Non-tuberculous mycobacteria, not Mycobacterium bovis, are a significant cause of TB-like lesions observed in slaughtered cattle in Ghana

OBJECTIVES: The aim was to isolate and identify the species of mycobacteria causing tuberculous-like (TB-like) lesions in cattle in Ghana. METHODS: Between 2019 and 2020, 68 bovine tissue samples with TB-like lesions, identified during post slaughter examination, were obtained from four major abattoirs close to border towns in Ghana. The samples were cultured on Lowenstein–Jensen medium. Isolated bacteria were characterized by Ziehl–Neelsen staining and observation for acid-fast bacilli (AFB) under a microscope. DNA was extracted from AFB-positive isolates, and mycobacterial speciation was performed by line probe assay using GenoType Mycobacterium CM and also with mycobacterial 16S rRNA gene amplification and sequencing. RESULTS: No Mycobacterium bovis was identified; however 53 bacterial isolates were obtained, of which 41 were non-tuberculous mycobacteria (NTM) strains and 12 were gram-positive bacteria. The predominant NTM species was M. fortuitum (43.9%, 18/41), with the rest being M. novocastrense, M. terrae, M. flavescens, M. holsaticum, M. cosmeticum, M. virginiense, M. intracellulare, M. mageritense, M. minnesotensis, M. duvalii, M. lehmannii, and M. koreense. CONCLUSIONS: In cattle, NTM contribute significantly to lesions observed during slaughter examination and may be an important cause of zoonotic tuberculosis. A One Health surveillance of NTM in Ghana would provide insights into their clinical significance.