''Staphylococcus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bac ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

in the family

Staphylococcaceae The Staphylococcaceae are a family of Gram-positive bacteria that includes the genus ''Staphylococcus'', noted for encompassing several medically significant pathogens. The five genera ''Jeotgalicoccus'', ''Macrococcus'', ''Nosocomiicoccus' ...

from the order

Bacillales The Bacillales are an order of Gram-positive bacteria, placed within the Bacillota. Representative genera include ''Bacillus'', '' Listeria'' and ''Staphylococcus ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphy ...

. Under the

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

, they appear spherical ( cocci), and form in

grape A grape is a fruit, botanically a berry (botany), berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non-Climacteric (botany), climacteric type of fruit, generally occurring in clusters. The cultivation of ...

-like clusters. ''Staphylococcus'' species are

facultative anaerobic organism A facultative anaerobic organism is an organism that makes Adenosine triphosphate, ATP by aerobic respiration if oxygen is present, but is capable of switching to Fermentation (biochemistry), fermentation if oxygen is absent. Some examples of fa ...

s (capable of growth both aerobically and anaerobically). The name was coined in 1880 by Scottish surgeon and bacteriologist Alexander Ogston (1844–1929), following the pattern established five years earlier with the naming of ''

Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occu ...

''. It combines the prefix "staphylo-" (from grc, σταφυλή, staphylē, bunch of grapes), and suffixed by the Modern (from ). Staphylococcus was one of the leading infections in hospitals and many strains of this bacterium have become antibiotic resistant. Despite strong attempts to get rid of them, staph bacteria stay present in hospitals, where they can infect people who are most at risk of infection. Staphylococcus includes at least 43 species. Of these, nine have two subspecies, one has three subspecies, and one has four subspecies. Many species cannot cause disease and reside normally on the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

and

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...

s of humans and other

animals Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

. ''Staphylococcus'' species have been found to be nectar-inhabiting microbes. They are also a small component of the soil microbiome.

Taxonomy

The taxonomy is based on 16s

rRNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from riboso ...

sequences, and most of the staphylococcal species fall into 11 clusters: # ''S. aureus'' group – ''S. argenteus'', ''S. aureus'', ''S. schweitzeri'', ''S. simiae'' # ''S. auricularis'' group – ''S. auricularis'' # ''S. carnosus'' group – ''S. carnosus'', ''S. condimenti'', ''S. debuckii'', ''S. massiliensis'', ''S. piscifermentans'', ''S. simulans'' # ''S. epidermidis'' group – ''S. capitis'', ''S. caprae'', ''S. epidermidis'', ''S. saccharolyticus'' # ''S. haemolyticus'' group – ''S. borealis'', ''S. devriesei'', ''S. haemolyticus'', ''S. hominis'' # ''S. hyicus-intermedius'' group – ''S. agnetis'', ''S. chromogenes'', ''S. cornubiensis'', ''S. felis'', ''S. delphini'', ''S. hyicus'', ''S. intermedius'', ''S. lutrae'', ''S. microti'', ''S. muscae'', ''S. pseudintermedius'', ''S. rostri'', ''S. schleiferi'' # ''S. lugdunensis'' group – ''S. lugdunensis'' # ''S. saprophyticus'' group – ''S. arlettae'', ''S. caeli'', ''S. cohnii'', ''S. equorum'', ''S. gallinarum'', ''S. kloosii'', ''S. leei'', ''S. nepalensis'', ''S. saprophyticus'', ''S. succinus'', ''S. xylosus'' # ''S. sciuri'' group – ''S. fleurettii'', ''S. lentus'', ''S. sciuri'', ''S. stepanovicii'', ''S. vitulinus'' # ''S. simulans'' group – ''S. simulans'' # ''S. warneri'' group – ''S. pasteuri'', ''S. warneri'' A twelfth group – that of ''S. caseolyticus'' – has now been removed to a new genus, ''

Macrococcus ''Macrococcus'' is a genus of Gram-positive cocci belonging to the family Staphylococcaceae. The genus was created in 1998.Kloos, W. E., D. N. Ballard, C. G. George, J. A. Webster, R. J. Hubner, W. Ludwig, K. H. Schleifer, F. Fiedler, and K. Sch ...

'', the species of which are currently the closest known relatives of ''Staphylococcus''. Two species were described in 2015 – ''

Staphylococcus argenteus ''Staphylococcus argenteus'' are gram-positive cocci from the genus ''Staphylococcus'' which have been isolated from blood culture of a 55-year-old Indigenous Australian female in 2006 in Darwin, Northern Territory, Australia. The species is clos ...

'' and ''

Staphylococcus schweitzeri ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. ''Staphylococcus'' species are facultative ...

'' – both of which were previously considered variants of ''S. aureus''. A new coagulase negative species – ''

Staphylococcus edaphicus ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. ''Staphylococcus'' species are facultativ ...

