A new rapid colourimetric method for testing Mycobacterium tuberculosis susceptibility to isoniazid and rifampicin: a crystal violet decolourisation assay

Mem. Inst. Oswaldo Cruz

Uzun

et al. 2015

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The purpose of this study is to evaluate four rapid colourimetric methods, including the resazurin microtitre assay (REMA), malachite green decolourisation assay (MGDA), microplate nitrate reductase assay (MNRA) and crystal violet decolourisation assay (CVDA), for the rapid detection of multidrug-resistant (MDR) tuberculosis. Fifty Mycobacterium tuberculosis isolates were used in this study. Eighteen isolates were MDR, two isolates were only resistant to isoniazid (INH) and the remaining isolates were susceptible to both INH and rifampicin (RIF). INH and RIF were tested in 0.25 µg/mL and 0.5 µg/mL, respectively. The agar proportion method was used as a reference method. MNRA and REMA were performed with some modifications. MGDA and CVDA were performed as defined in the literature. The agreements of the MNRA for INH and RIF were 96% and 94%, respectively, while the agreement of the other assays for INH and RIF were 98%. In this study, while the specificities of the REMA, MGDA and CVDA were 100%, the specificity of the MNRA was lower than the others (93.3% for INH and 90.9% for RIF). In addition, while the sensitivity of the MNRA was 100%, the sensitivities of the others were lower than that of the MNRA (from 94.1-95%). The results were reported on the seventh-10th day of the incubation. All methods are reliable, easy to perform, inexpensive and easy to evaluate and do not require special equipment.

Section: Discussionmentioning

confidence: 90%

Evaluation of four colourimetric susceptibility tests for the rapid detection of multidrug-resistant Mycobacterium tuberculosis isolates

Mem. Inst. Oswaldo Cruz

Uzun

et al. 2015

Self Cite

“…CVDA was developed by Coban19 in 2014. In his study, sensitivity and specificity were 92.5% and 96.4%for INH and were 88.8% and 100% for RIF.…”

Section: Discussionmentioning

confidence: 99%

“…After the preparation oh this reagent, it should be used freshly in the test. Although the preparation and standardization of LJ medium is very difficult, the test is performed commonly on this medium619. Resazurin powder increases cost burden of the resazurin microplate method.…”

Section: Discussionmentioning

confidence: 99%

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Multicenter evaluation of crystal violet decolorization assay (CVDA) for rapid detection of isoniazid and rifampicin resistance in Mycobacterium tuberculosis

Biçmen

et al. 2016

Sci Rep

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The aim of this multicenter study was to evaluate the performance of the crystal violet decolorization assay (CVDA) for detection of multidrug resistant tuberculosis (MDR-TB). This study was performed in 11 centers in two phases. A total of 156 isolates were tested for INH and RIF resistance. In the phase I, 106 clinical isolates were tested in the Center 1–7. In the phase 2, 156 clinical isolates were tested in the center 1–6, center 8–11. Eighty six of 156 tested isolates were the same in phase I. Agreements were 96.2–96.8% for INH and 98.1–98.7% for RIF in the phase I-II, respectively. Mean time to obtain the results in the phase I was 14.3 ± 5.4 days. In the phase II, mean time to obtain the results was 11.6 ± 3.5 days. Test results were obtained within 14days for 62.3% (66/106) of isolates in the phase I and 81.4% (127/156) of isolates in the phase II. In conclusion, CVDA is rapid, reliable, inexpensive, and easy to perform for rapid detection of MDR-TB isolates. In addition, it could be adapted for drug susceptibility testing with all drugs both in developed and developing countries.

“…Recently, new rapid, inexpensive, reliable and reproducible colorimetric methods including nitrate reductase assay (NRA), resazurin microtiter assay (REMA), malachite green decolorization assay and crystal violet decolorization assay (CVDA) have been developed ( Farnia et al 2008 , Coban & Uzun 2013 , Coban 2014 , Coban et al 2014a , b ).…”

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confidence: 99%

Evaluation of crystal violet decolorization assay for minimal inhibitory concentration detection of primary antituberculosis drugs against Mycobacterium tuberculosis isolates

Mem. Inst. Oswaldo Cruz

Uzun

et al. 2016

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In this study we evaluated the crystal violet decolorization assay (CVDA) for detection of minimum inhibitory concentration (MIC) of antituberculosis drugs. 53 isolates were tested in this study and 13 of them were multidrug resistant (MDR) isolates. The antibiotics concentrations were 2-0.06 mg/L for isoniazid (INH) and rifampicin (RIF) and were 16-0.25 mg/L for streptomycin (STM) and ethambutol (EMB). Crystal violet (CV-25 mg/L) was added into the microwells on the seventh day of incubation and incubation was continued until decolorization. Decolorization of CV was the predictor of bacterial growth. Overall agreements for four drugs were detected as 98.1%, and the average time was detected as 9.5 ± 0.89 day after inoculation. One isolate for INH and two isolates for STM were determined resistant in the reference method, but susceptible by the CVDA. One isolate was susceptible to EMB by the reference method, but resistant by the CVDA. All results were concordant for RIF. This study shows that CVDA is a rapid, reliable and suitable for determination of MIC values of Mycobacterium tuberculosis. And it can be used easily especially in countries with limited-sources.