Viridans streptococci
Viridans streptococci
Viridans streptococci (pronunciation: vɪˈrɪdənz ˌstrɛptəˈkɒkaɪ) are a large group of commensal bacterial species that are either alpha-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), or non-hemolytic. They are a part of the normal microbiota in the human mouth and gut, and can be an opportunistic pathogen.
Etymology
The term "viridans" is derived from the Latin word "vĭrĭdis", which means green. This is in reference to the green coloration these bacteria produce on blood agar plates due to their alpha-hemolytic properties.
Characteristics
Viridans streptococci are Gram-positive, catalase-negative, and facultatively anaerobic. They are not usually pathogenic in healthy individuals, but can cause endocarditis, meningitis, and other infections in individuals with weakened immune systems or damaged heart valves.
Related Terms
- Alpha-hemolytic: A type of hemolysis in which the bacteria partially break down the red blood cells in the agar, producing a green coloration.
- Commensal: An organism that lives on or in a host organism and derives nourishment from the host without benefiting or harming the host.
- Microbiota: The community of microorganisms, including bacteria, archaea, viruses, and fungi, that inhabit a particular environment or habitat.
- Endocarditis: An inflammation of the inner layer of the heart, the endocardium, usually with involvement of the heart valves.
- Meningitis: An acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.
External links
- Medical encyclopedia article on Viridans streptococci
- Wikipedia's article - Viridans streptococci
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