'' – has been isolated from

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

. This species is probably a member of the ''S. saprophyticus'' group.

Groups

Based on an analysis of orthologous gene content three groups (A, B and C) have been proposed.Coates-Brown R, Moran JC, Pongchaikul P, Darby AC and MJ Horsburgh MJ (2018) "Comparative genomics of ''Staphylococcus'' reveals determinants of speciation and diversification of antimicrobial defense". ''Front Microbiol'' Group A includes ''S. aureus'', ''S. borealis'', ''S. capitis'', ''S. epidermidis'', ''S. haemolyticus'', ''S. hominis'', ''S. lugdunensis'', ''S. pettenkoferi'', ''S. simiae'' and ''S. warneri''. Group B includes ''S. arlettae'', ''S. cohnii'', ''S. equorum'', ''S. saprophyticus'' and ''S. xylosus''. Group C includes ''S. delphini'', ''S. intermedius'' and ''S. pseudintermedius''.

Notes

The ''S. saprophyticus'' and ''S. sciuri'' groups are generally

novobiocin Novobiocin, also known as albamycin or cathomycin, is an aminocoumarin antibiotic that is produced by the actinomycete '' Streptomyces niveus'', which has recently been identified as a subjective synonym for ''S. spheroides'' a member of the clas ...

-resistant, as is ''S. hominis'' subsp. ''novobiosepticus''. Members of the ''S. sciuri'' group are

oxidase In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen ...

-positive due to their possession of the enzyme

cytochrome c oxidase The enzyme cytochrome c oxidase or Complex IV, (was , now reclassified as a translocasEC 7.1.1.9 is a large transmembrane protein complex found in bacteria, archaea, and mitochondria of eukaryotes. It is the last enzyme in the respiratory el ...

. This group is the only clade within the staphylococci to possess this gene. The ''S. sciuri'' group appears to be the closest relations to the genus ''

''. ''S. pulvereri'' has been shown to be a junior synonym of ''S. vitulinus''. Within these clades, the ''S. haemolyticus'' and ''S. simulans'' groups appear to be related, as do the ''S. aureus'' and ''S. epidermidis'' groups. ''S. lugdunensis'' appears to be related to the ''S. haemolyticus'' group. ''S. petrasii'' may be related to ''S. haemolyticus'', but this needs to be confirmed. The taxonomic position of ''S. lyticans'', ''S. pettenkoferi'', ''S. petrasii'', and ''S. pseudolugdunensis'' has yet to be clarified. The published descriptions of these species do not appear to have been validly published.

Biochemical identification

Assignment of a strain to the genus ''Staphylococcus'' requires it to be a

coccus A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape. Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spiral ( of w ...

that forms clusters, has an appropriate

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

structure (including

peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid Cell wall#Bacterial_cell_walls, cell wall (murein sac ...

type and teichoic acid presence) and G + C content of DNA in a range of 30–40 mol%. ''Staphylococcus'' species can be differentiated from other aerobic and facultative anaerobic, Gram-positive cocci by several simple tests. ''Staphylococcus'' species are facultative anaerobes (capable of growth both aerobically and anaerobically). All species grow in the presence of bile salts. All species of ''Staphylococcus aureus'' were once thought to be coagulase-positive, but this has since been disproven. Growth can also occur in a 6.5% NaCl solution. On Baird-Parker medium, ''Staphylococcus'' species grow fermentatively, except for ''S. saprophyticus'', which grows oxidatively. ''Staphylococcus'' species are resistant to

bacitracin Bacitracin is a polypeptide antibiotic. It is a mixture of related cyclic peptides produced by '' Bacillus licheniformis'' bacteria, that was first isolated from the variety "Tracy I" ( ATCC 10716) in 1945. These peptides disrupt Gram-positive ...

(0.04 U disc: resistance = < 10 mm zone of inhibition) and susceptible to furazolidone (100 μg disc: resistance = < 15 mm zone of inhibition). Further biochemical testing is needed to identify to the species level.

Coagulase production

One of the most important phenotypical features used in the classification of staphylococci is their ability to produce

coagulase Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of '' Staphylococcus'' isolates. Importantly, '' S. aureu ...

, an enzyme that causes blood clot formation. Seven species are currently recognised as being coagulase-positive: ''S. aureus'', ''S. delphini'', ''S. hyicus'', ''S. intermedius'', ''S. lutrae'', ''S. pseudintermedius'', and ''S. schleiferi'' subsp. ''coagulans''. These species belong to two separate groups – the ''S. aureus'' (''S. aureus'' alone) group and the ''S. hyicus-intermedius'' group (the remaining five). An eighth species has also been described – ''Staphylococcus leei'' – from patients with

gastritis Gastritis