G

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Gamma interferon




A cytokine that is essential for protective immunity in tuberculosis by enabling macrophages to express their full ability to contain the infection.

Gastric aspiration



The removal of the gastric contents through a tube passed down the oesophagus. This is used to harvest tubercle bacilli that have ascended from the lung to the pharynx and been swallowed overnight. It is used in those patients, particularly children, who do not produce sputum.

Genus



The term used to describe the group of organisms above species. Thus the human tubercle bacillus, Mycobacterium tuberculosis, is just one of a hundred or so named species within the genus Mycobacterium. (NB. By convention, the initial letter of a generic name is capitalised and printed in italics.) See Taxonomy.

Ghon focus



The initial focus of tuberculous infection in the lung.

Gibbus



The angular ‘hunchback’ deformity characteristic of advanced spinal tuberculosis.

Granuloma

This is the basis of the tubercle, or ‘little potato’, which gives the disease its name.  Granulomas are characteristic of chronic infections and consist of a compact aggregate of active macrophages around the infecting agent. In tuberculosis, the granulomas may be of enormous size and often show central ‘caseous’ necrosis.

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