Isolation and analysis of the molecular epidemiology and zoonotic significance of Mycobacterium tuberculosis in domestic and wildlife ruminants from three states in India.

Abstract

The majority of tuberculosis cases in ruminants are caused by Mycobacterium bovis (MB). However, in this study, the authors reported the isolation of Mycobacterium tuberculosis (MT) from bovine milk, nasal swabs and post-mortem tissue samples (n = 841) collected from cattle and buffaloes in the states of Telangana, Maharashtra and Gujarat in India in the period from 2010 to 2015. The isolates (n = 7) were confirmed as Mycobacterium due to their growth characteristics and colony morphology in a commercial liquid medium Mycobacterial Growth Indicator Tube (MGIT)™ employing the BD BACTEC™ MGIT™ 960 system and the Löwenstein-Jensen (LJ) medium supplemented with glycerol but not with sodium pyruvate, and BD-DIFCO™ Middlebrook 7H10 agar containing oleic albumin dextrose catalase (OADC). These isolates were initially identified as members of the M. tuberculosis complex (MTC) using a commercial nested polymerase chain reaction (PCR) kit based on the IS6110 MTC specific nucleotide sequence. The isolates were confirmed as MT using three commercial line probe assay kits, were further genotyped, and the spoligotypes identified were of East African Indian (EAI) 3_IND, EAI5, Central-Asian (CAS) 1_DELHI, U and T1 lineages. Two MT isolates from one antelope (Antilope cervipara) andone gazelle (Gazella bennettii) from Gujarat, which were identified previously, were spoligotyped during this study and identified as belonging to EAI3_IND and EAI5 lineages, respectively. The epidemiological significance and zoonotic implications of regional presence and documentation of the same or two differents poligotypes in different species within the family Bovidae as well as humans is discussed.