The Gram-negative diplococci are pathogenic microbes that infect mammalian mucous membranes, and include the species which causes gonorrhea.

The Gram-negative diplococci Neisseria are pathogenic microbes that infect mammalian mucous membranes, and include the species which causes gonorrhea.

Explanation:

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Bacteria of the genus Neisseria are Gram-negative, with a rounded morphology that are associated in pairs, so they are called diplococci. They are aerobic microorganisms, no more than 1 micrometer in diameter, immobile and not sporulated.

Their biological importance is due to the fact that they cause diseases in humans, such as bacterial meningitis -caused by N. meningitidis- or gonorrhea, associated with  N. gonorrhoeae.

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Germ theory of disease link