Proposal to elevate the genetic variant MAC-A, included in the Mycobacterium avium complex, to species rank as Mycobacterium chimaera sp. nov

• Published in: International journal of systematic and evolutionary microbiology Vol. 54; no. 4; pp. 1277 - 1285
• Main Authors: Tortoli, Enrico, Rindi, Laura, Garcia, Maria J, Chiaradonna, Patrizia, Dei, Rosanna, Garzelli, Carlo, Kroppenstedt, Reiner M, Lari, Nicoletta, Mattei, Romano, Mariottini, Alessandro, Mazzarelli, Gianna, Murcia, Martha I, Nanetti, Anna, Piccoli, Paola, Scarparo, Claudio
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.07.2004; Society for General Microbiology
• Subjects: Aged; Bacteriology; Biological and medical sciences; DNA Fingerprinting; DNA Transposable Elements; DNA, Bacterial - chemistry; DNA, Ribosomal - chemistry; DNA, Ribosomal Spacer - chemistry; Female; Fundamental and applied biological sciences. Psychology; Genes, rRNA; Humans; Male; Microbial Sensitivity Tests; Microbiology; Middle Aged; Molecular Sequence Data; Mycobacterium avium; Mycobacterium avium Complex - chemistry; Mycobacterium avium Complex - classification; Mycobacterium avium Complex - genetics; Mycobacterium avium Complex - isolation & purification; Mycobacterium avium-intracellulare Infection - microbiology; Mycobacterium Chimaera; Mycobacterium intracellulare; Mycolic Acids - analysis; Nucleic Acid Hybridization; Phylogeny; Polymorphism, Restriction Fragment Length; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; Sequence Analysis, DNA; Sequence Homology; Systematics; Mycobacteriales; Taxonomy; Mycobacteriaceae; Mycobacterium avium; Bacteria; Genetics; Actinomycetes; New species; Species complex
• ISSN: 1466-5026; 1466-5034
• DOI: 10.1099/ijs.0.02777-0

1 Regional Reference Center for Mycobacteria, Microbiology and Virology Laboratory, Careggi Hospital, 50134 Florence, Italy 2 Department of Experimental Pathology, Medical Biotechnologies, Infectivology and Epidemiology, University of Pisa, 56127 Pisa, Italy 3 Department of Preventive Medicine, Autonoma University of Madrid, 28029 Madrid, Spain 4 Microbiology and Virology Laboratory, S. Camillo-Forlanini Hospitals, 00149 Rome, Italy 5 Department of Public Health, University of Florence, 50134 Florence, Italy 6 German Collection of Microorganisms and Cell Cultures, 38124 Braunschweig, Germany 7 Clinical Laboratory, Campo di Marte Hospital, 55100 Lucca, Italy 8 Genetics and Cytogenetics Unit, Careggi Hospital, 50134 Florence, Italy 9 Microbiological and Virological Serum-immunology Laboratory, Careggi Hospital, 50134 Florence, Italy 10 Department of Specialized and Experimental Clinical Medicine, Microbiology Division, University of Bologna, 40138 Bologna, Italy 11 Regional Reference Center for Mycobacteria, S. Bortolo Hospital, 36100 Vicenza, Italy Correspondence Enrico Tortoli e.tortoli{at}libero.it The possibility that the strains included within the Mycobacterium avium complex (MAC), but not belonging either to M. avium or to Mycobacterium intracellulare , may be members of undescribed taxa, has already been questioned by several taxonomists. A very homogeneous cluster of 12 strains characterized by identical nucleotide sequences both in the 16S rDNA and in the 16S–23S internal transcribed spacer was investigated. Similar strains, previously reported in the literature, had been assigned either to the species M. intracellulare on the basis of the 16S rDNA similarity or to the group of MAC intermediates. However, several phenotypical and epidemiological characteristics seem to distinguish these strains from all other MAC organisms. The unique mycolic acid pattern obtained by HPLC is striking as it is characterized by two clusters of peaks, instead of the three presented by all other MAC organisms. All of the strains have been isolated from humans and all but one came from the respiratory tract of elderly people. The clinical significance of these strains, ascertained for seven patients, seems to suggest an unusually high virulence. The characteristics of all the strains reported in the literature, genotypically identical to the ones described here, seem to confirm our data, without reports of isolations from animals or the environment or, among humans, from AIDS patients. Therefore, an elevation of the MAC variant was proposed and characterized here, with the name Mycobacterium chimaera sp. nov.; this increases the number of species included in the M. avium complex. The type strain is FI-01069 T (=CIP 107892 T =DSM 44623 T ). Abbreviations: HMMIS, high molecular mass internal standard; ITS, internal transcribed spacer; LMMIS, low molecular mass internal standard; MAC, Mycobacterium avium complex; MAIS, M. avium–M. intracellulare–Mycobacterium scrofulaceum group; MAIX, M. avium–M. intracellulare cluster X; PRA, PCR restriction enzyme pattern analysis Published online ahead of print on 16 February 2004 as DOI 10.1099/ijs.0.02777-0. The GenBank/EMBL/DDBJ accession number for the 16S rDNA and ITS regions sequence of strain FI-01069 T is AJ548480 . Alignment of the ITS sequevars of MAC, PRA patterns and a table containing the fatty acid content are available as supplementary material in IJSEM Online.