Comparative asessment of bacterial excrection degree depending from sensivity profile of Mycobacterium tuberculosis to antituberculosis drugs

Abstract

One of the important part of the epidemiological component of tuberculosis pathomorphosis in modern conditions is the change in important biological properties of the pathogen, not only in the form of increased frequency and extension of Mycobacterium tuberculosis resistance to anti-tuberculosis drugs, but also changes in manifestations of vital activity - virulence, massivity and growth rate of culture, etc. The study purpose was to determine the growth intensity of Mycobacterium tuberculosis depending on resistance to anti-tubercuosis drugs, to assess the bacterial excretions, to compare the data of the phenotypic (Löwenstein-Jensen media) and genotypic method (Xpert MTB/RIF), to carry out the correlation analysis of the results. Materials and methods: The results of the phenotypic and genotypic tests of 148 samples have been analyzed. Group 1 included 52 samples with susceptibility of Mycobacterium tuberculosis to anti-tuberculosis drugs, group 2 - 38 samples with monoresistance to isoniazid, group 3 - 58 samples with multi-drug resistance. The bacterial excretion was assessed as: scanty - for single colonies, moderate - for 20 to 100 colonies, massive - for 100 and over. The standard assessment of positive genotypic testing by quantities of DNA copies: very small, small, moderate, great quantity. Correlation analysis has been made in SPPS static program. Results: In the 1 group results the following bacterial excretions have been noted: 30,7%- scanty, 28,8%-moderate, 40,3% massive. In the 2 group scanty bacterial excretion was identified in 36,8%, moderate in 39,1%, massive in 23,6%. In the 3 group scanty in 37,9%, moderate in 22,4% and massive bacterial excretion in 39,6%. In the genotypic testing 15 negative results have been noted, which comprised 7,7% in 1 group, 15,8%, in 2 group, 8,6% in 3 group.Very small quantity in 6,2%, 15,6%, 11,3%, Small in 27,1%, 28,1%, 28,3%, Medium quantity in 42,1%, 34,4%, 26,4%, Great quantity in 31,2%, 21,5%, 32,1% - in 1, 2, 3 group, respectively. Conclusions: Samples with different resistant strains demonstrated differs in phenotypic and genotypic features. Phenotypic method gave the possibility to detect more than 10% cases with bacterial excretion, that had negative genotypic test. Correlation analysis showed a strong and significant correlation between the indicated results, the Spirmen correlation is 0.75, Kendall - 0.66, with the reliability level p˂0.01. Inclusion of the results of genotypic test with information on the quantity of Mycobacterium tuberculosis genetic material in a patient's sputum sample, and also on Mycobacteria tuberculosis resistance, into the assessment of the tuberculosis infection hotbed will enable improvement of epidemiological control.