Detection of multidrug-resistant tuberculosis using MGIT™(TM) and MAS-PCR in Tripura, India

Multidrug-resistant tuberculosis (MDR-TB) poses a global threat that is further compounded by the human immunodeficiency virus (HIV) epidemic.

To detect MDR-TB among pulmonary TB (PTB) patients with or without HIV coinfection by isolating and identifying Mycobacterium tuberculosis from clinical samples and performing drug susceptibility testing (DST).

Sputum was collected from presumed PTB cases. Microscopic examination was performed following Ziehl-Neelsen (ZN) staining and cultured in Löwenstein-Jensen (LJ) medium. First-line anti-tuberculosis DST of the isolates was performed using MGIT™ (Mycobacterial Growth Indicator Tube) and multiplex allele-specific polymerase chain reaction (MAS-PCR).

Of 172 study subjects, 59.3% (102/172) were smear-positive and 40.7% (70/172) were smear-negative. In the smear-positive and -negative groups, respectively 62.7% (64/102) and 8.6% (6/70) were culture-positive. DST on MGIT showed a cumulative resistance of 7.1% (5/70) to isoniazid (INH) and rifampicin. More ethambutol (EMB) and combined INH+EMB resistance was detected using MAS-PCR.

MDR-TB is a problem in Tripura, and culture and phenotypic DST are required for diagnosis. MAS-PCR may provide an alternative rapid screening tool.