Role of embB codon 306 mutations in Mycobacterium tuberculosis revisited: A novel association with broad drug resistance and IS6110 clustering rather than ethambutol resistance

Abstract

Mutations at position 306 of embB (embB306) have been proposed as a marker for ethambutol resistance in Mycobacterium tuberculosis; however, recent reports of embB306 mutations in ethambutol-susceptible isolates caused us to question the biological role of this mutation. We tested 1,020 clinical M. tuberculosis isolates with different drug susceptibility patterns and of different geographical origins for associations between embB306 mutations, drug resistance patterns, and major genetic group. One hundred isolates (10%) contained a mutation in embB306; however, only 55 of these mutants were ethambutol resistant. Mutations in embB306 could not be uniquely associated with any particular type o..