Isolation and genetic analysis of mycobacteria from suspect tuberculous lesions in slaughtered cattle from Wolaita, Ethiopia.

Abstract

Bovine tuberculosis (bTB), caused by Mycobacterium bovis and other members of the Mycobacterium tuberculosis complex (MTBC), is a significant concern for livestock and public health in Ethiopia. This study aimed to isolate and genetically characterize the causative agents of bTB in cattle from four abattoirs in the Wolaita zone of Ethiopia. A total of 2,251 cattle were examined post-mortem, and suspect tuberculous lesions were identified in 122 animals. From these animals, 180 tissue samples were collected and processed for bacteriological culture and genetic analysis, including the Loopamp^™ commercial loop-mediated isothermal amplification kit, PCR targeting RD4 and RD9 loci and whole-genome sequencing (WGS). Bacteriological culture using mycobacteria growth indicator tube and Lowenstein-Jensen media ultimately identified 18 culture-positive samples, with WGS confirming M. bovis in lesions from four animals and M. tuberculosis in lesions from one animal. The M. bovis and M. tuberculosis isolates showed genetic similarity to previously identified MTBC lineages in Ethiopia. The presence of M. tuberculosis in cattle raises concerns about human-to-animal transmission. Additionally, non-tuberculous mycobacteria were isolated from lesions from multiple animals. Our study genetically characterized bacteria from suspect tuberculous lesions and provides the research community with new genome data for Ethiopian isolates of M. bovis and M. tuberculosis.