Novel Mycobacterium avium species isolated from Black Wildebeest (Connochaetes gnou) in 5 South Africa

Abstract

A study was undertaken to isolate and characterize Mycobacterium species from black wildebeest suspected of being infected with tuberculosis in South Africa. This led to the discovery of a new Mycobacterium avium species, provisionally referred to as the Gnou isolate from black wildebeest (Connochaetus gnou). Sixteen samples from nine black wildebeest were processed for Mycobacterium isolation. Following decontamination; samples were incubated in an ordinary incubator at 37°C on Löwenstein-Jensen slants and in liquid medium tubes using the BACTECTM MGITTM 960 system respectively. Identification of the isolate was done by standard biochemical tests and using the line probe assay from the GenoType® CM/AS kit (Hain Life Science GmbH, Nehren, Germany). The DNA extract was also analyzed using gene sequencing. Partial gene sequencing and analysis of 16S rRNA gene, 16S-23S rRNA (ITS), rpoB and hsp65 and phylogenetic analyses by searching GenBank using the BLAST algorithm were conducted. Phylogenetic trees were constructed using four methods, namely Bayesian inference, maximum likelihood, maximum parsimony and neighbor-joining methods. The isolate was identified as Mycobacterium intracellulare using the GenoType® CM/AS kit and as Mycobacterium avium complex (MAC) by gene sequencing. The gene sequence targeting all the genes, ITS, 16S rRNA, rpoB and hsp65 and phylogenetic analyses indicated that this isolate presented a nucleotide sequence different from all currently published sequences, and its position was far enough from other MAC species to suggest that it might be a new species.