Resistance levels and rpoB gene mutations among in vitro-selected rifampin-resistant Mycobacterium tuberculosis mutants

Abstract

The distribution and resistance levels of 189 in vitro-selected rifampin-resistant Mycobacterium tuberculosis mutants of Beijing and other genotypes were determined. Apart from a higher amount of codon 522 point mutations and large deletions, a spread of mutations similar to that reported for clinical isolates was seen. Most mutations were correlated with high-level resistance; a lower level, or a MIC of <16 mg/liter, was associated with codon 522 mutations. Multiple mutations were detected in two Beijing mutants.

FIG. 1.

Distribution of in vitro-selected, rpoB mutation sites in 89 Beijing and 99 non-Beijing genotype M. tuberculosis mutants. The mutant lacking an RRDR mutation is not included. tot, total; SNP's, single nucleotide polymorphism.