Rapid confirmation of drug susceptibility in Mycobacterium tuberculosis using MPT 64 Ag based test

To evaluate the possible use of MPT64 based rapid test to detect multi-drug resistant Mycobacterium tuberculosis (M. tuberculosis) in antibiotic broth dilution cultures. Twenty five isolates of M. tuberculosis whose susceptibility pattern had previously been identified by HAIN Genotype MTBDRplus (HainLifecience, Herhen, Germany) were processed and cultured according to the microscopic-observation drug susceptibility technique. These included 20 susceptible, two multi-drug resistant M. tuberculosis and three isoniazid mono-resistant isolates. After 10-day incubation, aspirates from each well were tested with the MPT64 rapid test. The rapid test correctly identified all 25 isolates and detected rifampicin and isoniazid resistance in all but one isoniazid mono-resistant isolate. MPT64 rapid test could be useful in detecting M. tuberculosis and drug resistance from Middlebrook 7H9 antimicrobial broth dilution in resource poor settings without an inverted microscope.