Nontuberculosis mycobacteria are the major causes of tuberculosis like lesions in cattle slaughtered at Bahir Dar Abattoir, northwestern Ethiopia

Abstract

BackgroundThe main cause of bovine tuberculosis (bTB) is believed to be Mycobacterium bovis (M. bovis). Nontuberculosis mycobacteria (NTM) are neglected but opportunistic pathogens and obstacles for bTB diagnosis. This study aimed to isolate and characterize the mycobacteria organisms involved in causing TB-like lesions in cattle in northwestern Ethiopia.ResultsA total of 2846 carcasses of cattle were inspected for TB lesions. Ninety six tissues (including lymph nodes such as submandibular, retropharyngeal, tonsilar, mediatinal, bronchial and mesenteric, and organs such as lung, liver and kidney) with suspicious TB lesion(s) were collected and cultured on Lowenstein-Jensen medium. Twenty one showed culture growth, of which only 17 were identified containing acid fast bacilli (AFB) by Ziehl–Neelsen staining. Among the 17 AFB isolates 15 generated a polymerase chain reaction product of 1030 bp by gel electrophoresis based on the 16S ribosomal RNA gene amplification. No M. tuberculosis complex species were isolated. Further characterization by Genotype Mycobacterium CM assay showed 6 isolates identified as M. peregrinum. Eight isolates represented by mixed species, which includes M. fortuitum-peregrinum (3 isolates), M. gordonae-peregrinum (3 isolates) and M. fortuitum-gordonae-peregrinum (2 isolates). One NTM could not be interpreted.ConclusionA significant number of NTM species were isolated from TB-like lesions of grazing cattle slaughtered at Bahir Dar Abattoir. Such finding could suggest the role of NTM in causing lesions in cattle. Further investigations are recommended on the pathogenesis of the reported NTM species in cattle, and if they have public health significance.

A Meta-Analysis of the Effect of Bacillus Calmette-Guérin Vaccination Against Bovine Tuberculosis: Is Perfect the Enemy of Good?

“…It is noteworthy that most experimental trials have used M. bovis as the challenge strain. However, M. bovis is not the only causative agent of bTB since M. tuberculosis and other members of the M. tuberculosis complex are frequently isolated from cattle samples, and certain species of non-tuberculous mycobacteria (NTM) that contain virulence factors encoded in the Region of Difference-1 are also known to cause TB-like lesions ( 63 , 64 ). Hence, future studies are needed to better estimate efficacy of BCG vaccine-induced protection with locally relevant bTB causing mycobacteria other than M. bovis .…”

Second line molecular diagnosis for bovine tuberculosis to improve diagnostic schemes

“…NTM or Actinomycetales, have been identified in the lesions. Indeed, bTB-like lesions could also be caused by other granuloma forming organisms such as NTM or Nocardia species [ 15 ]. Moreover, mycobacteria and some Actinomycetales (of the genus Nocardia , Rhodococcus or Corynebacterium ) shared the same tinctorial properties and thus are identified as acid resistant bacilli by Ziehl Neelsen staining [ 16 ].…”

Occurrence of Virulence Genes and Antimicrobial Resistance of E. coli O157:H7 Isolated from the Beef Carcass of Bahir Dar City, Ethiopia

“…Bahir Dar city is in the northwestern part of Ethiopia, 565 km away from Addis Ababa at latitude 11°35′37.10″ N and longitude 37°23′26.77″E on the south of Lake Tana, the upper water shed of the Blue Nile River ( Figure 1 ) [ 24 ]. Cattle slaughtered at the Bahir Dar city abattoir are mainly of the zebu type and originated from different districts of northwest Ethiopia [ 25 ].…”