Determination of principal genotypic groups among susceptible, MDR and XDR clinical isolates of Mycobacterium tuberculosis in Belarus and Iran.

INTRODUCTION: All members of the Mycobacterium tuberculosis complex were assigned to one of the three principle genetic groups based on KatG463/GyrA95 polymorphism.

MATERIALS AND METHODS: A total of 202 isolates of M. tuberculosis consisting of 50 susceptible, 121 MDR (multidrug resistant) and 31 XDR (extensively drug resistant) isolated from culture-confirmed tuberculosis patients in different regions of Belarus and Iran (Tehran and Markazi province). Isolates were screened by sequencing and polymerase chain reaction restriction fragment length polymorphism (RFLP) assay, and were further divided into three principal genetic groups (PGG), based on Sreevatsan's pattern as polymorphisms in KatG463/GyrA95 codons.

RESULTS: Among the 104 isolates, characterized as MDR from Belarus, 57 (54.8 ± 4.8%), 30 (28.8 ± 4.43%), 17 (16.3 ± 3.6), belonged to PGG 1, 2, and 3, respectively (p< 0.05). Thirty one XDR isolates from Belarus had a similar pattern as 15 (48.4%), 12 (38.7%), 4 (12.9%) PGG 1, 2, and 3, respectively. From Iranian samples, Markazi isolates (susceptible to drugs) had a pattern as 12 (36.5%), 15 (45.5%), 3 (6%), and Tehran samples were (selected MDR): 9 (53%), 6 (35.2%), 2 (11.8%) (PGG 1, 2, and 3, respectively). In a study of tuberculosis patients, who were in prison, no relation was found between PGG and resistance to isoniazid, but most of the identified isolates belonged to PGG 1 (45.5 ± 10.9%) (p< 0.05). Overall, the group 1 isolates showed more frequency in MDR and XDR rather than susceptible strains, and there aren't any relations to geographic region.