Structure and Physiology
Mycobacterium terrae is an aerobic, nonmotile, rod shaped, acid-fast Gram-positive bacterium. A distinguishing characteristic of mycobacterium is that the cell wall is thicker than many other bacterium. M. terrae is a slow growing species of Mycobacterium and is sometimes referred to as the “radish bacillus” because it was first isolated from radish water.
Transmission and Disease
M. terrae was first injected into guinea pigs and did not cause any symptoms or illness. These test led to the misconception that this strain is nonpathogenic. It was not until M. terrae was isolated from infections causing diseases of the joints, tendons, lungs, gastrointestinal tract, and genitourinary tract that it was considered pathogenic. Humans infected with the bacterium show symptoms of swelling, lesions, inflammation, and mimic the symptoms of osteoarthritis.
M. terrae is used in the laboratory setting to determine disinfection efficiency. Studies have shown that M. terrae, which is not a category 3 pathogen, was slightly more resistant than M. tuberculosis. This makes M. terrae a suitable surrogate for establishing tuberculocidal activity without risking the health of the scientist.
M. terrae grows more quickly than M. bovis, making it an excellent choice for testing during early-stage formulation of tuberculocidal products.
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- Griffiths PA, Babb JR, Fraise AP. Mycobacterium terrae: a potential surrogate for Mycobacterium tuberculosis in a standard disinfectant test. J Hosp Infect. 1998. Mar;38(3):183-92.