# Staphylococcus

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 anaerobic organisms (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. It combines the prefix "staphylo-" (from Ancient Greek: σταφυλή, romanized: staphylē, lit. 'bunch of grapes'), and suffixed by the New Latin: coccus, lit. 'spherical bacterium' (from Ancient Greek: κόκκος, romanized: kókkos, lit. 'grain, seed, berry').
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, staphylococcus bacteria stay present in hospitals, where they can infect people who are most at risk of infection.
Staphylococcus includes at least 44 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 and mucous membranes of humans and other animals. 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 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, the species of which are currently the closest known relatives of Staphylococcus.
Two species were described in 2015 – Staphylococcus argenteus and Staphylococcus schweitzeri – both of which were previously considered variants of S. aureus.
A new coagulase negative species – Staphylococcus edaphicus – has been isolated from Antarctica. 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.
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.