Gross and histopathological features of tuberculosis in cattle, buffalo and spotted deer (Axis axis) caused by Mycobacterium orygis.

Mycobacterium orygis has been isolated from several cases of tuberculosis in various species of animal in India but documentation of the histopathological lesions caused by this organism is scant. Lung and liver tissues with caseous nodules from cattle (n = 8), lung samples from spotted deer (Axis axis) (n = 5) and lung and mediastinal lymph node samples from buffalo (n = 9) were subjected to histopathology and isolation of Mycobacterium spp. Isolation was carried out using the BACTEC MGIT 960 Automated Mycobacterial Detection System and acid-fast positive cultures were identified to species level using polymerase chain reaction (PCR) employing published primer pairs. Three M. orygis isolates (two from cattle, one from deer) were obtained, whole genome sequenced and the sequences submitted to the National Center for Biotechnology Information Sequence Read Archive. Eight samples (four cattle, one deer and three buffalo) were confirmed as M. orygis positive by PCR. Histopathological examination of the M. orygis-PCR-positive cattle samples revealed acid-fast organisms in lung sections along with macrophages, epithelioid cells, lymphocytes and Langhans giant cells. Granuloma stages I to IV were seen in the cattle and buffalo samples and stage III in the spotted deer sample. This report is the first description of the gross and histopathological lesions of tuberculosis caused by M. orygis in buffalo and documents the gross and histopathological findings of M. orygis tuberculosis in cattle and deer.