Characterization of a Clone of Mycobacterium tuberculosis Clinical Isolates with Mutations in KatG (A110V), EthA (Q269STOP), and the inhA Promoter (-15C→T).
Ontology highlight
ABSTRACT:
SUBMITTER: Brossier F
PROVIDER: S-EPMC4540911 | biostudies-literature | 2015 Sep
REPOSITORIES: biostudies-literature
Publications
Characterization of a Clone of Mycobacterium tuberculosis Clinical Isolates with Mutations in KatG (A110V), EthA (Q269STOP), and the inhA Promoter (-15C→T).
Brossier Florence F Sola Christophe C Bernard Christine C Jarlier Vincent V Veziris Nicolas N Sougakoff Wladimir W
Journal of clinical microbiology 20150708 9
Similar Datasets
Project description:The presence of mutations in specific regions of the katG, inhA, and ahpC genes was analyzed with 69 Mycobacterium tuberculosis isoniazid-resistant isolates from three Brazilian states. Point mutations in codon 315 of the katG gene were observed in 87.1, 60.9, and 60% of the isolates from Rio Grande do Sul, Rio de Janeiro, and São Paulo, respectively. Mutations in the inhA gene were identified only in one isolate from RJ State, and the ahpC promoter region revealed mutations in distinct positions in 12.9, 21.7, and 6.7% of the isolates from RS, RJ and SP, respectively.
| S-EPMC193791 | biostudies-literature
Project description:BackgroundThe acquisition of isoniazid (INH) resistance is alarming, considering its importance as a key drug that forms the core of multidrug treatment regimens for tuberculosis (TB). Genetic mutations in the katG and inhA promoter regions play crucial roles in INH resistance, but their prevalence varies geographically. This study aimed to identify the most common mutations in the katG and inhA genes in INH-resistant (INH-R) Mycobacterium tuberculosis (MTB) clinical isolates in Cameroon. The research also explored the relationships between these mutations and patients' demographics (age, sex, and sample type).MethodsWe conducted a retrospective cross-sectional laboratory-based study on 500 INH-R isolates (with or without resistance to other first-line drugs) at the National Tuberculosis Reference Laboratory (NTRL) in Cameroon between January 2014 and December 2020. GenoType MTBDRplus assay was performed on the retrieved isolates and the frequency of katG and inhA mutations were calculated. Chi-square tests were utilized to assess the associations between these mutations and patients' age, sex and sample type.ResultsA total of 410 (85.8%) culture-positive MTB isolates were analyzed, with a male-to-female ratio of 228 (55.6%) to 182 (44.4%) and an average age of 36.3 ± 13.4 years. Mutations in the katG and inhA genes were detected in 354 (86.3%) of cases, while 56 (13.7%) showed no mutations. Among the INH-R isolates, mutations in katG, inhA, and dual katG and inhA genes were present in 247 (60.2%), 76 (18.5%), and 31 (7.6%) isolates, respectively. Our analysis revealed significant associations between mutation prevalence and patient characteristics.ConclusionThis study reaffirmed the importance of the katG S315T substitution as a key indicator of INH resistance, with the inhA C-15T mutation providing additional support. However, a notable proportion of isoniazid-resistant isolates did not exhibit these mutations, underscoring the need to comprehend resistance mechanisms. Given that these mechanisms are strongly associated with varying levels of INH resistance, it is crucial that TB management strategies incorporate genetic profiling alongside patient demographics to optimize treatment outcomes and enhance control measures.
| S-EPMC11892131 | biostudies-literature
Project description:Screening strategies for antituberculosis compounds using Mycobacterium tuberculosis are time consuming and require biosafety level 3 (BSL3) facilities, which makes the development of high-throughput assays difficult and expensive. Mycobacterium marinum, a close genetic relative of M. tuberculosis, possesses several advantages as a suitable model for tuberculosis drug screening. However, despite the high genetic similarity, there are some obvious differences in susceptibility to some tuberculosis drugs between these two species, especially for the prodrugs ethionamide and isoniazid. In this study, we aimed to improve M. marinum as a model for antituberculosis drug identification by heterologous expression of two common drug activators, EthA and KatG. These two activators were overexpressed in M. marinum, and the strains were tested against ethionamide, isoniazid, and a library of established antimycobacterial compounds from TB Alliance to compare drug susceptibility. Both in vitro and in vivo using zebrafish larvae, these genetically modified M. marinum strains showed significantly higher susceptibility against ethionamide and isoniazid, which require activation by EthA and KatG. More importantly, a strain overexpressing both ethA and katG was potentially more susceptible to approximately 20% of the antituberculosis hit compounds from the TB Alliance library. Most of these compounds were activated by EthA in M. marinum Four of these compounds were selected for further analysis, and three of them showed obvious EthA-dependent activity against M. tuberculosis Overall, our developed M. marinum strains are valuable tools for high-throughput discovery of potential novel antituberculosis prodrugs.
