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Worldwide, 1/3 of the world's population is infected with TB, and over 16 million existing cases of disease and 8 million new cases occur each year. It is an important complication in patients with AIDS.
Countries with the highest TB prevalence are found in Southeast Asia, sub-Saharan Africa, and Eastern Europe, although resurgence is occurring in many developed countries.
Risk factors for TB exposure include:
Risk factors for active TB include:
M. tuberculosis is a slightly curved or straight bacilli. It is aerobic, non-motile, and slow-growing (doubling time 18h).
The bacterium is known as acid-fast due to high concentration of mycolic acids (lipid) in cell wall that withstands decolorization
Most strains grow on relatively simple media; some are fastidiuous and some cannot be cultured.