Description of Mycobacterium conceptionense sp. nov., a Mycobacterium fortuitum group organism isolated from a posttraumatic osteitis inflammation

Abstract

A nonpigmented rapidly growing mycobacterium was isolated from wound liquid outflow, bone tissue biopsy, and excised skin tissue from a 31-year-old woman who suffered an accidental open right tibia fracture and prolonged stay in a river. The three isolates grew in 3 days at 24 to 37 degrees C. 16S rRNA sequence analyses over 1,483 bp showed that they were identical and shared 99.7% (4-bp difference) sequence similarity with that of Mycobacterium porcinum, the most closely related species. Partial rpoB (723 bp) sequence analyses showed that the isolates shared 97.0% sequence similarity with that of M. porcinum. Further polyphasic approaches, including biochemical tests, antimicrobial susceptibility analyses, and hsp65, sodA, and recA gene sequence analysis, as well as % G+C determination and cell wall fatty acid composition analysis supported the evidence that these isolates were representative of a new species. Phylogenetic analyses showed the close relationship with M. porcinum in the Mycobacterium fortuitum group. The isolates were susceptible to most antibiotics and exhibited evidence for penicillinase activity, in contrast to M. porcinum. We propose the name Mycobacterium conceptionense sp. nov. for this new species associated with posttraumatic osteitis. The type strain is D16(T) (equivalent to CIP 108544(T) and CCUG 50187(T)).

FIG. 1.

Phylogenetic tree of the partial rpoB gene sequences of M. conceptionense and 24 RGM prepared by using the neighbor-joining method and Kimura's two-parameter distance correction model. The support of each branch, as determined from 1,000 bootstrap samples, is indicated by the value at each node (as a percentage). M. tuberculosis and M. leprae were used as the out-groups. The scale bar represents a 2% difference in nucleotide sequences.