Mycobacterium barrassiae sp. nov., a Mycobacterium moriokaense group species associated with chronic pneumonia

Three identical isolates of new rapidly growing mycobacteria (RGM) were recovered from the bronchial aspirate and sputum from a 49-year-old woman presenting with lung lesions. The case met the American Thoracic Society criteria for the diagnosis of nontuberculous mycobacterial infection. The three isolates grew in 3 days at 24 to 42 degrees C. The 16S rRNA gene sequence analysis indicated that the sequences of the isolates were identical and shared 99.7% and 98.1% similarities with those of Mycobacterium moriokaense and Mycobacterium gadium, respectively. Partial 723-bp rpoB sequence analyses indicated that the sequences of the isolates shared 95.8% and 92.3% similarities with those of M. moriokaense and M. gadium, respectively. Polyphasic identification (including biochemical tests; antimicrobial susceptibility profiling; and hsp65, recA, and sodA gene sequence analyses, as well as G+C content determination and cell wall fatty acid composition analysis) supported the evidence that these isolates were representative of a new species. Phylogenetic analyses confirmed the close relationships of the isolates with M. moriokaense and the defined M. moriokaense group. These isolates were susceptible to the antimicrobials currently recommended for the treatment of RGM infections. These isolates differed from M. moriokaense by their susceptibility to vancomycin. We propose the name Mycobacterium barrassiae sp. nov. for this new species. The type strain is N7T (CIP 108545T and CCUG 50398T).