Direct drug susceptibility testing of Mycobacterium tuberculosis against primary anti-TB drugs in northern India

Anamika Gupta; Shampa Anupurba

doi:10.3855/jidc.1079

Direct drug susceptibility testing of Mycobacterium tuberculosis against primary anti-TB drugs in northern India

Authors

Anamika Gupta Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
Shampa Anupurba Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

DOI:

https://doi.org/10.3855/jidc.1079

Keywords:

Direct NRA, Griess reagent, tuberculosis, turnaround time, MDR-TB

Abstract

Introduction: The present study aimed to evaluate a rapid and inexpensive colorimetric nitrate reductase assay (NRA) performed directly on sputum specimens for detection of drug resistance in Mycobacterium tuberculosis (MTB).

Methodology: A total of 55 sputum samples were decontaminated and processed by modified Petroff's method. A part of the resulting suspension was used to perform direct NRA (DNRA) and direct proportion method (DPM) analysis. Of the 55 samples, 45 could be used to compare the two methods. Indirect drug sensitivity testing (DST) was also done for 14 MTB strains.

Results: Excellent agreement was found between DNRA and DPM testing with κ values of 1, 0.91, 0.91, and 1 for RIF, INH, STR and EMB respectively. The sensitivities and specificities of DNRA compared to that of DPM were observed to be 100 and 100%, 100 and 93%, 95 and 96%, 100 and 100 % for RIF, INH, STR, and EMB respectively. Comparing the results of DNRA, DPM and indirect NRA with those of the gold standard indirect PM for 14 MTB strains showed that sensitivities, specificities and percent agreements were 100, 100 and 100% for all four tested drugs. Results for most of the specimens (55.6%) were available in 21 days with DNRA.

Conclusions: We have saved valuable time by omitting the pre-isolation step and conclude that DNRA is a rapid, accurate and inexpensive method for direct DST of MTB and may become an appropriate alternative method for the resource limited settings.

Author Biographies

Anamika Gupta, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Department of Microbiology,

Institute of Medical Sciences

Shampa Anupurba, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Prof. and Head, Department of Microbiology,

Institute of Medical Sciences

Downloads

Published

2010-06-03

How to Cite

Gupta A, Anupurba S (2010) Direct drug susceptibility testing of Mycobacterium tuberculosis against primary anti-TB drugs in northern India. J Infect Dev Ctries 4:695–703. doi: 10.3855/jidc.1079

Download Citation

Endnote/Zotero/Mendeley (RIS)

Issue

Vol. 4 No. 11: November 2010

Section

Original Articles

License

Authors who publish with this journal agree to the following terms:

Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).