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Examples of Cocci Bacteria

Bacteria are unicellular prokaryotic microorganism and often cause human and animal disease such as Leptospira bacteria cause livestock disease. 
Whereas some bacteria such as actinomycetes produce antibiotics like streptomycin and nocardicin and some live symbiotically in the guts of animals or on the roots of certain plants and converting nitrogen into a usable form.

There are more than thousands of species of bacteria on earth, so a variety of characteristics are used to classify them like their visual characteristics or laboratory tests or number and location of flagella. 
On the basis of the bacterium's shape and cell arrangement, bacteria can be classified into three categories; cocci, bacilli, and spirilla.
•    Cocci are round cells and can exist singly or in pairs. The single cell of cocci is known as coccus.
•    Bacilli are rod-shaped bacteria and single cell is known as bacillus. 
The length of a cell depends upon age or environmental conditions.  They can also occur singly or in pairs, or in chains. For examples; coliform bacteria.
•    Spirilla bacteria have gently curved shape or corkscrew-like spiral shape. The single cell is called as spirillum. 

Cocci bacteria can be oval, elongated, or flattened on one side. 
Sometimes they may remain attached after cell division and often used to help identify certain cocci. 
The pair of Cocci is called as diplococcic (Neisseria) while the chain of Cocci is known as streptococci (Streptococcus). 
When Cocci divide in two planes and remain in groups of four, it is known as tetrads. 
Similarly Cocci which divide in three planes and remain in groups cube like groups of eight are known as sarcinae (Micrococci). 
One more examples of Cocci are staphylococci (Staphylococcus) which divide in multiple planes and form grape like clusters or sheets.
Fig: Type of Cocci bacteria
Some common examples of cocci bacteria with their morphology are as follows;
           Name                              Morphology                            Gram Stain

1.        Staph aureus                    clusters/tetrads                        Gram-Positive Cocci
2.        S. epidermidis                  clusters                                   Gram-Positive Cocci
4.        S. saphrophyticus            clusters                                    Gram-Positive Cocci 
5.        S. haemolyticus               clusters                                     Gram-Positive Cocci
6.        S. hominis                        tetrads and clusters                   Gram-Positive Cocci
7.        S. capitis                                                                          Gram-Positive Cocci
8.        S. schleiferi                                                                      Gram-Positive Cocci
9.        S. warneri                                                                        Gram-Positive Cocci
10.      S. lugdenenis                                                                 Gram-Positive Cocci
11.      Strep pyrogenes (gr. A)    chains                                      Gram-Positive Cocci
12.      S. agalactiae (gr. B)        chains                                          Gram-Positive Cocci
13.       E. faecalis                     clusters                                    Gram-Positive Cocci
14.       E. faecium                                                                    Gram-Positive Cocci
15.       Enterococci (other)         chains                                      Gram-Positive Cocci
16.       S. pneumoniae               lancet shaped diplococci,          Gram-Positive Cocci
17.       S. mutans group             chains, or short rods                 Gram-Positive Cocci
18.       S. salivarus group                                                         Gram-Positive Cocci
19.       S. sanguis group                                                          Gram-Positive Cocci
20.       S. mitis group                                                              Gram-Positive Cocci
21.       S. angiosus group          chains                                    Gram-Positive Cocci
22.       A. adiacens                                                                 Gram-Positive Cocci
23.       S. milleri                                                                     Gram-Positive Cocci
24.       S. bovis                        chains                                    Gram-Positive Cocci
25.       N. gonorrhea                diplococci                                Gram-Negative Cocci
26.       N. meningitides            diplococci                                Gram-Negative Cocci