23/38; 60.5%), than for strains with unique MIRU-VNTR profiles (10/27; 37.1%). (Chi2 for trend 4.4; P < 0.05).
Conclusion: Those strains grouped into the main VNTR clusters and had the MIRU profiles 223325153533, 223325173533 or 223425173533 are associated with MDR-phenotype. It is possible that the spreading of such strains is related with secondary-acquired resistance and plays a significant role in increasing of MDR TB in the Central region of Russia.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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