Mycobacterium kyorinense sp. nov., a novel, slow-growing species, related to Mycobacterium celatum, isolated from human clinical specimens.

A novel, non-pigmented, slow-growing mycobacterium was identified on the basis of biochemical and nucleic acid analyses, as well as growth characteristics. Three isolates were cultured from clinical samples (two from sputum and one from pus in lymph nodes) obtained from three immunocompetent patients with infections. Bacterial growth occurred at 28-42 degrees C on Middlebrook 7H11-OADC agar. The isolates showed negative results for Tween hydrolysis, nitrate reductase, semiquantitative catalase, urease activity, 3 day arylsulfatase activity, pyrazinamidase, tellurite reduction and niacin accumulation tests, but positive results for 14 day arylsulfatase activity and heat-stable catalase tests. The isolates contained alpha-, keto-, and dicarboxymycolates in their cell walls. Sequence analysis revealed that all isolates had identical, unique 16S rRNA sequences. Phylogenetic analysis of the 16S rRNA, rpoB, hsp65 and sodA gene sequences confirmed that these isolates are unique but closely related to Mycobacterium celatum. DNA-DNA hybridization of the isolates demonstrated less than 50 % reassociation with M. celatum and Mycobacterium branderi. On the basis of these findings, a novel species designated Mycobacterium kyorinense sp. nov. is proposed. The type strain is KUM 060204(T) (=JCM 15038(T)=DSM 45166(T)).