Investigation of epidemiological characteristics and molecular mechanisms of moxifloxacin resistance in mycobacterium tuberculosis strains isolated from pulmonary tuberculosis patients

Objective: In this study, it is aimed to determine the moxifloxacin sensitivities of Mycobacterium tuberculosis strains isolated in our region and to specify the regional resistance rates besides to investigate the relation of phenotypical resistance with mutations in gyrA gene. Materials and Method: Sequential 100 isolates that are seen to be non-multi drug resistant and 37 isolates that are determined as multidrug resistant among Mycobacterium tuberculosis strains isolated from pulmonary tuberculosis patient's samples which sent to Region Tuberculosis Laboratory of Adana were included in this study. Drug sensitivity rates and DNA Sequencing of gyrA region of these isolates are compared again. Findings: Resistance to moxifloxacin is found in 25 of 137 (18,2 %) isolates of which phenotypic susceptibilities were tested. Resistance rates among strains which seen to have multidrug resistance and those which have not multidrug resistance were 17 % and 21,6 % respectively. Looking at the distribution according to regions which sent 25 clinical isolates; it is determined that 10 of isolates were belonged to Adana, 6 to Gaziantep, 5 to Hatay, 3 to Mersin and 1 to Kahramanmaraş province. Among all isolates included in study, Single bases mutation was encountered in 6 samples in total according to DNA sequencing result of gyrA region. The positions of mutations were identified as Asp94Tyr, Asp94Gly, Ala90Val, Gly88Ala and in 2 samples as Asp89Asn. Two of the samples which mutation is seen were found to be sensitive to moxifloxacin phenotypically. Result: At the end of our study it is determined that, resistance developed to moxifloxacin would not be secondary in the treatment of tuberculosis. It is seen that different molecular mechanisms will be responsible from high resistance and the relation between resistance and mutations in the analysed gene is insufficient. It is concluded that research on moxifloxacin resistance should be continue with wider case groups and isolates also it will be important to persistently explain that there is a probability of resistance development in a short time to these group of drugs and it is required to use them more limited in non-spesific indications. Keywords: gyrA, Moxifloxacin, Mutation, Mycobacterium tuberculosis, Proportion.