Mycobacterium heidelbergense

Mycobacterium heidelbergense

Description
Gram-positive, and nonmotile acid-fast coccobacilli (0.5-0.8µm x 2.0-3.0µm).

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
Strain 2554/91 = ATCC 51253 = CIP 105424 = DSM 44471.
 * First isolated from a immunocompetent paediatric patient with cervical lymphadenitis with recurrent fistula formation, in Heidelberg, Germany.