Prevalence and dissemination of the Ser315Thr substitution within the KatG enzyme in isoniazid-resistant strains of Mycobacterium tuberculosis isolated in Uruguay (original) (raw)
Related papers
Antimicrobial Agents and Chemotherapy, 2004
We investigated mutations in the genes katG, inhA (regulatory and structural regions), and kasA and the oxyR-ahpC intergenic region of 97 isoniazid (INH)-resistant and 60 INH-susceptible Mycobacterium tuberculosis isolates obtained in two states in Brazil: São Paulo and Paraná. PCR-single-strand conformational polymorphism (PCR-SSCP) was evaluated for screening mutations in regions of prevalence, including codons 315 and 463 of katG, the regulatory region and codons 16 and 94 of inhA, kasA, and the oxyR-ahpC intergenic region. DNA sequencing of PCR amplicons was performed for all isolates with altered PCR-SSCP profiles. Mutations in katG were found in 83 (85.6%) of the 97 INH-resistant isolates, including mutations in codon 315 that occurred in 60 (61.9%) of the INH-resistant isolates and 23 previously unreported katG mutations. Mutations in the inhA promoter region occurred in 25 (25.8%) of the INH-resistant isolates; 6.2% of the isolates had inhA structural gene mutations, and 10.3% had mutations in the oxyR-ahpC intergenic region (one, nucleotide ؊48, previously unreported). Polymorphisms in the kasA gene occurred in both INH-resistant and INH-susceptible isolates. The most frequent polymorphism encoded a G 269 A substitution. Although KatG 315 substitutions are predominant, novel mutations also appear to be responsible for INH resistance in the two states in Brazil. Since ca. 90.7% of the INH-resistant isolates had mutations identified by SSCP electrophoresis, this method may be a useful genotypic screen for INH resistance.
Jornal Brasileiro de Pneumologia, 2009
Objective: To analyze and compare the mutations in two different regions of the katG gene, which is responsible for isoniazid (INH) resistance. Methods: We analyzed 97 multidrug-resistant Mycobacterium tuberculosis strains isolated in cultures of sputum samples obtained from the Professor Hélio Fraga Referral Center, in Brasília, Brazil. Another 6 INH-sensitive strains did not present mutations and were included as controls. We used PCR to amplify two regions of the katG gene (GenBank accession no. U06258)-region 1, (from codon 1 to codon 119) and region 2 (from codon 267 to codon 504)-which were then sequenced in order to identify mutations. Results: Seven strains were resistant to INH and did not contain mutations in either region. Thirty strains carried mutations in region 1, which was characterized by a high number of deletions, especially at codon 4 (24 strains). Region 2 carried 83 point mutations, especially at codon 315, and there was a serine-to-threonine (AGC-to-ACC) substitution in 73 of those cases. The analysis of region 2 allowed INH resistance to be diagnosed in 81.4% of the strains. Nine strains had mutations exclusively in region 1, which allowed the proportion of INH-resistant strains identified to be increased to 90.6%. Conclusions: The number of mutations at codon 315 was high, which is consistent with cases described in Brazil and in other countries, and the analysis of region 1 resulted in a 9.2% increase in the rate at which mutations were identified.
Journal of Clinical Microbiology, 2002
We describe a simple multiplex allele-specific (MAS)-PCR assay to detect mutations in the second base of the katG gene codon 315, including AGC3ACC and ACA (Ser3Thr) substitutions that confer resistance to isoniazid (INH) in Mycobacterium tuberculosis clinical isolates. The 315 ACC allele is found in the majority of Inh r strains worldwide, especially in areas with a high incidence of tuberculosis. The 315 ACA allele is characteristic of the New York City multidrug-resistant (MDR) strain W and its progenies in the United States. The mutations in katG315 are revealed depending on the presence or absence of an indicative fragment amplified from the wild-type allele of this codon. Initially optimized on the purified DNA samples, the assay was then tested on crude cell lysates and auramine-stained sputum slide preparations with the same reproducibility and interpretability of profiles generated by agarose gel electrophoresis. The MAS-PCR assay can be used for the detection of resistance to INH in clinical laboratories in regions with a high prevalence of MDR M. tuberculosis strains.
