Characterization of Mycobacteria from a Major Brazilian Outbreak Suggests that Revision of the Taxonomic Status of Members of the Mycobacterium chelonae-M-abscessus Group Is Needed

An outbreak of postsurgical infections caused by rapidly growing mycobacteria has been ongoing in Brazil since 2004. the degrees of similarity of the rpoB and hsp65 sequences from the clinical isolates and the corresponding sequences from both the Mycobacterium massiliense and the M. bolletii type strains were above the accepted limit for interspecies variability, leading to conflicting identification results. Therefore, an extensive characterization of members of the M. chelonae-M. abscessus group was carried out. the M. abscessus, M. chelonae, M. immunogenum, M. massiliense, and M. bolletii type strains and a subset of clinical isolates were analyzed by biochemical tests, high-performance liquid chromatography, drug susceptibility testing, PCR-restriction enzyme analysis of hsp65 (PRA-hsp65), rpoB, and hsp65 gene sequencing and analysis of phylogenetic trees, DNA-DNA hybridization (DDH), and restriction fragment length polymorphism ( RFLP) analysis of the 16S rRNA gene (RFLP-16S rRNA). the clinical isolates and the M. abscessus, M. massiliense, and M. bolletii type strains could not be separated by phenotypic tests and were grouped in the phylogenetic trees obtained. the results of DDH also confirmed the >70% relatedness of the clinical isolates and the M. abscessus, M. massiliense, and M. bolletii type strains; and indistinguishable RFLP-16S rRNA patterns were obtained. On the contrary, the separation of clinical isolates and the M. abscessus, M. massiliense, and M. bolletii type strains from M. chelonae and M. immunogenum was supported by the results of PRA-hsp65, DDH, and RFLP-16S rRNA and by the rpoB and hsp65 phylogenetic trees. Taken together, these results led to the proposition that M. abscessus, M. massiliense, and M. bolletii represent a single species, that of M. abscessus. Two subspecies are also proposed, M. abscessus subsp. abscessus and M. abscessus subsp. massiliense, and these two subspecies can be distinguished by two different PRA-hsp65 patterns, which differ by a single HaeIII band, and by differences in their rpoB (3.4%) and hsp65 (1.3%) sequences.Foundation for Research Support of the state of São PauloEuropean CommissionUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilOsped Careggi, Ctr Reg Riferimento Diagnost Micobatteri, Lab Microbiol & Virol, Florence, ItalyInst Adolfo Lutz Registro, Setor Micobacterias, São Paulo, BrazilInst Evandro Chagas, Belem, Para, BrazilUniv Autonoma Madrid, Fac Med, Dept Prevent Med, Madrid, SpainUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023062 São Paulo, BrazilFoundation for Research Support of the state of São Paulo: 06/1533-9European Commission: HEALTH-F3-2008200999Web of Scienc