Characterization of Mycobacterium orygis as M. tuberculosis complex subspecies

Abstract

The oryx bacilli are Mycobacterium tuberculosis complex organisms for which phylogenetic position and host range are unsettled. We characterized 22 isolates by molecular methods and propose elevation to subspecies status as M. orygis. M. orygis is a causative agent of tuberculosis in animals and humans from Africa and South Asia.

Figure 1

Spoligotyping and 24-locus variable number tandem repeat (VNTR) typing results for Mycobacterium orygis. A) Spoligotyping patterns for the oryx bacillus isolates in this study; ST587 is the most common pattern (labeled SB0422 at www.mbovis.org), with minor deviations. B) Minimum spanning tree based on 24-locus VNTR typing results for the oryx bacillus isolates in this study. One type dominates, with few strains representing minor variations. The dominant clone includes isolates from humans and animals. P, pulmonary; LN, lymph node; G, gastric juice. Both panels were created by using BioNumerics version 6.1 software (Applied Maths, Sint-Martens-Latem, Belgium); similarity coefficients were calculated by using Dice (spoligotyping) and Pearson (VNTR) methods; cluster analysis was done by the UPGMA (unweighted pair group method with arithmetic mean). Isolate 10–1562 (cow, Bangladesh) could not be included in (B) because of insufficient DNA.

Figure 2

Updated phylogeny of the Mycobacterium tuberculosis complex based on the findings of Brosch et al. (2). Combined findings place Mycobacterium orygis at a distinct phylogenetic position between the M. africanum/dassie bacillus/M. mungi cluster and M. microti.