Resazurin microtiter assay for detection of drug resistance and determination of critical concentration of cycloserine resistance of Mycobacterium tuberculosis

We evaluated the feasibility of resazurin microtiter assay (REMA) for detecting cycloserine resistance of Mycobacterium tuberculosis. The cutoff value of the critical concentration of cycloserine resistance in vitro about M. tuberculosis isolates was determined innovatively by drawing the receiver operating characteristic (ROC) curve for the first time. The spending time of REMA ranged from 6 to 9 days. The ROC curve analysis showed that the area under the curve (AUC) was 0.950, and P value was <0.001. The critical concentration of cycloserine in vitro was >16 μg/ml based on the ROC curve. At this point, the sensitivity of REMA was 79.17%, and the specificity was 100% when compared to the proportion method (PM). Resazurin method was found to be simple, reliable and inexpensive to perform for the rapid detection of anti-tuberculous drugs.