embB gene mutations associated withethambutol resistance in Indian strainsof Mycobacterium tuberculosis

摘要

Ethambutol (EMB) mono-resistance does not occurfrequently and scanty data are available regarding theresistance mechanism of EMB. The present studyanalyses mutations in the embB gene in EMB-resistantIndian isolates of Mycobacterium tuberculosis. Thirty-seven isolates were collected from different parts ofIndia and the 364 bp of embB gene involved in resistanceto EMB was amplified by PCR and subjected to single-stranded conformational polymorphism (SSCP). Mutations associated with EMB resistance were found tobe present mostly with isoniazid and rifampicin. SSCPshowed altered mobility in 30/37 isolates. The mostcommon mutation was observed at codon 306 in 9/22isolates followed by 299 in 6/22 isolates. We havefound novel mutations not reported so far at codon239, 257, 282, 296, 299, 304 and 311. SSCP revealed 22(73.3%) isolates had mutation in the 364 bp fragmentof embB gene. Our results suggest that alterations inamino acid sequence could be present from position239 to 311 and functional analysis of the genetic variantsof embB protein may provide a possible mechanismfor EMB resistance.