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Coccus
 
 
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Cocci (singular - coccus, from the Latin coccinus (scarlet) and derived from the Greek kokkos (berry) ) are any microorganism
Microorganism

A microorganism or microbe is an organism that is microscopic . The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design....
 (usually bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
) whose overall shape is spherical
Sphere

A sphere is a symmetrical geometrical object. In non-mathematical usage, the term is used to refer either to a round ball or to its two-dimensional surface....
 or nearly spherical.






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Arrangement of Cocci Bacteria
Staphylococcus Aureus Gram


Cocci (singular - coccus, from the Latin coccinus (scarlet) and derived from the Greek kokkos (berry) ) are any microorganism
Microorganism

A microorganism or microbe is an organism that is microscopic . The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design....
 (usually bacteria
Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
) whose overall shape is spherical
Sphere

A sphere is a symmetrical geometrical object. In non-mathematical usage, the term is used to refer either to a round ball or to its two-dimensional surface....
 or nearly spherical. Describing a bacterium as a coccus, or sphere, distinguishes it from bacillus
Bacillus (shape)

Although Bacillus, capitalized and Italics, specifically refers to the genus, the word bacillus may also be used to describe any rod-shaped bacterium, and in this sense, bacilli are found in many different taxonomic groups of bacteria....
, or rod. This is the first of many taxonomic traits for identifying and classifying a bacterium according to binomial nomenclature.

Aggregations

Aggregations of coccoid bacteria often occur and these forms have specific names as well; listed here are the basic forms as well as representative bacterial genera
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
:
  • pairs, or diplococci
    Diplococcus

    A diplococcus is a round bacteria that typically occurs in pairs of two joined cells. Examples are Streptococcus pneumoniae, Moraxella catarrhalis, Neisseria gonorrhoeae and Neisseria meningitidis....
     (Neisseria
    Neisseria

    Neisseria is a genus of Gram bacterium included among the proteobacteria, a large group of Gram-negative forms. Neisseria are Diplococcus that resemble coffee beans when viewed microscopically....
    )
  • groups of four or eight known as tetrads or sarcina (Micrococci)
  • bead-like chains, or streptococci (Streptococcus
    Streptococcus

    Streptococcus is a genus of sphere Gram-positive bacterium belonging to the phylum Firmicutes and the lactic acid bacteria group. Cell division occurs along a single Coordinate axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek language st?ept?? streptos, meaning easily bent or twisted,...
    )
  • grapelike clusters, or staphylococci (Staphylococcus
    Staphylococcus

    Staphylococcus is a genus of Gram-positive Bacterium. Under the microscope they appear round , and form in grape-like clusters.The Staphylococcus genus include just thirty-three species....
    )


Clinical significance

Important human pathogen
Pathogen

A pathogen , infectious agent, or germ, is a biological agent that causes disease or illness to its Host .There are several substrates and pathways whereby pathogens can invade a host; the principal pathways have different episodic time frames, but soil contamination has the longest or most persistent potential for harboring...
s caused by coccoid bacteria include staphylococci infections, some types of food poisoning
Food poisoning

Food poisoning refers to the presentation of acute illness due to the ingestion of food. It can lead to infectious diarrhea.The term usually includes:...
, some urinary tract infection
Urinary tract infection

A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Although urine contains a variety of fluids, salts, and waste products, it usually does not have bacteria in it....
s, toxic shock syndrome
Toxic shock syndrome

Toxic shock syndrome is a very rare but potentially fatal illness caused by a Exotoxin. Different bacteriuml toxins may cause toxic shock syndrome, depending on the situation....
, gonorrhea
Gonorrhea

Gonorrhea is caused by the bacterium Neisseria gonorrhoeae and is a common sexually transmitted infection. In the US, its incidence is second only to Chlamydia infection....
, as well as some forms of meningitis
Meningitis

Meningitis is a medical condition caused by inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges....
, throat infections, pneumonia
Pneumonia

Pneumonia is an Inflammation illness of the lung. Frequently, it is described as lung parenchyma/alveolus inflammation and abnormal alveolar filling with fluid ....
s, and sinusitis
Sinusitis

Sinusitis is an inflammation of the paranasal sinuses, which may or may not be as a result of infection, from bacterial, fungus, virus, allergy or autoimmunity issues....
.

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