| S-EPMC8097478 | biostudies-literature
Project description:Screening of 127 isoniazid (INH)-resistant Mycobacterium tuberculosis isolates from Singapore for mutations within the dfrA and inhA genes revealed mutations in 0 and 5 (3.9%) isolates respectively, implying that mutations in dfrA do not contribute to the detection of INH-resistant M. tuberculosis and that mutations within inhA are rare. Thirty-seven (29%) of the 127 isolates had no mutations in any of the genes implicated in INH resistance (katG, kasA, and ndh; inhA and ahpC promoters), suggesting that there are new INH targets yet to be discovered.
| S-EPMC2737874 | biostudies-literature
Project description:Tuberculosis (TB) is a global threat due to the emergence and spread of drug-resistant Mycobacterium tuberculosis (MTB). Isoniazid (INH) is the main antibiotic used for prevention and treatment of TB. Evidence shows that accumulated mutations can produce INH resistant (INHR) strains, resulting in the progression of multidrug-resistant (MDR) TB. Since point mutations in katG gene, inhA gene, and oxyR-ahpC region correlated with the INH resistance, in this study, we aimed to identify mutations in these three genes in INHR and MDR clinical isolates of MTB by Sanger DNA sequencing analysis. Thirty-three out of 438 isolates were resistant, including 66.7% INHR and 30.3% MDR isolates. In the katG gene, 68.2% INHR isolates had non-synonymous point mutations, mainly R463L (63.6%), and non-synonymous point mutation KatG L587P was seen in one of the MDR isolate. A novel silent substitution L649L was identified in the inhA gene of the MDR isolates. The oxyR-ahpC intergenic region g-88a common mutations (63.6%) in INHR and two distinct novel mutations were found at positions -76 and -77 of the oxyR-ahpC intergenic region. The coexistence of katG non-codon 315 with oxyR-ahpC intergenic region mutations was highly frequent in INHR 59.1% and MDR isolates 70%. Since mutations of all three genes 95.5% lead to the detection of INHR, they might be useful for molecular detection. Our results indicated the continuous evolution and region-specific prevalence of INH resistance. Overall, identification of new mutations in INH resistance can improve the available strategies for diagnosis and control of TB.
| S-EPMC8812758 | biostudies-literature
Project description:In this study, a battery of oligonucleotides was directed toward the katG gene and PCR-single-stranded conformation polymorphism (SSCP) analysis was used to search for katG gene deviations in clinical isolates of Mycobacterium tuberculosis from different geographical regions. Since a complete deletion of the katG gene was not found, it is suggested that deletion is not a major mechanism of isoniazid (isonicotinic acid hydrazide; INH) resistance in these isolates. However, 7 of 39 isolates (4 of 25 from South Africa and 3 of 14 from other geographical regions) showed mobility shifts by SSCP analysis, suggesting aberrations in the katG gene. Direct sequence analysis confirmed that the mobility shifts were due to Thr-275-->Ala (Thr275Ala), Arg409Ala, Arg463Leu, and Asp695Ala mutations and a 12-bp deletion in the 5' region of the katG gene. Mutations at codons 275, 463, and 695 created altered restriction sites for HhaI, MspI, and HaeIII, respectively, and sequence results, supported by restriction fragment length polymorphism analysis, suggested that the PCR-SSCP procedure is a good indicator of mutations in PCR-amplified fragments. Identical mutations at codons 463 and 275 were found in isolates from different geographical regions. This may suggest a common evolutionary event, but one of the control isolates (susceptible to INH [3%; n = 30]) also had a mutation at codon 463. The results suggest that variations in the katG coding gene sequences of INH-resistant isolates of M. tuberculosis are infrequent and that defects in other regions of the M. tuberculosis genome are of equal or greater importance in contributing to the acquisition of resistance to INH.
