Mycobacterium heidelbergense

Mycobacterium heidelbergense is a Gram-positive, nonmotile, acid-fast, coccobacilli. It's a species of the phylum actinobacteria (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus mycobacterium.

Description

Dimensions : 0.5-0.8 µm x 2.0-3.0 µm

Colony characteristics

• Smooth, dome-like and nonpigmented colonies on Löwenstein-Jensen media at 35°C (0.5–1 mm in diameter).

Physiology

• Slow growth on Löwenstein-Jensen medium at 35°C within 3–4 weeks.
• Optimal growth at a temperature range from 33°C to 35°C, but also growth at 30°C and 37°C, neither growth at 25°C nor at 45°C.
• Susceptible to isoniazid, rifampicin and ethambutol.
• Resistant to pyrazinamide and cycloserine.

Differential characteristics

• Differentiation from M. malmoense, (bearing a strong phenotypic resemblance to M. heidelbergense), by its wider range of susceptibility to antituberculous drugs, (including isoniazid), and by its inability to grow on Löwenstein-Jensen medium at 25°C.
• Differentiation of M. triplex from M. heidelbergense by its positive nitrate reduction test and by its characteristic HPLC profile (triple-mycolate pattern).

Pathogenesis

• Cervical lymphadenitis in immunocompetent patients.
• Biosafety level not known

Type strain

• First isolated from an immunocompetent paediatric patient with cervical lymphadenitis with recurrent fistula formation, in Heidelberg, Germany.

Strain 2554/91 = ATCC 51253 = CIP 105424 = DSM 44471.

References

• Haas et al. 1997. A new agent of mycobacterial lymphadenitis in children: Mycobacterium heidelbergense sp. nov. J. Clin. Microbiol. 35, 3203-3209.