scholarly journals Isoniazid-resistant Mycobacterium tuberculosis: prevalence, resistance spectrum and genetic determinants of resistance

2020 ◽  
pp. 21-26
Author(s):  
S.N. Andreevskaya ◽  
T.G. Smirnova ◽  
E.E. Larionova ◽  
I.Yu. Andrievskaya ◽  
L.N. Chernousova ◽  
...  
Keyword(s):  
Molecular Genetic ◽  
Drug Susceptibility ◽  
Literature Analysis ◽  
Genetic Determinants ◽  
Katg Gene ◽  
Isoniazid Resistance ◽  
Susceptibility Tests ◽  
Resistance Spectrum ◽  
Tuberculosis Prevalence ◽  
Phenotypic Susceptibility

The lack of simple, rapid diagnostic tests for isoniazid-resistant rifampicin-susceptible tuberculosis infection (Hr-TB) can result in low treatment efficacy and further amplification of drug resistance. Based on the clinical data, this study sought to estimate the prevalence of Hr-TB in the general population and characterize the phenotypic susceptibility and genetic determinants of isoniazid resistance in M. tuberculosis strains. Molecular-genetic and culture-based drug susceptibility tests were performed on M. tuberculosis isolates and M. tuberculosis DNA obtained from the patients with pulmonary TB undergoing treatment at the Central Tuberculosis Research Institute between 2011 and 2018. The tests revealed that Hr-TB accounted for 12% of all TB cases in the studied sample. Hr-TB strains were either resistant to isoniazid only (45%) or had multiple resistance to 2–6 anti-TB agents. Resistance to isoniazid was caused by mutations in the katG gene. Based on the literature analysis and our own observations, we emphasize the importance of developing simple molecular drug susceptibility tests capable of detecting simultaneous resistance to rifampicin and isoniazid and the necessity of their translation into clinical practice.

scholarly journals Whole-Genome Sequencing to Identify Missed Rifampicin and Isoniazid Resistance Among Tuberculosis Isolates—Chennai, India, 2013–2016

2021 ◽  
Vol 12 ◽  
Author(s):  
Sembulingam Tamilzhalagan ◽  
Sivakumar Shanmugam ◽  
Ashok Selvaraj ◽  
Sakthi Suba ◽  
Chittibabu Suganthi ◽  
...  
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Drug Susceptibility ◽  
Clinical Diagnostics ◽  
Whole Genome ◽  
Isoniazid Resistance ◽  
Resistant Tuberculosis ◽  
Lowenstein Jensen ◽  
Susceptibility Tests ◽  
Level Resistance

India has a high burden of drug-resistant tuberculosis (DR TB) and many cases go undetected by current drug susceptibility tests (DSTs). This study was conducted to identify rifampicin (RIF) and isoniazid (INH) resistance associated genetic mutations undetected by current clinical diagnostics amongst persons with DR TB in Chennai, India. Retrospectively stored 166 DR TB isolates during 2013–2016 were retrieved and cultured in Löwenstein-Jensen medium. Whole genome sequencing (WGS) and MGIT DST for RIF and INH were performed. Discordant genotypic and phenotypic sensitivity results were repeated for confirmation and the discrepant results considered final. Further, drug resistance-conferring mutations identified through WGS were analyzed for their presence as targets in current WHO-recommended molecular diagnostics. WGS detected additional mutations for rifampicin and isoniazid resistance than WHO-endorsed line probe assays. For RIF, WGS was able to identify an additional 10% (15/146) of rpoB mutant isolates associated with borderline rifampicin resistance compared to MGIT DST. WGS could detect additional DR TB cases than commercially available and WHO-endorsed molecular DST tests. WGS results reiterate the importance of the recent WHO revised critical concentrations of current MGIT DST to detect low-level resistance to rifampicin. WGS may help inform effective treatment selection for persons at risk of, or diagnosed with, DR TB.

