Mycobacterium nebraskense sp. nov., a novel slowly growing scotochromogenic species.

The characterization of a novel slowly growing, scotochromogenic Mycobacterium species is reported. This previously undescribed mycobacterial species was isolated from five different patients with symptomatic pulmonary infections. All isolates were acid-fast-positive and the mycolic acid profiles were unique and supported placement into the genus Mycobacterium. Phenotypic characteristics of each strain included optimal growth after 3 weeks at a temperature range of 30-35 degrees C, yellow pigmentation after incubation in the dark and production of a heat-stable catalase. The 16S rRNA gene and internal transcribed spacer 1 sequences were identical for all five strains, but distinct from all known mycobacterial species. Phylogenetic analysis based on the 16S rRNA gene sequence placed the novel species within the slowly growing mycobacteria group in close proximity to Mycobacterium malmoense, Mycobacterium avium, Mycobacterium kansasii and Mycobacterium scrofulaceum. These data support the conclusion that the related five described organisms represent a novel Mycobacterium species, for which the name Mycobacterium nebraskense sp. nov. is proposed, with the type strain UNMC-MY1349(T) (=ATCC BAA-837(T)=DSM 44803(T)).