Resazurin Microtiter Assay Plate: Simple and Inexpensive Method for Detection of Drug Resistance in <i>Mycobacterium tuberculosis</i>

A method for detecting multidrug-resistant Mycobacterium tuberculosis by using a reduction of resazurin is described. Eighty clinical isolates were evaluated against isoniazid and rifampin; results at 7 days were compared with those of the proportion method. Specificity and sensitivity were excellent. The method is simple, inexpensive, and rapid and might be used with other antituberculosis drugs.