Molecular Epidemiology of Mycobacterium Tuberculosis Complex at Nekemte Municipality Abattoir, Western Ethiopia

Abstract

A cross-sectional study was conducted at Nekemte Manicipality Abattoir from September 2009 to May 2010 to estimate the prevalence of bovine tuberculosis (BTB), and characterize its causative agents. Post mortem examination, bacteriological culturing, Zeihl Neelsen staining, multiplex polymerase chain reaction (PCR), and region of difference-4 (RD4) deletion typing were used for investigation. Cattles (1168) were recruited for the study and the prevalence was found to be 5.9% (70/1186) on the basis of gross lesion. 70% of the gross lesion was detected in the thoracic cavity while 25% of the lesion was found in the abdominal cavity. Only 31.4% (22/70) of the suspicious lesions yielded colonies of which 19 were acid-fast positive. Further identification of these 19 isolates using multiplex PCR revealed that 17 isolates belong to the Genus Mycobacterium while the remaining two isolates did not show signal to the Genus. Of the 17 isolates that showed signal to the Genus Mycobacterium, 7 were members of Mycobacterium tuberculosis (M. tuberculosis) complex while the remaining 10 isolates were members of the non-M. tuberculosis complex. Further identification and characterization of the M. tuberculosis complex members using RD4 deletion typing identified four isolates with intact RD4 which could be either M. tuberculosis or M. africanum and three isolates with deleted RD4 thus confirmed to be M. bovis. In conclusion, TB lesions were caused by both the members of M. tuberculosis complex and the non-M. tuberculosis complex Mycobacteria. Hence, as the majority of the isolates was the non-M. tuberculosis complex members, the pathogenecity of these members in cattle needs further study.

Keywords: Mycobacterium tuberculosis; Molecular epidemiology; Cattle; Western Ethiopia; Nekemte; PCR