Time-kill kinetics of anti-tuberculosis drugs, and emergence of resistance, in relation to metabolic activity of Mycobacterium tuberculosis

Scientific interest in mycobacteria has been sparked by the medical importance of Mycobacterium tuberculosis (Mtb) that is known to cause severe diseases in mammals, i.e. tuberculosis and by properties that distinguish them from other microorganisms which are notoriously difficult to treat. The treatment of their infections is difficult because mycobacteria fortify themselves with a thick impermeable cell envelope. Channel and transporter proteins are among the crucial adaptations of Mycobacterium that facilitate their strength to combat against host immune system and anti-tuberculosis drugs. In previous studies, it was investigated that some of the channel proteins contribute to the overall antibiotic resistance in Mtb. Moreover, in some of the cases, membrane proteins were found responsible for virulence of these pathogens. Given the ability of M. tuberculosis to survive as an intracellular pathogen and its inclination to develop resistance to the prevailing anti-tuberculosis drugs, its treatment requires new approaches and optimization of anti-TB drugs and investigation of new targets are needed for their potential in clinical usage. Therefore, it is imperative to investigate the survival of Mtb. in stressed conditions with different behavior of particular channel/ transporter proteins. Comprehensive understanding of channel proteins and their mechanism will provide us direction to find out preventive measures against the emergence of resistance and reduce the duration of the treatment, eventually leading to plausible eradication of tuberculosis.

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Bactericidal Activity, Absence of Serum Effect, and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02894-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5297-5305 ◽

Cited By ~ 55

Author(s):

Tiffany R. Keepers ◽

Marcela Gomez ◽

Chris Celeri ◽

Wright W. Nichols ◽

Kevin M. Krause

Keyword(s):

Pseudomonas Aeruginosa ◽

Human Serum ◽

Bactericidal Activity ◽

Minimum Bactericidal Concentration ◽

Wild Type ◽

Content Type ◽

Positive Isolate ◽

New Treatment ◽

Time Kill ◽

Kinetics Of

ABSTRACTAvibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18Pseudomonas aeruginosaisolates and 15Enterobacteriaceaeisolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2P. aeruginosaisolates (1blaVIM-positive isolate and 1blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10decrease in the number of CFU/ml was observed at 6 h for allEnterobacteriaceae, and a 2-log10reduction in the number of CFU/ml was observed at 6 h for 3 of the 6P. aeruginosaisolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused byEnterobacteriaceaeandP. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.

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Kinetics of Mycobacterium tuberculosis-specific IFN-γ responses and sputum bacillary clearance in HIV-infected adults during treatment of pulmonary tuberculosis

Tuberculosis ◽

10.1016/j.tube.2015.05.009 ◽

2015 ◽

Vol 95 (4) ◽

pp. 463-469

Author(s):

David T. Mzinza ◽

Derek J. Sloan ◽

Kondwani C. Jambo ◽

Doris Shani ◽

Mercy Kamdolozi ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Pulmonary Tuberculosis ◽

Ifn Γ ◽

Kinetics Of

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Characterization of the Two Mycobacterium tuberculosis recA Promoters

Journal of Bacteriology ◽

10.1128/jb.185.20.6005-6015.2003 ◽

2003 ◽

Vol 185 (20) ◽

pp. 6005-6015 ◽

Cited By ~ 21

Author(s):

Krishna K. Gopaul ◽

Patricia C. Brooks ◽

Jean-François Prost ◽

Elaine O. Davis

Keyword(s):

Escherichia Coli ◽

Dna Damage ◽

Mycobacterium Tuberculosis ◽

Promoter Activity ◽

The Other ◽

Expression Level ◽

Promoter Elements ◽

Kinetics Of

ABSTRACT The recA gene of Mycobacterium tuberculosis is unusual in that it is expressed from two promoters, one of which, P1, is DNA damage inducible independently of LexA and RecA, while the other, P2, is regulated by LexA in the classical way (E. O. Davis, B. Springer, K. K. Gopaul, K. G. Papavinasasundaram, P. Sander, and E. C. Böttger, Mol. Microbiol. 46:791-800, 2002). In this study we characterized these two promoters in more detail. Firstly, we localized the promoter elements for each of the promoters, and in so doing we identified a mutation in each promoter which eliminates promoter activity. Interestingly, a motif with similarity to Escherichia coli σ70 −35 elements but located much closer to the −10 element is important for optimal expression of P1, whereas the sequence at the −35 location is not. Secondly, we found that the sequences flanking the promoters can have a profound effect on the expression level directed by each of the promoters. Finally, we examined the contribution of each of the promoters to recA expression and compared their kinetics of induction following DNA damage.

