Rapid detection on resistance of rifampicin and isoniazid for Mycobacterium tuberculosisclinical isolates by microplate Alamar Blue assay

The feasibility of microplate Alamar Blue assay for detecting the resistance of rifampicin and isoniazid in Mycobacterium tuberculosis clinical isolates was investigated in the present study,in which MIC of rifampicin of 41 Mycobacterium tuberculosis isolates and MIC of isoniazid of 70 isolates was detected by microplate Alamar Blue assay,and the time for detection was recorded.The receiver operating characteristic curve(ROC) was used to detect the resistant threshold value of rifampicin and isoniazid,and compared them with the results from conventional proportional method.Results showed that the resistant threshold value of rifampicin and isoniazid were all 0.5 μg/mL for microplate Alamar Blue assay.And compared to the gold standard proportional method,the sensitivity and specificity were 100.0% and 100.0% for rifampicin,96.6% and 100.0% for isoniazid,respectively.The time of detection for microplate Alamar Blue assay was 8 days.In conclusion,as it is simple,sensitive and rapid,the microplate Alamar Blue assay could be an alternative method for rapid detection for the resistance of rifampicin and isoniazid for Mycobacterium tuberculosis clinical isolates.