Mycobacterium tuberculosis | bacterium | Britannica (original) (raw)
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affected by pasteurization
In pasteurization …to be necessary to destroy Mycobacterium tuberculosis and other, more heat-resistant, non-spore-forming, disease-causing microorganisms found in milk. The treatment also destroys most of the microorganisms that cause spoilage and so prolongs the storage time of food. Read More
antibiotics
In antibiotic: The first antibiotics …unaffected by penicillin was the tubercle bacillus (Mycobacterium tuberculosis). This organism, however, turned out to be highly sensitive to streptomycin, an antibiotic that was isolated from Streptomyces griseus in 1943. As well as being dramatically effective against tuberculosis, streptomycin demonstrated activity against many other kinds of bacteria, including the Read More
In antibiotic resistance Enterococcus, and multidrug-resistant Mycobacterium tuberculosis (MDR-TB), which is resistant to two tuberculosis drugs, isoniazid and rifampicin. MDR-TB is particularly dangerous because it can give rise to extensively drug-resistant M. tuberculosis (XDR-TB), which requires aggressive treatment using a combination of five different drugs. Read More
In Mycobacterium …most important species of which, M. tuberculosis and M. leprae, cause tuberculosis and leprosy, respectively, in humans. M. bovis causes tuberculosis in cattle and in humans. Some mycobacteria are saprophytes (i.e., they live on decaying organic matter), and others are obligate parasites. Most are found in soil and water in… Read More
In tuberculosis …caused by the tubercle bacillus, Mycobacterium tuberculosis. In most forms of the disease, the bacillus spreads slowly and widely in the lungs, causing the formation of hard nodules (tubercles) or large cheeselike masses that break down the respiratory tissues and form cavities in the lungs. Blood vessels also can be… Read More
diagnosis by tuberculin test
In tuberculin test …substance from the tuberculosis-causing bacillus, Mycobacterium tuberculosis, first discovered and extracted by Robert Koch in 1890. When the test is positive, a region of swelling 10 mm (0.4 inch) or greater in diameter, usually accompanied by redness, occurs within 48 hours at the site of injection. A positive reaction indicates… Read More
discovery by Koch
In Robert Koch: Studies of tuberculosis and cholera of Robert Koch …of staining, Koch discovered the tubercle bacillus and established its presence in the tissues of animals and humans suffering from the disease. A fresh difficulty arose when for some time it proved impossible to grow the organism in pure culture. But eventually Koch succeeded in isolating the organism in a… Read More
reproduction rate
In bacteria: Growth of bacterial populations …20 minutes; and the slow-growing Mycobacterium tuberculosis has a generation time in the range of 12 to 16 hours. Some researchers have suggested that certain bacteria populations living deep below Earth’s surface may grow at extremely slow rates, reproducing just once every several thousand years. The composition of the growth… Read More
tuberculin-type hypersensitivity
In immune system disorder: Tuberculin-type hypersensitivity …the causative agent of tuberculosis, Mycobacterium tuberculosis. (A previously infected individual would harbour reactive T cells in the blood.) In this test, small amounts of protein extracted from the mycobacterium are injected into the skin. If reactive T cells are present—i.e., the test is positive—redness and swelling appear at the… Read More
