This study examines the intrinsic fitness burden associated with RNA polymerase (rpoB) mutations conferring rifampin resistance in Escherichia coli K12 (MG1655) and explores the nature of adaptation to the costs of resistance. Among 28 independent Rif(r) mutants, the per-generation fitness burden (in the absence of rifampin) ranged from 0 to 28%, with a median of 6.4%. We detected no relationsh...

Identification of Mycobacterium tuberculosis and Rifampin Resistance in Pulmonary Extra-pulmonary Clinical Specimens Using the Gene Xpert MTB/RIF Assay

Consecutive patient cultures (140) of Mycobacteriium tuberculosis were collected from five Russian civilian and prison tuberculosis laboratories and analyzed for rifampin (rpoB) and isoniazid resistance (inhA, katG, ahpC); transmission of Beijing family isolates; and the importance of prison and previous therapy in drug resistance. Rifampin, isoniazid, and multidrug resistance occurred in 58.2%...

There is a geographic distribution of Mycobacterium tuberculosis strains with various rpoB gene mutations that account for rifampin resistance. We studied 17 rifampin-resistant clinical isolates from patients in Greece to identify rpoB mutations. The aim of our study was the evaluation of a commercially available line probe assay kit (INNO-LiPA Rif. TB) to detect rpoB mutations and rifampin res...

The biochemical mechanism of resistance to kanamycin, viomycin, and rifampin in five clinical isolates of Mycobacterium tuberculosis was studied. Resistance to viomycin and kanamycin was attributed to altered ribosomes, whereas resistance to rifampin was attributed to an alteration of RNA polymerase. Ribosomal resistance was, however, not the only way of expressing resistance to viomycin and ka...

Although rifamycins have excellent activity against Chlamydophila pneumoniae and Chlamydia trachomatis in vitro, concerns about the possible development of resistance during therapy have discouraged their use for treatment of chlamydial infections. Rifalazil, a new semisynthetic rifamycin with a long half-life, is the most active antimicrobial against C. pneumoniae and C. trachomatis in vitro, ...

UNLABELLED Fitness costs play a key role in the evolutionary dynamics of antibiotic resistance in bacteria by generating selection against resistance in the absence of antibiotics. Although the genetic basis of antibiotic resistance is well understood, the precise molecular mechanisms linking the genetic basis of resistance to its fitness cost remain poorly characterized. Here, we examine how t...

Rifampin-resistant strains of group A streptococci were isolated as spontaneous mutants. Transduction analyses employing phage A25 showed the rifampin marker to be transferred with high frequency. The mutations conferring resistance to rifampin and streptomycin are not co-transducible.

To investigate the emergence of rifampin resistance in Rhodococcus equi strains isolated from foals and their environment in Japan, we compared the in vitro antimicrobial susceptibilities to rifampin of 640 isolates from 64 infected foals and 98 soil isolates from their horse-breeding farms. As a control, 39 human isolates from patients with and without AIDS were also tested for susceptibility ...

Rifampin is a cornerstone of modern antituberculosis therapy. However, rifampin's half-life of 3 h is believed to limit its utility for intermittent therapy, so new congeners with long half-lives are being developed. Using an in vitro pharmacokinetic-pharmacodynamic model of tuberculosis, we examined the relationships between rifampin exposure, microbial killing of log-phase-growth Mycobacteriu...