scholarly journals Recurrent candidaemia in a neonate with Hirschsprung's disease: fluconazole resistance and genetic relatedness of eight Candida tropicalis isolates

2006 ◽  
Vol 55 (4) ◽  
pp. 423-428 ◽  
Author(s):  
Pei Pei Chong ◽  
David Ching-Soo Chieng ◽  
Lee Yean Low ◽  
Asma Hafeez ◽  
Mariana Nor Shamsudin ◽  
...  
Keyword(s):  
Candida Tropicalis ◽  
Hirschsprung's Disease ◽  
Hirschsprung’S Disease ◽  
Genetic Relatedness ◽  
Infectious Agent ◽  
Venous Catheter ◽  
Drug Susceptibility ◽  
Fluconazole Resistant ◽  
Susceptibility Tests

The incidence of candidaemia among immunocompromised patients in Malaysia is increasing at an alarming rate. Isolation of clinical strains that are resistant to fluconazole has also risen markedly. We report here the repeated isolation of Candida tropicalis from the blood of a neonatal patient with Hirschsprung's disease. In vitro fluconazole susceptibility tests of the eight isolates obtained at different time points showed that seven of the isolates were resistant and one isolate was scored as susceptible dose-dependent. Random amplification of polymorphic DNA fingerprinting of the isolates using three primers and subsequent phylogenetic analysis revealed that these isolates were highly similar strains having minor genetic divergence, with a mean pairwise similarity coefficient of 0·893±0·041. The source of the infectious agent was thought to be the central venous catheter, as culture of its tip produced fluconazole-resistant C. tropicalis. This study demonstrates the utility of applying molecular epidemiology techniques to complement traditional mycological culture and drug susceptibility tests for accurate and appropriate management of recurrent candidaemia and highlights the need for newer antifungals that can combat the emergence of fluconazole-resistant C. tropicalis strains.

scholarly journals Quantitative measurement of antibiotic resistance in Mycobacterium tuberculosis reveals genetic determinants of resistance and susceptibility in a target gene approach

2021 ◽  
Author(s):  
◽  
Joshua J Carter
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Quantitative Measurement ◽  
Target Gene ◽  
Microtiter Plate ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
World Health ◽  
Genetic Determinants ◽  
Microtiter Plate Assay ◽  
Health Organization

AbstractThe World Health Organization goal of universal drug susceptibility testing for patients with tuberculosis is most likely to be achieved through molecular diagnostics; however, to date these have focused largely on first-line drugs, and always on predicting binary susceptibilities. Here, we used whole genome sequencing and a quantitative microtiter plate assay to relate genomic mutations to minimum inhibitory concentration in 15,211 Mycobacterium tuberculosis patient isolates from 27 countries across five continents.This work identifies 449 unique MIC-elevating genetic determinants across thirteen drugs, as well as 91 mutations resulting in hypersensitivity for eleven drugs. Our results provide a guide for further implementation of personalized medicine for the treatment of tuberculosis using genetics-based diagnostics and can serve as a training set for novel approaches to predict drug resistance.

scholarly journals MOLECULAR GENETIC DETERMINANTS OF LONG-TERM SURVIVAL WITH GLIOBLASTOMA

2014 ◽  
Vol 16 (suppl 3) ◽  
pp. iii46-iii47
Author(s):  
M. Weller ◽  
R. G. Weber ◽  
V. Riehmer ◽  
K. Kaulich ◽  
E. Willscher ◽  
...  
Keyword(s):  
Molecular Genetic ◽  
Genetic Determinants ◽  
Term Survival ◽  
Long Term Survival

scholarly journals Molecular Analysis of Codon 548 in therpoBGene Involved in Mycobacterium tuberculosis Resistance to Rifampin

