Identification and Characterisation of Nontuberculous Mycobacteria in African Buffaloes (), South Africa.

Diagnosis of bovine tuberculosis (bTB) may be confounded by immunological cross-reactivity to antigens when animals are sensitised by certain nontuberculous mycobacteria (NTMs). Therefore, this study aimed to investigate NTM species diversity in African buffalo () respiratory secretions and tissue samples, using a combination of novel molecular tools. Oronasal swabs were collected opportunistically from 120 immobilised buffaloes in historically bTB-free herds. In addition, bronchoalveolar lavage fluid (BALF; = 10) and tissue samples ( = 19) were obtained during post-mortem examination. Mycobacterial species were identified directly from oronasal swab samples using the Xpert MTB/RIF Ultra qPCR (14/120 positive) and GenoType CM (104/120 positive). In addition, all samples underwent mycobacterial culture, and PCRs targeting 65 and were performed. Overall, 55 NTM species were identified in 36 mycobacterial culture-positive swab samples with presence of -6 or -10 detected in 20 of 36 isolates. The predominant species were complex and Nontuberculous mycobacteria were also isolated from 6 of 10 culture-positive BALF and 4 of 19 culture-positive tissue samples. Our findings demonstrate that there is a high diversity of NTMs present in buffaloes, and further investigation should determine their role in confounding bTB diagnosis in this species.