| S-EPMC162929 | biostudies-other
Project description:We report the discovery and confirmation of 23 novel mutations with previously undocumented role in isoniazid (INH) drug resistance, in catalase-peroxidase (katG) gene of Mycobacterium tuberculosis (Mtb) isolates. With these mutations, a synonymous mutation in fabG1 (g609a), and two canonical mutations, we were able to explain 98% of the phenotypic resistance observed in 366 clinical Mtb isolates collected from four high tuberculosis (TB)-burden countries: India, Moldova, Philippines, and South Africa. We conducted overlapping targeted and whole-genome sequencing for variant discovery in all clinical isolates with a variety of INH-resistant phenotypes. Our analysis showed that just two canonical mutations (katG 315AGC-ACC and inhA promoter-15C-T) identified 89.5% of resistance phenotypes in our collection. Inclusion of the 23 novel mutations reported here, and the previously documented point mutation in fabG1, increased the sensitivity of these mutations as markers of INH resistance to 98%. Only six (2%) of the 332 resistant isolates in our collection did not harbor one or more of these mutations. The third most prevalent substitution, at inhA promoter position -8, present in 39 resistant isolates, was of no diagnostic significance since it always co-occurred with katG 315. 79% of our isolates harboring novel mutations belong to genetic group 1 indicating a higher tendency for this group to go down an uncommon evolutionary path and evade molecular diagnostics. The results of this study contribute to our understanding of the mechanisms of INH resistance in Mtb isolates that lack the canonical mutations and could improve the sensitivity of next generation molecular diagnostics.
| S-EPMC4522615 | biostudies-literature
Project description:Isoniazid (INH) is an effective first-line antituberculosis drug. KatG, a catalase-peroxidase, converts INH to an active form in Mycobacterium tuberculosis, and katG mutations are major causes of INH resistance. In the present study, we sequenced katG of 108 INH-resistant M. tuberculosis clinical isolates. Consequently, 9 novel KatG mutants with a single-amino-acid substitution were found. All of these mutants had significantly lower INH oxidase activities than the wild type, and each mutant showed various levels of activity. Isolates having mutations with relatively low activities showed high-level INH resistance. On the basis of our results and known mutations associated with INH resistance, we developed a new hybridization-based line probe assay for rapid detection of INH-resistant M. tuberculosis isolates.
| S-EPMC2863633 | biostudies-literature
Project description:Whole-genome sequencing was used to analyze the profiles of isoniazid (INH) resistance-related mutations among 188 multidrug-resistant strains of Mycobacterium tuberculosis (MDR-TB) and mono-INH-resistant isolates collected in a recent Chinese national survey. Mutations were detected in 18 structural genes and two promoter regions in 96.8% of 188 resistant isolates. There were high mutation frequencies in katG, the inhA promoter, and ahpC-oxyR regulator regions in INH-resistant isolates with frequencies of 86.2%, 19.6%, and 18.6%, respectively. Moreover, a high diversity of mutations was identified as 102 mutants contained various types of single or combined gene mutations in the INH-resistant group of isolates. The cumulative frequencies of katG 315 or inhA-P/inhA mutations was 68.1% (128/188) for the INH-resistant isolates. Of these isolates, 46 isolates (24.5% of 188) exhibited a high level of resistance. A high level of resistance was also observed in 21 isolates (11.2% of 188) with single ahpC-oxyR mutations or a combination of ahpC-oxyR and katG non-315 mutations. The remaining 17 mutations occurred sporadically and emerged in isolates with combined katG mutations. Such development of INH resistance is likely due to an accumulation of mutations under the pressure of drug selection. Thus, these findings provided insights on the levels of INH resistance and its correlation with the combinatorial mutation effect resulting from less frequent genes (inhA and/or ahpC). Such knowledge of other genes (apart from katG) in high-level resistance will aid in developing better strategies for the diagnosis and management of TB.
| S-EPMC6240042 | biostudies-literature
Project description:Tuberculosis (TB), an infectious disease caused by Mycobacterium tuberculosis, is among the top 10 leading causes of death worldwide. The treatment course for TB is challenging; it requires antibiotic administration for at least 6 months, and bacterial drug resistance makes treatment even more difficult. Understanding the mechanisms of resistance is important for improving treatment. To investigate new mechanisms of isoniazid (INH) resistance, we obtained three INH-resistant (INH-R) M. tuberculosis clinical isolates collected by the Taiwan Centers for Disease Control (TCDC) and sequenced genes known to harbor INH resistance-conferring mutations. Then, the relationship between the mutations and INH resistance of these three INH-R isolates was investigated. Sequencing of the INH-R isolates identified three novel katG mutations resulting in R146P, W341R, and L398P KatG proteins, respectively. To investigate the correlation between the observed INH-R phenotypes of the clinical isolates and these katG mutations, wild-type katG from H37Rv was expressed on a plasmid (pMN437-katG) in the isolates, and their susceptibilities to INH were determined. The plasmid expressing H37Rv katG restored INH susceptibility in the two INH-R isolates encoding the W341R KatG and L398P KatG proteins. In contrast, no phenotypic change was observed in the KatG R146P isolate harboring pMN437-katG. H37Rv isogenic mutant with W341R KatG or L398P KatG was further generated. Both showed resistant to INH. In conclusion, W341R KatG and L398P KatG conferred resistance to INH in M. tuberculosis, whereas R146P KatG did not affect the INH susceptibility of M. tuberculosis.
| S-EPMC7374161 | biostudies-literature