PCR-based detection of Mycobacterium tuberculosis complex (MTBC) in different bovine samples from Guwahati, Northeast India

Bovine tuberculosis (bTB) is a chronic and often overlooked zoonotic disease caused by Mycobacterium bovis , a globally distributed pathogen within the group Mycobacterium tuberculosis complex (MTBC). The present study was conducted to detect Mycobacterium tuberculosis complex (MTBC) at the molecular level in clinical and slaughterhouse samples from bovines. A total of 620 animal samples ( milk-360, nasal swabs-150, and tissue-110) were screened using polymerase chain reaction (PCR) with primers specific for the Mycobacterium genus-specific hsp65 gene, MTBC-specific IS6110 and IS1081 . Tissue samples were initially processed for microbiological analysis using Ziehl-Neelsen (Z-N) staining to detect acid-fast bacilli, followed by isolation of mycobacteria from the Z-N positive samples. Out of 620 samples, the hsp65 gene was detected in 43 (6.9%) samples and further molecular analysis confirmed that 24 of these were MTBC-positive. Of the 110 tissue samples examined by Ziehl-Neelsen (Z-N) staining, 12 (10.9%) were positive for acid-fast bacilli. However, only two samples were successfully isolated in Lowenstein-Jensen (L-J) media and detected as MTBC by PCR and confirmed through sequencing. This study highlights the widespread presence of bovine tuberculosis in these understudied dairy farms in Guwahati, the largest city in Northeast India. The findings emphasize the need for a comprehensive epidemiological study and the implementation of a One Health approach for the strategic control and prevention of bTB in the region.