# Taxonomic landscape of the Mycobacterium “Fortuitum-Vaccae” clade: a genome study

## TL;DR

This study maps the complex taxonomy of the Mycobacterium Fortuitum-Vaccae clade using genome data, revealing new species and aiding infection diagnosis.

## Contribution

A genome-based taxonomic update of the FVC clade, identifying 86 new taxa and resolving a synonym pair.

## Key findings

- The FVC clade contains 106 species, including 16 previously unclassified ones like M. syngnathidarum.
- 86 new genomospecies and one new synonym pair (M. murale and M. tokaiense) were identified.
- The clade is divided into eight distinct subclades based on core-protein phylogenomic trees.

## Abstract

The Mycobacterium “Fortuitum-Vaccae” clade (FVC) contains many rapid-growing species and is increasingly reported in human infections globally. However, the clade’s taxonomic composition and the exact association with human infections remain to be explored.

In this study, we conducted a comprehensive genome-based analysis of the FVC, aiming to update its taxonomy and identify new taxa. We compiled a dataset of 298 Mycobacterium species using public databases, ultimately including 222 type strain genomes for phylogenomic analysis

This revealed 106 species within the FVC. Subsequent curation of 11,534 public Mycobacterium identified 557 belonging to the FVC, from which we uncovered 86 new taxa (genomospecies) and resolved one new synonym pair. We reconstructed three core-protein phylogenomic trees and found the FVC comprising eight distinct subclades. Our analysis unveiled a remarkably complicated taxonomic landscape within the clade, encompassing 106 known species, among which 16 species, such as M. syngnathidarum and M. yunnanensis, have not previously been classified within the FVC. We detected a pair of synonyms: M. murale is a heterotypic synonym of M. tokaiense.

These findings highlight the remarkable taxonomic diversity within the FVC. The updated taxonomy and the curated database of genomes allow precise species identification in diagnostics, clinical reporting, epidemiological surveillance, and future studies on the ecology and pathogenesis. Accurate identification may uncover the disease spectrum, clinical manifestation, and prognosis of infections by individual FVC species, guiding countermeasures.