Quinolones are a large and widely consumed class of synthetic drugs. Expanded-spectrum quinolones, like ciprofloxacin are highly effective against Gram-negative bacteria, especially Escherichia coli. In E. coli the major target for quinolones is DNA gyrase. This enzyme is composed of two subunits, GyrA and GyrB encoding by gyrA and gyrB, respectively. Mutations in either of these genes cause qu...

Killing of Escherichia coli by hydrogen peroxide proceeds by two modes. Mode one killing appears to be due to DNA damage, has a maximum near 1 to 3 mM H2O2, and requires active metabolism during exposure. Mode two killing is due to uncharacterized damage, occurs in the absence of metabolism, and exhibits a classical multiple-order dose-response curve up to at least 50 mM H2O2 (J. A. Imlay and S...

Multiplex allele-specific PCRs detecting katG codon 315 and mabA (bp -15) mutations could specifically identify 77.5% of isoniazid-resistant Mycobacterium tuberculosis strains in the South China region. One clinical isolate harboring InhA Ile194Thr was characterized to show strong association with isoniazid resistance in Mycobacterium tuberculosis.

objective(s) isoniazid (inh) is one of the main first line drugs used in treatment of tuberculosis and development of resistance against this compound can result in serious problems in treatment procedures. resistance to inh is mediated mainly by mutation in katg gene that is coded for the catalase enzyme. the proportional method for detection of inh-resistance is time consuming due to the slow...

We identified the genome sequences of two Mycobacterium tuberculosis isolates. They were resistant to rifampin and isoniazid, as determined by the agar proportion method, but were susceptible to isoniazid, as determined by the DNA array method. The genome sequences showed that a katG deletion led to the false diagnosis of isoniazid resistance by DNA array.

Genotypic analysis of 103 multidrug-resistant Mycobacterium tuberculosis strains isolated in Germany in 2001 revealed that mutations in codon 531 (75.7%) of the rpoB gene and codon 315 (88.4%) of the katG gene are most frequent. Beijing genotype strains (60.2% of all isolates) displayed a different distribution of resistance mutations than non-Beijing strains.

Catalase-peroxidases (KatGs) are unique bifunctional heme peroxidases with an additional posttranslationally formed redox-active Met-Tyr-Trp cofactor that is essential for catalase activity. On the basis of studies of bacterial KatGs, controversial mechanisms of hydrogen peroxide oxidation were proposed. The recent discovery of eukaryotic KatGs with differing pH optima of catalase activity now ...

BACKGROUND The objectives of the study were to compare the performance of line probe assay (GenoType MTBDRplus) with solid culture method for an early diagnosis of multidrug resistant tuberculosis (MDR-TB), and to study the mutation patterns associated with rpoB, katG and inhA genes at a tertiary care centre in north India. METHODS In this cross-sectional study, 269 previously treated sputum-...

plants showing root and crown rot were collected from 48 bean fields in the khuzestan and markazi provinces during 2005-2006. using specific primers (fsphr/fsphf) for these forma specialis, three isolates were identified as f.s. f.sp. phaseoli. conidial suspension of one of these isolates were irradiated (in a 60co- gamma cell with activity of 2500 curi and 0.38 grey per second dose rates) with...

The ahpC genes of 57 clinical isolates and one in vitro mutant of Mycobacterium tuberculosis were evaluated by nucleotide sequence analyses. Although compensatory ahpC promoter mutations were identified in 8 catalase-negative, katG-defective strains, the ahpC genes of 25 catalase-positive, isoniazid-resistant isolates and 25 drug-sensitive strains were not altered.