New methods for the detection of resistance in Mycobacterium tuberculosis
نویسندگان
چکیده
The detection of drug resistance in tuberculosis takes several weeks with conventional methods, and there is a high cost associated with the use of faster methods like commercial kits or molecular techniques. This work evaluates the nitrate reductase method (NRM), the MTT colorimetric assay and resazurin (RES) as alternative assays for the rapid detection of resistance to first line antituberculosis drugs, using the method of the proportions (MP) as a reference. The inhibitory concentrations obtained for the colorimetric assays were 0.25 μg/mL or higher for isoniazide (INH), 1 μg/mL or higher for streptomycin (STR), 4 μg/mL or higher for ethambutol (ETH), and 0.25 μg/mL or higher for rifampicin (RIF). The sensitivity of the assays was higher than 90.0% for all the drugs; the specificity was higher than 88.5% for INH, STR and RIF but lower (higher than 57.8%) for ETH. The NRM showed good correlation for the 4 drugs (sensitivity and specificity higher than 93.7%), and the concordance was 88.2%, 90.7% and 98.2% for RES, MTT and NRM, respectively. This study shows a high level of agreement between the new methods and the MP for the detection of resistance to INH and RIF, and therefore proves their validity as alternatives that can be easily implemented at low-budgeted laboratories.
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تاریخ انتشار 2005