A description of Mycobacterium chelonae subsp. gwanakae subsp. nov., a rapidly growing mycobacterium with a smooth colony phenotype due to glycopeptidolipids

Abstract

Three rapidly growing mycobacterial strains, MOTTH4W, MOTT36W(T) and MOTT68W, were isolated from the sputa of three independent Korean patients co-infected with Mycobacterium yongonense Type II strains. The 16S rRNA gene sequences of all three strains were unique, which were closest to that of Mycobacterium chelonae subsp. bovis KCTC 39630(T) (99.9 % similarity). Multilocus sequence typing analysis targeting 10 housekeeping genes including hsp65 and rpoB revealed the distinct phylogenetic location of these strains, which were clustered with M. chelonae subsp. chelonae ATCC 35752(T) and M. chelonae subsp. bovis KCTC 39630(T). Phylogenetic analysis based on whole genome sequences revealed a 95.89 % average nucleotide identity (ANI) value with M. chelonae subsp. chelonae, slightly higher than the 95.0 % ANI criterion for determining a novel species. In addition, phenotypic characteristics such as a smooth colony morphology and growth inhibition at 37 degrees C, distinct MALDI-TOF MS profiles of extracted total lipids due to surface glycopeptidolipids, and distinct drug susceptibility profiles further supported the taxonomic characterization of these strains as representing a novel subspecies of Mycobacterium chelonae. Mycobacterium chelonae subsp. gwanakae subsp. nov. is proposed and the type strain is MOTT36W(T) (=KCTC 29127(T) =JCM 32454(T)).