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Effect of efflux pump inhibitors on the susceptibility of Mycobacterium tuberculosis to isoniazid.

ABSTRACT: BACKGROUND:Mycobacterium can develop drug resistance (DR) by mutation of its existing gene. However, the existence of DR without mutation shows the need to look for an alternative mechanism such as the role of efflux pumps. In this study, we examined the effect of efflux pump inhibitors on isoniazid (INH) susceptibility in clinical isolates of Mycobacterium tuberculosis (Mtb). MATERIALS AND METHODS:Resazurin microtiter assay was used to examine the effect of efflux pump inhibitors on minimum inhibitory concentration (MIC) levels of INH in eighteen Mtb clinical isolates. RESULTS:The observed reduction in INH-MIC was 2-16-fold in INH-resistant isolates with katG and inhA gene mutations, 2-8-fold in INH-resistant isolates without mutation and 2-4-fold in INH-sensitive isolates. The MIC reduction by verapamil (VER) was observed in 83% isolates, by carbonyl cyanide m-chlorophenylhydrazone (CCCP) 61% isolates, by chloropromazine (CPZ) 61% isolates, by reserpine (RES) in 61% isolates and by 2,4-dinitro phenol (DNP) in 55% isolates. INTERPRETATION AND CONCLUSIONS:The results obtained in this study confirm that MIC of INH decreased in the presence of efflux pump inhibitors (VER, CCCP, CPZ, DNP, RES) in clinical isolates of Mtb and that the inhibition of efflux pumps by the efflux pump inhibitors can enhance the clinical effect of a drug. The results showed that these efflux pump inhibitors are active against both drug susceptible and drug resistant isolates, indicating that the effect of efflux pump inhibitors is not dependent on the mutational profile of the isolate. We observed in this study that VER was the most effective efflux pump inhibitor.

SUBMITTER: Jaiswal I

PROVIDER: S-EPMC5684805 | biostudies-literature | 2017 Nov-Dec

REPOSITORIES: biostudies-literature

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Effect of efflux pump inhibitors on the susceptibility of <i>Mycobacterium tuberculosis</i> to isoniazid.

Jaiswal Indu I Jain Amita A Verma Sanjeev Kumar SK Singh Pooja P Kant Surya S Singh Mastan M

Lung India : official organ of Indian Chest Society 20171101 6

<h4>Background</h4>Mycobacterium can develop drug resistance (DR) by mutation of its existing gene. However, the existence of DR without mutation shows the need to look for an alternative mechanism such as the role of efflux pumps. In this study, we examined the effect of efflux pump inhibitors on isoniazid (INH) susceptibility in clinical isolates of Mycobacterium tuberculosis (Mtb).<h4>Materials and methods</h4>Resazurin microtiter assay was used to examine the effect of efflux pump inhibitors ...[more]

PMID: 29098993

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Project description:Mycobacterial efflux pumps play a major role in the emergence of antimycobacterial drug resistance. Of particular interest is the proteinaceous multi-drug efflux pump protein Rv1258c that encodes a tetracycline/aminoglycoside resistance (TAP-2)-like efflux pump which is active in susceptible and drug resistant Mycobacterium tuberculosis. Rv1258c is implicated in drug resistance to numerous antimycobacterials including first line drugs rifampicin and isoniazid as well as fluoroquinolone and aminoglycoside antibiotic classes. To date, compounds like verapamil and piperine have been shown to inhibit Rv1258c but no direct evidence for binding or mode of action exist. Therefore in the present study we generated an accurate 3D model of Rv1258c using MODELLER and validated its structure using molecular dynamic simulation studies with GROMACS software. The 3D-structures of Rv1258c and the homologous template 1pw4 were simulated within a POPE/POPG lipid bilayer and found to behave similar. Another important finding was the identification of one local energy minima state of the apo protein, which speaks to the flexibility of the protein and will be investigated further. Extraction of one of the open channel conformations of Rv1258c and blind docking of various structurally diverse putative inhibitors and substrates, allowed for the identification of a probable binding site. Spectinamide was found to bind to a different location on the outside surface of the protein suggesting its ability to avoid the efflux channel. We further identified 246 putative compounds that showed higher binding affinity values to Rv1258c compared to piperine and verapamil. Interaction analysis of the top 20 purchasable compounds identified crucial hydrogen bond interactions with Ser26, Ser45 and Glu243 as well as a pi-pi stacking interaction with Trp32 that accounted for the strong affinity of these compounds for Rv1258c. Future studies will entail purchasing a number of compounds for in vitro activity testing against Mycobacterium tuberculosis.

Dataset Information

Effect of efflux pump inhibitors on the susceptibility of Mycobacterium tuberculosis to isoniazid.

Publications

Effect of efflux pump inhibitors on the susceptibility of <i>Mycobacterium tuberculosis</i> to isoniazid.

Similar Datasets

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