Mycobacterium hassiacum

Description

M. hassiacum is a gram-positive, nonmotile bacteria with partially acid-fast rods. The scotochromogenic colonies are yellow, moist, and slimy when grown at 37 °C. Distinct and drier colonies form when grown at 60 °C.

Physiology

• Aerobic and thermophilic rapid growth on Löwenstein-Jensen medium at a temperature range between 30 °C and 65 °C.
• Growth also occurs on 5% NaCl and MacConkey agar without methyl violet.
• Susceptible to some antibiotics, including streptomycin, ethambutol, cycloserine, ciprofloxacin and clarithromycin.
• Resistant to isoniazid, rifampicin and prothionamide.

Differential characteristics

Like many heat tolerant rapid growers, M. hassiacum has an extended helix 10, due to the insertion of an extra cytosine, and a short helix 18. Phylogenetic clustering algorithms place it either with other thermotolerant rapid growers or in a position close to the slowly growing species Mycobacterium xenopi.

However, it is easy to distinguish from other mycobacteria by its growth at 65 °C and inability to utilise any sugar or citrate. Another key identifying feature is its ability to split benzamide. M. hassiacum can also split urea, nicotinamide, and pyrazinamide.

Pathogenesis

Mycobacterium hassiacum was first isolated from human urine in the German province of Hesse, with the host showing no signs of disease. Another isolation of M. hassiacum from urine was also apathogenic. For these reasons, M. hassiacum has been assigned a Biosafety level 1, meaning it is not known to consistently cause disease in healthy adult humans, and is a minimal hazard to laboratory personnel and the environment.

Type strain

Strain 3849 = CCUG 37519 = CIP 105218 = DSM 44199 = JCM 12690. rDNA sequence accession number: U49401.

References

References

1. (1997). "Mycobacterium hassiacum sp. nov., a new rapidly growing thermophilic mycobacterium". International Journal of Systematic Bacteriology.
2. Tortoli, Enrico. (April 2003). "Impact of Genotypic Studies on Mycobacterial Taxonomy: the New Mycobacteria of the 1990s". Clinical Microbiology Reviews.