2014 ◽  
Vol 59 (3) ◽  
pp. 1542-1548 ◽  
Author(s):  
Yu-Tze Horng ◽  
Wen-Yih Jeng ◽  
Yih-Yuan Chen ◽  
Che-Hung Liu ◽  
Horng-Yunn Dou ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Bacterial Resistance ◽  
Drug Susceptibility ◽  
Content Type ◽  
Stable Hydrogen Bond ◽  
Resistance Patterns ◽  
Resistant Strains ◽  
Rifampin Resistance ◽  
Susceptibility Tests ◽  
Dna Complex

ABSTRACTMostMycobacterium tuberculosisrifampin-resistant strains have been associated with mutations in an 81-bp rifampin resistance-determining region (RRDR) in the generpoB. However, if this region alone were targeted, rifampin-resistant strains with mutations outside the RRDR would not be detected. In this study, among 51 rifampin-resistant clinical isolates analyzed by sequencing 1,681-bp-long DNA fragments containing the RRDR, 47 isolates contained mutations within the RRDR, three isolates contained mutations both within and outside the RRDR, and only one isolate had a single missense mutation (Arg548His) located outside the RRDR. A drug susceptibility test of recombinantMycobacterium smegmatisandM. tuberculosisisolates carrying mutatedrpoB(Arg548His) showed an increased MIC for rifampin compared to that of the control strains. Modeling of the Arg548His mutant RpoB-DNA complex revealed that the His548 side chain formed a more stable hydrogen bond structure than did Arg548, reducing the flexibility of the rifampin-resistant cluster II region of RpoB, suggesting that the RpoB Arg548His mutant does not effectively interact with rifampin and results in bacterial resistance to the drug. This is the first report on the relationship between the mutation in codon 548 of RpoB and rifampin resistance in tuberculosis. The novel mutational profile of therpoBgene described here will contribute to the comprehensive understanding of rifampin resistance patterns and to the development of a useful tool for simple and rapid drug susceptibility tests.

scholarly journals Molecular characterisation of multidrug-resistantMycobacterium tuberculosisisolates from a high-burden tuberculosis state in Brazil

2019 ◽  
Vol 147 ◽  
Author(s):  
R. S. Salvato ◽  
S. Schiefelbein ◽  
R. B. Barcellos ◽  
B. M. Praetzel ◽  
I. S. Anusca ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Drug Susceptibility Testing ◽  
Molecular Characterisation ◽  
Drug Resistant ◽  
Isoniazid Resistance ◽  
High Burden ◽  
Brics Countries ◽  
Mdr Tb

AbstractTuberculosis (TB) is the leading cause of death among infectious diseases worldwide. Among the estimated cases of drug-resistant TB, approximately 60% occur in the BRICS countries (Brazil, Russia, India, China and South Africa). Among Brazilian states, primary and acquired multidrug-resistant TB (MDR-TB) rates were the highest in Rio Grande do Sul (RS). This study aimed to perform molecular characterisation of MDR-TB in the State of RS, a high-burden Brazilian state. We performed molecular characterisation of MDR-TB cases in RS, defined by drug susceptibility testing, using 131Mycobacterium tuberculosis (M.tb)DNA samples from the Central Laboratory. We carried out MIRU-VNTR 24loci, spoligotyping, sequencing of thekatG,inhA andrpoB genes and RDRiosublineage identification. The most frequent families found were LAM (65.6%) and Haarlem (22.1%). RDRiodeletion was observed in 42 (32%) of theM.tbisolates. Among MDR-TB cases, eight (6.1%) did not present mutations in the studied genes. In 116 (88.5%)M.tbisolates, we found mutations associated with rifampicin (RIF) resistance inrpoB gene, and in 112 isolates (85.5%), we observed mutations related to isoniazid resistance inkatG andinhA genes. An insertion of 12 nucleotides (CCAGAACAACCC) at the 516 codon in therpoB gene, possibly responsible for a decreased interaction of RIF and RNA polymerase, was found in 19/131 of the isolates, belonging mostly to LAM and Haarlem families. These results enable a better understanding of the dynamics of transmission and evolution of MDR-TB in the region.

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