Genetic diversity of Mycobacterium tuberculosis isolates from central India.

Desikan, P.; Chauhan, D.S.; Sharma, P.; Panwalkar, N.; Chourey, M.; Patidar, M.L.; Yadav, P.; Chandrasekaran, V.; Ohri, B.S.

Indian Journal of Medical Research; 2016; 143; 481-486.

Background & objectives : There is a paucity of data available on genetic biodiversity of Mycobacterium tuberculosis isolates from central India . The present study was carried out on isolates of M. tuberculosis cultured from diagnostic clinical samples of patients from Bhopal , central India , using spoligotyping as a method of molecular typing.

Methods : DNA was extracted from 340 isolates of M. tuberculosis from culture, confirmed as M. tuberculosis by molecular and biochemical methods and subjected to spoligotyping. The results were compared with the international SITVIT2 database.

Results : Sixty five different spoligo international type (SIT) patterns were observed. A total of 239 (70.3%) isolates could be clustered into 25 SITs. The Central Asian (CAS) and East African Indian (EAI) families were found to be the two major circulating families in this region. SIT26/CAS1_DEL was identified as the most predominant type, followed by SIT11/EAI3_IND and SIT288/CAS2. Forty (11.8%) unique (non-clustered) and 61 (17.9%) orphan isolates were identified in the study. There was no significant association of clustering with clinical and demographic characteristics of patients.

Interpretation & conclusions : Well established SITs were found to be predominant in our study. SIT26/CAS1_DEL was the most predominant type. However, the occurrence of a substantial number of orphan isolates may indicate the presence of active spatial and temporal evolutionary dynamics within the isolates of M. tuberculosis .

Keywords: Genetic diversity - Mycobacterium tuberculosis - polymorphism - spoligotyping

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