Species of bacterium
Mycobacterium genavense is a slow-growing species of the phylum Actinomycetota (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus Mycobacterium.
Description
Nonmotile, acid-fast coccobacilli (1.0 µm x 2.0 µm). No formation of spores, capsules or aerial hyphae.
Colony characteristics
Physiology
- Slow, fastidious growth in liquid media within 3–12 weeks at 31 °C, 37 °C and 42 °C, with slightly better growth at 45 °C.
- Primary cultures for isolation require liquid broth media such as BACTEC 12B medium, Middlebrook 7H9 medium.
- Acid broth media such as, BACTEC pyrazinamidase test medium, may facilitate primary isolation.
- No growth on standard solid media like Löwenstein-Jensen, unsupplemented Middlebrook 7H11 or Middlebrook 7H10 media.
- Visible growth on solid Middlebrook 7H11 medium supplemented with MJ after inoculation with a broth culture within 3–9 weeks.
- Susceptible to streptomycin and rifampicin
- Resistant to isoniazid
Differential characteristics
- Differentiation from other slowly growing mycobacteria by its fastidious growth.
- Closely related to M. simiae by evaluation of 16S rDNA sequences.
