Taxonomic variation in the Mycobacterium fortuitum third biovariant complex:: description of Mycobacterium boenickei sp nov., Mycobacterium neworleansense sp nov., Mycobacterium neworleansense sp nov and Mycobacterium brisbanense sp nov and recognition of Mycobacterium porcinum from human clinical isolates

The Mycobacterium fortuitum third biovariant complex (sorbitol-negative and sorbitol-positive) contains unnamed taxa first characterized in 1991. These organisms can cause respiratory infections, a spectrum of soft tissue and skeletal infections, bacteraemia and disseminated disease. To evaluate this group of organisms, clinical reference isolates and the type strains of M. fortuitum third biovariant complex sorbitol-negative (n=21), M. fortuitum third biovariant complex sorbitol-positive (n=3), M. fortuitum (n=3), Mycobacterium peregrinum (pipemidic acid-susceptible) (n=1), Mycobacterium porcinum (n=1), Mycobacterium senegalense (n=2) and Mycobacterium septicum (n=1) were characterized by using conventional phenotypic (morphological, physiological and antimicrobial susceptibilities), chemotaxonomic (HPLC and cellular fatty acids) and genotypic [RFLP of the rRNA gene (ribotyping), PCR-RFLP of a 439 by segment of the 65 kDa hsp gene (PCR restriction analysis) and 16S rRNA gene sequence] analysis, DNA G+C content and DNA-DNA relatedness analyses. The results of these studies indicated that the strains comprised M. porcinum (n=13), M. septicum (n=1) and four novel closely related genetic groups within the M. fortuitum third biovariant complex: Mycobacterium boenickei sp. nov. (n=6), Mycobacterium houstonense sp. nov. (n=2), Mycobacterium neworleansense sp. nov. (n=1) and Mycobacterium brisbanense sp. nov. (n=1), with type strains ATCC 49935(T) (=W5998(T)=DSM 44677(T)), ATCC 49403(T) (=W5198(T)=DSM 44676(T)) ATCC 49404(T) (=W6705(T)=DSM 44679(T)) and ATCC 49938(T) (=W6743(T)=DSM 44680(T)), respectively.