Transcriptome analysis of Mycobacterium tuberculosis clinical isolates.

Bacterial persister cells are phenotypic variants of regular cells that are tolerant to antibiotics. Analysis of clinical isolates of M. tuberculosis showed that strains vary substantially in their tolerance to antibiotics. The level of persisters was very high is some isolates, suggesting that these are hip mutants. We investigated gene expression differences in eight clinical isolates, four of which we characterized as high-persister strains and four as low-persister, or regular, strains. Comparison of gene expression patterns may provide clues as to the genetic mechanisms underlying persister formation. Exponential phase cultures of eight clinical isolates were challenged in biological triplicate with the antibiotic D-cycloserine and cells were colllected at Day 0 and Day 7 for transcriptome analysis.