Drug susceptibility testing of Mycobacterium tuberculosis by a nitrate reductase assay applied directly on microscopy-positive sputum samples. (March 2015)

• Record Type: Journal Article
• Authors: Kammoun, S.; Smaoui, S.; Marouane, C.; Slim, L.; Messadi-Akrout, F.
• Is Part Of: International journal of mycobacteriology. Volume 4 (2015: Mar.)Supplement 1
• Page Start: 108
• Publication Date: 2015-03
• Subjects: Drug resistance -- M. tuberculosis -- Drug susceptibility testing -- Sputum; Mycobacteria -- Periodicals; Mycobacterial diseases -- Periodicals; Mycobacteriaceae; Mycobacteria; Electronic journals; Periodicals; 579.374
• DOI: 10.1016/j.ijmyco.2014.10.049
• Languages: English
• ISSNs: 2212-5531

Abstract

Abstract: Aims and objectives: Current methods for drug susceptibility testing (DST) of Mycobacterium tuberculosis (MTB) are either costly or slow. As the prevalence of multidrug-resistant (MDR) strains increases, the need for fast, reliable, and inexpensive methods is obvious. This study evaluated a rapid colorimetric nitrate reductase assay (NRA) for direct DST of MTB directly from clinical sputum samples. Methods: A total of 111 sputa with positive microscopy results for acid-fast bacilli (AFB) with more than 10 AFB per high-power field were used in the study. The samples were decontaminated using the modified Petroff method. The NRA results were compared with the reference indirect proportion method. Results: The sensitivity and the specificity of the direct NRA were 90% and 97.3%, 92.6% and 98.2%, 52.9% and 100%, and 28.6% and 100% for rifampin, isoniazid, streptomycin, and ethambutol, respectively. The results were in most cases available in 28 days (84.3%). Conclusions: The direct NRA could be used as a rapid, inexpensive, and accurate method to determine rifampin and isoniazid susceptibility directly from sputum. The technique might become a valid alternative to traditional methods, especially in low-income countries.