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Real-time kinetic studies of Mycobacterium tuberculosis LexA-DNA interaction

Bioscience Reports ◽

10.1042/bcj20210434 ◽

2021 ◽

Author(s):

Chitral Chatterjee ◽

Soneya Majumdar ◽

Sachin Deshpande ◽

Deepak Pant ◽

Saravanan Matheshwaran

Keyword(s):

Amino Acids ◽

Mycobacterium Tuberculosis ◽

Dna Binding ◽

Kinetic Parameters ◽

Dna Sequences ◽

Kinetic Studies ◽

Dna Interaction ◽

Damage Repair ◽

Inducible Genes ◽

Kinetics Of

Transcriptional repressor, LexA, regulates the “SOS” response, an indispensable bacterial DNA damage repair machinery. Compared to its E.coli ortholog, LexA from Mycobacterium tuberculosis (Mtb) possesses a unique N-terminal extension of additional 24 amino acids in its DNA binding domain (DBD) and 18 amino acids insertion at its hinge region that connects the DBD to the C-terminal dimerization/autoproteolysis domain. Despite the importance of LexA in “SOS” regulation, Mtb LexA remains poorly characterized and the functional importance of its additional amino acids remained elusive. In addition, the lack of data on kinetic parameters of Mtb LexA-DNA interaction prompted us to perform kinetic analyses of Mtb LexA and its deletion variants using Bio-layer Interferometry (BLI). Mtb LexA is seen to bind to different “SOS” boxes, DNA sequences present in the operator regions of damage-inducible genes, with comparable nanomolar affinity. Deletion of 18 amino acids from the linker region is found to affect DNA binding unlike the deletion of the N-terminal stretch of extra 24 amino acids. The conserved RKG motif has been found to be critical for DNA binding. Overall, this study provides insights into the kinetics of the interaction between Mtb LexA and its target “SOS” boxes. The kinetic parameters obtained for DNA binding of Mtb LexA would be instrumental to clearly understand the mechanism of “SOS” regulation and activation in Mtb.

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Growth kinetics of Mycobacterium tuberculosis measured by quantitative resazurin reduction assay: a tool for fitness studies

Brazilian Journal of Microbiology ◽

10.1590/s1517-83822010000200006 ◽

2010 ◽

Vol 41 (2) ◽

pp. 300-303 ◽

Cited By ~ 10

Author(s):

Andrea von Groll ◽

Anandi Martin ◽

Françoise Portaels ◽

Pedro Eduardo Almeida da Silva ◽

Juan Carlos Palomino

Keyword(s):

Mycobacterium Tuberculosis ◽

Growth Kinetics ◽

Reduction Assay ◽

Kinetics Of

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Antimicrobial activity and time kill kinetics of Nigerian Honeys on multi-resistant Enteric Bacilli

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/210/1/012003 ◽

2018 ◽

Vol 210 ◽

pp. 012003

Author(s):

P.A Akinduti ◽

A Oluwadun ◽

J.A.O Olugbuyiro ◽

C.S Osuagwu ◽

O Ejilude ◽

...

Keyword(s):

Antimicrobial Activity ◽

Time Kill ◽

Kinetics Of

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Genotypic Analysis of Genes Associated with Independent Resistance and Cross-Resistance to Isoniazid and Ethionamide in Mycobacterium tuberculosis Clinical Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01028-15 ◽

2015 ◽

Vol 59 (12) ◽

pp. 7805-7810 ◽

Cited By ~ 25

Author(s):

Johana Rueda ◽

Teresa Realpe ◽

Gloria Isabel Mejia ◽

Elsa Zapata ◽

Juan Carlos Rozo ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Multidrug Resistant ◽

Cross Resistance ◽

Resistance Mutations ◽

Content Type ◽

Genotypic Analysis ◽

Mdr Tb ◽

Proportion Method ◽

Emergence Of Resistance ◽

Phenotypic Susceptibility

ABSTRACTEthionamide (ETH) is an antibiotic used for the treatment of multidrug-resistant (MDR) tuberculosis (TB) (MDR-TB), and its use may be limited with the emergence of resistance in theMycobacterium tuberculosispopulation. ETH resistance inM. tuberculosisis phenomenon independent or cross related when accompanied with isoniazid (INH) resistance. In most cases, resistance to INH and ETH is explained by mutations in theinhApromoter and in the following genes:katG,ethA,ethR,mshA,ndh, andinhA. We sequenced the above genes in 64M. tuberculosisisolates (n= 57 ETH-resistant MDR-TB isolates;n= 3 ETH-susceptible MDR-TB isolates; andn= 4 fully susceptible isolates). Each isolate was tested for susceptibility to first- and second-line drugs using the agar proportion method. Mutations were observed in ETH-resistant MDR-TB isolates at the following rates: 100% inkatG, 72% inethA, 45.6% inmshA, 8.7% inndh, and 33.3% ininhAor its promoter. Of the three ETH-susceptible MDR-TB isolates, all showed mutations inkatG; one had a mutation inethA, and another, inmshAandinhA. Finally, of the four fully susceptible isolates, two showed no detectable mutation in the studied genes, and two had mutations inmshAgene unrelated to the resistance. Mutations not previously reported were found in theethA,mshA,katG, andndhgenes. The concordance between the phenotypic susceptibility testing to INH and ETH and the sequencing was 1 and 0.45, respectively. Among isolates exhibiting INH resistance, the high frequency of independent resistance and cross-resistance with ETH in theM. tuberculosisisolates suggests the need to confirm the susceptibility to ETH before considering it in the treatment of patients with MDR-TB.

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