In Silico Analysis of S315T and S315R Mutations of Multidrug-resistant Mycobacterium tuberculosis Clinical Isolates from Karachi, Pakistan

2020 ◽  
Vol 13 (9) ◽  
Author(s):  
Muhammad Mumtaz Khan ◽  
Maria S Alves ◽  
Sadia Alam ◽  
Mohammad H Khan ◽  
Muhammad Jahangir ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistance ◽  
Conformational Changes ◽  
Gene Mutations ◽  
In Silico Analysis ◽  
Multidrug Resistant ◽  
Electrostatic Energy ◽  
Katg Gene ◽  
Resistant Strains ◽  
Binding Residues

Background: Tuberculosis is one of the most frequent and persistent global diseases causing millions of deaths every year. Pakistan lies at number 6 among the 22 most dominant countries, with multidrug resistance up to 15%. Isoniazid-resistant strains of Mycobacterium tuberculosis are gradually rising and seem to be more prevalent in developing countries. Mutations in the katG gene are considered to be responsible for the accusation of isoniazid resistance in M. tuberculosis. Objectives: The current study was designed to investigate the structural and functional associations of KatG gene mutations (S315R and S315T) and multidrug resistance in M. tuberculosis isolates from Karachi, Pakistan. Results: The present study revealed conformational changes in the structure of the KatG enzyme due to observed mutations, which led to induced alterations in isoniazid binding residues at the active site of the KatG enzyme. Furthermore, substantial changes were observed in interaction energy, ligand-receptor energy, electrostatic energy, salvation energy, and ligand-receptor conformational entropy. All these resultant modifications due to S315R and S315T mutations ultimately reduced the flexibility and stability of proteins at isoniazid-binding residues. Conclusions: This deviation in the consistency of protein texture eventually compromises the enzyme activity. It is well expected that the outcomes of the current study would provide a better understanding of the consequences of these mutations and provide a detailed insight into some previously unknown features.

scholarly journals Constraints of Drug Resistance in Mycobacterium tuberculosis - Prospects for Pharmacological Reversion of Susceptibility to Antibiotics

2017 ◽  
Vol 8 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Aleksandr I. Ilin ◽  
Murat E. Kulmanov ◽  
Ilya S. Korotetskiy ◽  
Marina V. Lankina ◽  
Gulshara K. Akhmetova ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Genetic Heterogeneity ◽  
Multidrug Resistant ◽  
Resistance Mutations ◽  
General Increase ◽  
Drug Induced ◽  
Mdr Tb ◽  
Resistant Strains

Emergence of multidrug resistant strains ofMycobacterium tuberculosis(MDR-TB) threatens humanity. This problem was complicated by the crisis in development of new anti-tuberculosis antibiotics. Induced reversion of drug resistance seems promising to overcome the problem. Successful clinical trial of a new anti-tuberculosis nanomolecular complex FS-1 has demonstrated prospectively of this approach in combating MDR-TB. Several clinical MDR-TB cultures were isolated from sputum samples prior and in the process of the clinical trial. Every isolate was tested for susceptibility to antibiotics and then they were sequenced for comparative genomics. It was found that the treatment with FS-1 caused an increase in the number of antibiotic susceptible strains among Mtb isolates that was associated with a general increase of genetic heterogeneity of the isolates. Observed impairing of phthiocerol dimycocerosate biosynthesis by disruptive mutations inppsACDsubunits indicated a possible virulence remission for the sake of persistence. It was hypothesized that the FS-1 treatment eradicated the most drug resistant Mtb variants from the population by aggravating the fitness cost of drug resistance mutations. Analysis of distribution of these mutations in the global Mtb population revealed that many of them were incompatible with each other and dependent on allelic states of many other polymorphic loci. The latter discovery may explain the negative correlation between the genetic heterogeneity of the population and the level of drug tolerance. To the best of our knowledge, this work was the first experimental confirmation of the drug induced antibiotic resistance reversion by the induced synergy mechanism that previously was predicted theoretically.

scholarly journals Direct Detection of Pyrazinamide Resistance in Mycobacterium tuberculosis by Use of pncA PCR Sequencing

