PHYLOGENY OF THE MYCOBACTERIUM-CHELONAE-LIKE ORGANISM BASED ON PARTIAL SEQUENCING OF THE 16S RIBOSOMAL-RNA GENE AND PROPOSAL OF MYCOBACTERIUM-MUCOGENICUM SP-NOV

The Mycobacterium chelonae-like organism (MCLO) is a recently describe d member of the Mycobacterium fortuitum complex which causes posttraum atic skin infections and catheter sepsis. This taxon is a distinct gro up biochemically and has a unique mycolic acid profile as determined b y high-performance liquid chromatography. Its phylogenetic relationshi ps to other mycobacteria, however, have not been studied previously. W e sequenced 1,062 bp of the 16S rRNA genes from three MCLO strains obt ained from the American Type Culture Collection and compared our resul ts with the sequences of previously described tars of rapidly growing and slowly growing mycobacteria. Two biochemically typical strains (AT CC 49650(T) [T = type strain] and ATCC 49651) had identical sequences, while the sequence of a biochemically atypical strain (ATCC 49649) di ffered by 4 bp from the sequence of the two typical strains. The Hammi ng distances between these MCLO strains and related rapidly growing my cobacteria are comparable to the Hamming distances among taxa of rapid ly growing mycobacteria established as species by DNA-DNA hybridizatio n. We propose the name Mycobacterium mucogenicum sp. nov. for this new taxon because of the highly mucoid nature of most isolates on solid m edia.