Mycobacterium tuberculosisMycobacteria are aerobic and nonmotile bacteria that are characteristically acid-alcohol fast. Mycobacterium tuberculosis, along with M. bovis, M. africanum, and M. microti all cause the disease known as tuberculosis (TB) and are members of the tuberculosis species complex.
Each member of the TB complex is pathogenic, but M. tuberculosis is pathogenic for humans while M. bovis is usually pathogenic for animals. Mycobacterium tuberculosis, then known as the "tubercle bacillus," was first described on March 24, 1882 by Robert Koch. Mycobacterium tuberculosis is the etiologic agent of tuberculosis in humans. Humans are the only reservoir for the bacterium.
Mycobacterium tuberculosis is known as "acid-fast bacilli" because of their lipid-rich cell wall, which is relatively impermeable to various basic dyes unless the dyes are combined with phenol. Only about 10% of people infected with M tuberculosis ever develop tuberculosis disease. Many of those who suffer TB do so in the first few years following infection, but the bacillus may lie dormant in the body for decades.
Although most initial infections have no symptoms and people overcome them, they may develop fever, dry cough, and chest x-ray abnormalities. Tuberculosis (TB) is the leading cause of death in the world from a bacterial infectious disease. The disease affects 1.8 billion people each year which is equal to one-third of the entire world population.
In the United States Tuberculosis is on the decline. In 2007 a total of 13,293 cases were reported. The TB rate declined to 4.4 cases per 100,000 populations, the lowest recorded rate since national reporting began in 1953. Despite this overall improvement, progress toward tuberculosis elimination has slowed in recent years; the average annual percentage decline in the tuberculosis rate slowed from 7.3% per year during 1993--2000 to 3.8% during 2000--2007. Also, since 1993 there has been a gradual decline in the number of tuberculosis patients with co infection with HIV, and the number of cases of multiple drug-resistant tuberculosis has gradually dropped.
Mycobacterium tuberculosis
