Mycobacterium

Mycobacterium is a genus of bacteria with waxy, mycolic-acid-rich cell walls. It includes pathogens that cause tuberculosis and leprosy, alongside many environmental species.

Mycolic acid: Long-chain fatty acids that form a major part of the distinctive outer envelope of mycobacteria. These molecules make the cell surface waxy, help resist chemical damage, and shape staining behavior.
Ziehl–Neelsen stain: A staining method that identifies acid-fast bacteria using carbol fuchsin and acid-alcohol decolorization. It exploits mycobacteria’s ability to retain dye through acid-alcohol treatment.
Tuberculosis: An infectious disease caused primarily by Mycobacterium tuberculosis, usually affecting the lungs. It is the best-known disease caused by a member of this genus.
Multidrug-resistant tuberculosis: Tuberculosis caused by bacteria resistant to at least isoniazid and rifampicin. Resistance in Mycobacterium tuberculosis threatens effective treatment and disease control.
Robert Koch: A German physician and microbiologist who established key methods for linking microbes to disease. His identification of the tuberculosis bacterium transformed understanding of mycobacterial disease.
Acid-fastness: The ability of certain bacteria to retain dyes despite washing with acid-alcohol. Mycobacteria resist decolorization because their cell walls contain abundant mycolic acids.
Mycobacterial cell envelope: The multilayered cell boundary of mycobacteria, including peptidoglycan, arabinogalactan, and a mycolic-acid-rich outer layer. Its unusual architecture underlies permeability barriers and resistance to environmental stress.
Leprosy: A chronic infectious disease caused by Mycobacterium leprae, affecting skin and peripheral nerves. It demonstrates the genus’s ability to cause disease beyond the respiratory tract.
Extensively drug-resistant tuberculosis: A severe form of drug-resistant tuberculosis with resistance to additional key medicines. Its emergence exposes limits in available treatment options.
Koch's postulates: A set of criteria proposed to test whether a microorganism causes a particular disease. Tuberculosis research helped establish these principles, though uncultivable pathogens complicate their application.

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