Antimicrobial Agents and Chemotherapy, 2004
We investigated mutations in the genes katG, inhA (regulatory and structural regions), and kasA and the oxyR-ahpC intergenic region of 97 isoniazid (INH)-resistant and 60 INH-susceptible Mycobacterium tuberculosis isolates obtained in two states in Brazil: São Paulo and Paraná. PCR-single-strand conformational polymorphism (PCR-SSCP) was evaluated for screening mutations in regions of prevalence, including codons 315 and 463 of katG, the regulatory region and codons 16 and 94 of inhA, kasA, and the oxyR-ahpC intergenic region. DNA sequencing of PCR amplicons was performed for all isolates with altered PCR-SSCP profiles. Mutations in katG were found in 83 (85.6%) of the 97 INH-resistant isolates, including mutations in codon 315 that occurred in 60 (61.9%) of the INH-resistant isolates and 23 previously unreported katG mutations. Mutations in the inhA promoter region occurred in 25 (25.8%) of the INH-resistant isolates; 6.2% of the isolates had inhA structural gene mutations, and 10.3% had mutations in the oxyR-ahpC intergenic region (one, nucleotide ؊48, previously unreported). Polymorphisms in the kasA gene occurred in both INH-resistant and INH-susceptible isolates. The most frequent polymorphism encoded a G 269 A substitution. Although KatG 315 substitutions are predominant, novel mutations also appear to be responsible for INH resistance in the two states in Brazil. Since ca. 90.7% of the INH-resistant isolates had mutations identified by SSCP electrophoresis, this method may be a useful genotypic screen for INH resistance.
International Journal of Antimicrobial Agents, 2004
The prevalence of mutations in the katG, inhA and oxyR-ahpC genes of isoniazid (INH)-resistant Mycobacterium tuberculosis isolates in the Philippines were determined. Of 306 M. tuberculosis isolates studied, 81 (26.5%) exhibited INH-resistance. Forty-four strains (54.3%) had mutations in the katG gene, eighteen strains (22.2%) had mutations in the putative inhA locus region, seven had mutations in both regions and five strains had mutations in the oxyR-ahpC operon. Only seven strains had no mutations. A total of 71 of the 81 (87.6%) resistant strains and 65 of the 72 (90.3%) INH sensitive randomly selected strains showed amino acid substitution in codon 463 (Arg to Leu) (88.9%). This fact supports the hypothesis that mutations at codon 463 are independent of INH-resistance and are linked to the geographical origins of the strains.
katG (SER 315 THR) Gene Mutation in isoniazid resistant Mycobacterium tuberculosis
Kathmandu University …, 2012
Isoniazid (INH) together with Rifampicin (RFP) forms the cornerstone of a short chemotherapy course for tuberculosis (TB) treatment. Mutation at codon 315 of katG gene is most prevalent in isoniazid resistant Mycobacterium tuberculosis (MTB) and is high in area with high TB incidence. Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP) has been found to be a reliable and effective tool for the identification of the specific gene alteration.
BioMed Research International, 2015
Mutation at codon 315 ofkatGgene is the major cause for isoniazid (INH) resistance inMycobacterium tuberculosis(M. tuberculosis). Substitution at codon 315 ofkatGgene was analyzed in 85 phenotypically resistant isolates collected from various parts of southern India by direct sequencing method. The obtained results were interpreted in the context of minimum inhibitory concentration (MIC) of INH. Of the 85 phenotypically resistant isolates, 56 (66%) were also correlated by the presence of resistance mutations in thekatGgene; 47 of these isolates had ACC, 6 had AAC, 2 had ATC, and one had CGC codon. The frequency of Ser315 substitution inkatGgene was found to be higher (70%) amongst multidrug-resistant (MDR) strains than among non-MDR (61%) INH-resistant isolates. Further, the frequency of mutations was found to be greater (74%) in isolates with higher MIC values in contrast to those isolates with low MIC values (58%). Therefore, the study identified high prevalence of Ser315Thr subst...