What is "mycobacterium tuberculosis"

Tubercle \Tu"ber*cle\, n. [L. tuberculum, dim. of tuber: cf. F. tubercule, OF. also tubercle. See Tuber.]

1. A small knoblike prominence or excrescence, whether natural or morbid; as, a tubercle on a plant; a tubercle on a bone; the tubercles appearing on the body in leprosy.

2. (Med.) A small mass or aggregation of morbid matter; especially, the deposit which accompanies scrofula or phthisis. This is composed of a hard, grayish, or yellowish, translucent or opaque matter, which gradually softens, and excites suppuration in its vicinity. It is most frequently found in the lungs, causing consumption.

   Tubercle bacillus (Med.), a minute vegetable organism ( Mycobacterium tuberculosis, formerly Bacillus tuberculosis, and also called Koch's bacillus) discovered by Koch, a German physician, in the sputum of consumptive patients and in tuberculous tissue. It is the causative agent of tuberculosis.

Tuberculosis \Tu*ber`cu*lo"sis\, n. [NL. See Tubercle.] (Med.) A constitutional disease caused by infection with Mycobacterium tuberculosis (also called the Tubercle bacillus), characterized by the production of tubercles in the internal organs, and especially in the lungs, where it constitutes the most common variety of pulmonary phthisis (consumption). The Mycobacteria are slow-growing and without cell walls, and are thus not affected by the beta-lactam antibiotics; treatment is difficult, usually requiring simultaneous administration of multiple antibiotics to effect a cure. Prior to availability of antibiotic treatment, the cure required extensive rest, for which special sanatoriums were constructed.

Mycobacterium tuberculosis is an obligate pathogenic bacterial species in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface (primarily due to the presence of mycolic acid), which makes the cells impervious to Gram staining; M. tuberculosis can appear Gram-negative and Gram-positive in clinical settings. The Ziehl-Neelsen stain, or acid-fast stain, is used instead. The physiology of M. tuberculosis is highly aerobic and requires high levels of oxygen. Primarily a pathogen of the mammalian respiratory system, it infects the lungs. The most frequently used diagnostic methods for tuberculosis are the tuberculin skin test, acid-fast stain, and chest radiographs.

The M. tuberculosis genome was sequenced in 1998.