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Almost half of the newly described Mycobacterium species are published with synonymous genus names

L Rigouts(1,2) A Goormans(2) H Ipermans(2) S Cogneau(1) B C de Jong(1) C M Meehan()

1:Institute of Tropical Medicine; 2:University of Antwerp; 3:Nottingham Trent University

In 2018, a split of the Mycobacterium genus into 5 new genera was proposed: Mycolicibacterium, Mycolicibacter, Mycolicibacillus, Mycobacteroides, and a revised Mycobacterium. [1] The proposed nomenclature was acknowledged as synonymous for the conservative Mycobacterium genus. This led to confusion, notably within clinical microbiology, as lack of traceable names for pathogens can lead to diagnostic confusion.[2]

We searched the PubMed-NCBI and Google Scholar Search databases for newly described species within these genera, between January 2020 and February 2024.

Twenty-three new species were described, of which only 11 with the genus name “Mycobacterium”, while another 11 were described as “Mycolicibacterium sp” and one as “Mycolicibacter sp”. The choice of genus name was not associated with the journal of publication. The “Mycobacterium” genus name was used in the conservative way, without reference to the new synonyms. In case the new nomenclature would have been applied, only 4 new species would fall in the revised “Mycobacterium” genus, while three would become “Mycolicibacterium sp” and four “Mycolicibacter sp”.

Five of the six new species with probable or documented human clinical relevance were assigned to “Mycobacterium”: four associated with lung disease (M. hubeiense, M. vicinigordonae, M. kiyosense, and M. senriense) and one with skin disease (M. salfingeri). M. salfingeri and M. hubeiense would become “Mycolicibacterium” with the synonymous nomenclature. Also Mycolicibacterium toneyamachuris was associated with pulmonary disease.

Despite expressed concerns from mycobacteriologists, new species are often described using the new nomenclature, also clinically relevant species, which may further confuse clinical microbiologists and diagnostic developers.

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