2019 ◽  
Vol 57 (8) ◽  
Author(s):  
Kingsley King-Gee Tam ◽  
Kenneth Siu-Sing Leung ◽  
Gilman Kit-Hang Siu ◽  
Kwok-Chiu Chang ◽  
Samson Sai-Yin Wong ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Direct Detection ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Activity Data ◽  
Content Type ◽  
Treatment Regimens ◽  
Mdr Tb ◽  
Resistant Strains ◽  
Respiratory Specimens

ABSTRACT An in-house-developed pncA sequencing assay for analysis of pyrazinamide (PZA) resistance was evaluated using 162 archived Mycobacterium tuberculosis complex (MTBC) isolates with phenotypic PZA susceptibility profiles that were well defined by analysis of Bactec MGIT 960 PZA kit and PZase activity data. Preliminary results showed 100% concordance between pncA sequencing and phenotypic PZA drug susceptibility test (DST) results among archived isolates. Also, 637 respiratory specimens were prospectively collected, and 158 were reported as MTBC positive by the Abbott Realtime MTB assay (96.3% sensitivity [95% confidence interval {CI}: 92.2% to 98.7%]; 100% specificity [95% CI: 99.2% to 100.0%]). Genotypic and phenotypic PZA resistance profiles of these 158 MTBC-positive specimens were analyzed by pncA sequencing and Bactec MGIT 960 PZA kit, respectively. For analysis of PZA resistance, pncA sequencing detected pncA mutations in 5/5 (100%) phenotypic PZA-resistant respiratory specimens within 4 working days. No pncA mutations were detected among PZA-susceptible specimens. Combining archived isolates with prospective specimens, 27 were identified as phenotypic PZA resistant with pncA mutation. Among these 27 samples, 6/27 (22.2%) phenotypic PZA-resistant strains carried novel pncA mutations without rpsA and panD mutations. These included 5 with mutations (a deletion [Del] at 383T [Del383T], Del 380 to 390, insertion of A [A Ins] at position 127, A Ins at position 407, and G Ins at position 508) in pncA structural genes and 1 with a mutation (T-12C) at the pncA promoter region. All six of these strains had no or reduced PZase activities, indicating that the novel mutations might confer PZA resistance. Additionally, 25/27 phenotypic PZA-resistant strains were confirmed multidrug-resistant tuberculosis (MDR-TB) strains. As PZA is commonly used in MDR-TB treatment regimens, direct pncA sequencing will rapidly detect PZA resistance and facilitate judicious use of PZA in treating PZA-susceptible MDR-TB.

scholarly journals Fluoroquinolone Resistance amongMycobacterium tuberculosisStrains from Karachi, Pakistan: Data from Community-Based Field Clinics

2010 ◽  
Vol 55 (2) ◽  
pp. 929-930 ◽  
Author(s):  
Yasraba Rafiq ◽  
Kauser Jabeen ◽  
Rumina Hasan ◽  
Sana Jafri ◽  
Rabia Laiq ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
Resistance Rate ◽  
Fluoroquinolone Resistance ◽  
First Line ◽  
Sensitivity Testing ◽  
Community Based ◽  
Strain Type ◽  
Resistant Strains

ABSTRACTA fluoroquinolone (FQ) resistance rate of 5.9% is reported in 205Mycobacterium tuberculosisisolates from patients presenting to field clinics in Karachi, Pakistan (2006 to 2009). FQ resistance among multidrug-resistant (MDR) strains was 11.1% (5/45), and it was 4.9% (5/103) inM. tuberculosisstrains susceptible to all first-line agents. Spoligotyping of resistant strains did not show dominance of one strain type. Our data reflect considerable FQ-resistantM. tuberculosisisolates and the need to consider inclusion of FQ within first-line sensitivity testing in such settings.

scholarly journals Direct detection of rpoB and katG gene mutations of Mycobacterium tuberculosis in clinical samples

2017 ◽  
Vol 7 (8) ◽  
pp. 698-701
Author(s):  
Sunil Pandey ◽  
Ashima Lamichhane ◽  
Anu Byanjankar ◽  
Ansuma Kharel ◽  
Chandrakala Rai ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Direct Detection ◽  
Gene Mutations ◽  
Clinical Samples ◽  
Katg Gene

scholarly journals In Vitro Activity and MIC of Sitafloxacin against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis Isolated in Thailand

