Evaluation of genotype MTBDRplus V2 and genotype MTBDRsl V2 for the diagnosis of extrapulmonary tuberculosis in India

Microbiological diagnosis of extra-pulmonary tuberculosis (EPTB) has been one of the most difficult aspects of tuberculosis (TB) management. Availability of better imaging and diagnostic modalities has led to an increase in the number of diagnosed cases. The current upsurge in multidrug-resistant tuberculosis warrants routine testing of EPTB samples for resistance at baseline with shorter turn-around time. A total of 369 EPTB specimens were subjected to Ziehl-Neelsen (ZN) stain, liquid culture (LC) with phenotypic drug susceptibility testing, MTBDRplus V.2 and MTBDRsl V.2. The molecular categorisation of resistant specimens was further reconfirmed with sequencing. The sensitivity and specificity of MTBDRplus V.2 to detect Mycobacterium tuberculosis (MTB) when compared to ZN stain was 97.9% and 89.2%, respectively while it was 73.4% and 83.8%, respectively when compared to LC. Similarly, for MTBDRsl V.2, the sensitivity and specificity for detection of MTB when compared with ZN was 95.6% and 91.9%, respectively and 75% and 89.2%, respectively when compared to LC. In smear-positive specimens, 94% (141/150) and 86% (129/150) valid results were observed in MTBDRplus V.2 and MTBDRsl V.2, respectively. The utilisation of both MTBDRplus V.2 and MTBDRsl V.2 for the diagnosis of smear-positive EPTB specimens would be useful in programmatic management of TB in high-burden settings.