Disseminated infection with Mycobacterium tilburgii in a male immunocompromised patient

Nontuberculous mycobacteria: Insights on taxonomy and evolution

Seventy years have passed since Ernest H. Runyon presented a phenotypic classification approach for nontuberculous mycobacteria (NTM), primarily as a starting point in trying to understand their clinical relevance. From numerical taxonomy (biochemical testing) to 16S rRNA gene sequencing to whole genome sequencing (WGS), our understanding of NTM has also evolved. Novel species are described at a rapid pace, while taxonomical relationships are re-defined in large part due to the accessibility of WGS. The evolutionary course of clonal complexes within species is better known for some NTM and less for others. In contrast with M. tuberculosis, much is left to learn about NTM as a whole.

Novel Mycobacterium avium Complex Species Isolated From Black Wildebeest (Connochaetes gnou) in South Africa

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 complex species, provisionally referred to as the Gnou isolate from black wildebeest (Connochaetes 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 BACTEC^™ MGIT^™ 960 system, respectively. Identification of the isolate was carried out by standard biochemical tests and using the line probe assay from the GenoType^® CM/AS kit (Hain Lifescience GmbH, Nehren, Germany). The DNA extract was also analysed using gene sequencing. Partial gene sequencing and analysis of 16S rRNA gene, and 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 neighbour-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.