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Manoon Leechawengwongs ◽  
Therdsak Prammananan ◽  
Sarinya Jaitrong ◽  
Pamaree Billamas ◽  
Nampueng Makhao ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Critical Concentration ◽  
Multidrug Resistant ◽  
Quinolone Resistance ◽  
Drug Resistant ◽  
Content Type ◽  
Extensively Drug Resistant ◽  
Resistant Strains ◽  
Drug Resistant Strains

ABSTRACT New fluoroquinolones (FQs) have been shown to be more active against drug-resistant Mycobacterium tuberculosis strains than early FQs, such as ofloxacin. Sitafloxacin (STFX) is a new fluoroquinolone with in vitro activity against a broad range of bacteria, including M. tuberculosis. This study aimed to determine the in vitro activity of STFX against all groups of drug-resistant strains, including multidrug-resistant M. tuberculosis (MDR M. tuberculosis), MDR M. tuberculosis with quinolone resistance (pre-XDR), and extensively drug-resistant (XDR) strains. A total of 374 drug-resistant M. tuberculosis strains were tested for drug susceptibility by the conventional proportion method, and 95 strains were randomly submitted for MIC determination using the microplate alamarBlue assay (MABA). The results revealed that all the drug-resistant strains were susceptible to STFX at a critical concentration of 2 μg/ml. Determination of the MIC90s of the strains showed different MIC levels; MDR M. tuberculosis strains had a MIC90 of 0.0625 μg/ml, whereas pre-XDR and XDR M. tuberculosis strains had identical MIC90s of 0.5 μg/ml. Common mutations within the quinolone resistance-determining region (QRDR) of gyrA and/or gyrB did not confer resistance to STFX, except that double mutations of GyrA at Ala90Val and Asp94Ala were found in strains with a MIC of 1.0 μg/ml. The results indicated that STFX had potent in vitro activity against all the groups of drug-resistant M. tuberculosis strains and should be considered a new repurposed drug for treatment of multidrug-resistant and extensively drug-resistant TB.

Characterization of the Mycobacterium tuberculosis H37Rv alkyl hydroperoxidase AhpC points to the importance of ionic interactions in oligomerization and activity

2001 ◽  
Vol 354 (1) ◽  
pp. 209-215 ◽  
Author(s):  
Radha CHAUHAN ◽  
Shekhar C. MANDE
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Conformational Changes ◽  
Three Dimensional ◽  
Enteric Bacteria ◽  
Enzymic Activity ◽  
Ionic Interactions ◽  
Three Dimensional Model ◽  
Mycobacterium Tuberculosis H37rv ◽  
Resistant Strains ◽  
Alkyl Hydroperoxidase

An alkyl hydroperoxidase (AhpC) has been found frequently to be overexpressed in isoniazid-resistant strains of Mycobacterium tuberculosis. These strains have an inactivated katG gene encoding a catalase peroxidase, which might render mycobacteria susceptible to the toxic peroxide radicals, thus leading to the concomitant overexpression of the AhpC. Although the overexpressed AhpC in isoniazid-resistant strains of M. tuberculosis may not directly participate in isoniazid action, AhpC might still assist M. tuberculosis in combating oxidative damage in the absence of the catalase. Here we have attempted to characterize the AhpC protein biochemically and report its functional and oligomerization properties. The alkyl hydroperoxidase of M. tuberculosis is unique in many ways compared with its well-characterized homologues from enteric bacteria. We show that AhpC is a decameric protein, composed of five identical dimers held together by ionic interactions. Dimerization of individual subunits takes place through an intersubunit disulphide linkage. The ionic interactions play a significant role in enzymic activity of the AhpC protein. The UV absorption spectrum and three-dimensional model of AhpC suggest that interesting conformational changes may take place during oxidation and reduction of the intersubunit disulphide linkage. In the absence of the partner AhpF subunit in M. tuberculosis, the mycobacterial AhpC might use small-molecule reagents, such as mycothiol, for completing its enzymic cycle.

Sign in / Sign up

Export Citation Format

Share Document