The name was coined in 1880 by Scottish surgeon and bacteriologistAlexander Ogston (1844–1929), following the pattern established five years earlier with the naming ofStreptococcus.[1] It combines the prefix "staphylo-" (fromAncient Greek:σταφυλή,romanized: staphylē,lit. 'bunch of grapes'[2]), and suffixed by theNew Latin:coccus,lit. 'spherical bacterium' (from Ancient Greek:κόκκος,romanized: kókkos,lit. 'grain, seed, berry'[3]).
Staphylococcus was one of the leading infections in hospitals and many strains of this bacterium have becomeantibiotic 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.[4]
Staphylococcus includes at least 44 species. Of these, nine have twosubspecies, one has three subspecies, and one has four subspecies.[5] Many species cannot cause disease and reside normally on theskin andmucous membranes of humans and otheranimals.Staphylococcus species have been found to benectar-inhabiting microbes.[6] They are also a small component of thesoil microbiome.[7]
The taxonomy is based on 16srRNA sequences,[8] 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 ofS. caseolyticus – has now been removed to a new genus,Macrococcus, the species of which are currently the closest known relatives ofStaphylococcus.[9]
A new coagulase negative species –Staphylococcus edaphicus – has been isolated fromAntarctica.[11] This species is probably a member of theS. saprophyticus group.
TheS. saprophyticus andS. sciuri groups are generallynovobiocin-resistant, as isS. hominis subsp.novobiosepticus.
Members of theS. sciuri group areoxidase-positive due to their possession of the enzymecytochrome c oxidase. This group is the only clade within the staphylococci to possess this gene.
TheS. sciuri group appears to be the closest relations to the genusMacrococcus.
S. pulvereri has been shown to be a junior synonym ofS. vitulinus.[13]
Within these clades, theS. haemolyticus andS. simulans groups appear to be related, as do theS. aureus andS. epidermidis groups.[14]
S. lugdunensis appears to be related to theS. haemolyticus group.
S. petrasii may be related toS. haemolyticus, but this needs to be confirmed.
The taxonomic position ofS. lyticans,S. petrasii, andS. pseudolugdunensis has yet to be clarified. The published descriptions of these species do not appear to have been validly published.
Assignment of a strain to the genusStaphylococcus requires it to be aGram-positivecoccus[15] that forms clusters, has an appropriatecell wall structure (includingpeptidoglycan 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.[15]Staphylococcus species are facultativeanaerobes (capable of growth both aerobically and anaerobically).[15] All species grow in the presence ofbile salts.
All strains ofStaphylococcus aureus were once thought to be coagulase-positive, but this has since been disproven.[16][17][18]
Growth can also occur in a 6.5% NaCl solution.[15] OnBaird-Parker medium,Staphylococcus species grow fermentatively, except forS. saprophyticus, which grows oxidatively.Staphylococcus species are resistant tobacitracin (0.04 U disc: resistance = < 10 mm zone of inhibition) and susceptible tofurazolidone (100 μg disc: resistance = < 15 mm zone of inhibition). Further biochemical testing is needed to identify to the species level.
One of the most important phenotypical features used in the classification of staphylococci is their ability to producecoagulase, an enzyme that causesblood clot formation.
Seven species are currently recognised as being coagulase-positive:S. aureus,S. delphini,S. hyicus,S. intermedius,S. lutrae,S. pseudintermedius, andS. schleiferi subsp.coagulans. These species belong to two separate groups – theS. aureus (S. aureus alone) group and theS. hyicus-intermedius group (the remaining five).
An eighth species has also been described –Staphylococcus leei – from patients withgastritis.[19]
S. aureus is coagulase-positive, meaning it produces coagulase. However, while the majority ofS. aureus strains are coagulase-positive, some may be atypical in that they do not produce coagulase.S. aureus iscatalase-positive (meaning that it can produce the enzyme catalase) and able to converthydrogen peroxide (H2O2) to water and oxygen, which makes the catalase test useful to distinguish staphylococci fromenterococci andstreptococci.
S. pseudintermedius inhabits and sometimes infects the skin of domestic dogs and cats. This organism, too, can carry the genetic material that imparts multiple bacterial resistance. It is rarely implicated in infections in humans, as azoonosis.
Common abbreviations for coagulase-negative staphylococci are CoNS, CNS, or CNST.[20] TheAmerican Society for Microbiology abbreviates coagulase-negative staphylococci as "CoNS".
The firstS. aureusgenomes to be sequenced were those of N315 and Mu50, in 2001. Many more completeS. aureus genomes have been submitted to the public databases, making it one of the most extensively sequenced bacteria. The use of genomic data is now widespread and provides a valuable resource for researchers working withS. aureus. Whole genome technologies, such as sequencing projects andmicroarrays, have shown an enormous variety ofS. aureus strains. Each contains different combinations of surface proteins and differenttoxins. Relating this information to pathogenic behaviour is one of the major areas of staphylococcal research. The development of molecular typing methods has enabled the tracking of different strains ofS. aureus. This may lead to better control of outbreak strains. A greater understanding of how the staphylococci evolve, especially due to the acquisition of mobile genetic elements encoding resistance and virulence genes is helping to identify new outbreak strains and may even prevent their emergence.[21]
The widespread incidence ofantibiotic resistance across various strains ofS. aureus, or across different species ofStaphylococcus has been attributed tohorizontal gene transfer of genes encoding antibiotic/metal resistance and virulence. A recent study demonstrated the extent of horizontal gene transfer amongStaphylococcus to be much greater than previously expected, and encompasses genes with functions beyond antibiotic resistance and virulence, and beyond genes residing within themobile genetic elements.[22]
Unknown variety ofStaphylococcus,Gram-stained – numbered ticks on the scale are 11 μm apart
Members of the genusStaphylococcus frequently colonize the skin and upper respiratory tracts of mammals and birds and also inmarine sponge.[15] Marine sponge associatedStaphylococcus species are highly salt tolerant.[15] Some species specificity has been observed in host range, such that theStaphylococcus species observed on some animals appear more rarely on more distantly related host species.[23]Some of the observed host specificity includes:
It is said that anyone can develop a staph infection, although certain groups of people are at greater risk, including people with chronic conditions such as diabetes, cancer, vascular disease, eczema, lung disease, and people who inject drugs. In healthcare facilities, the risk of more serious staph infection is higher because many patients have weakened immune systems or have undergone procedures. In healthcare, the risk of more serious staph infection is higher for patients in intensive care units (ICUs), patients who have undergone certain types of surgeries and patients with medical devices inserted in their bodies.[25]
Staphylococcus aureus has emerged as a leading agent ofsepsis. It facilitates factors such as tissue adhesion, immune evasion, and host cell injury. In the bloodstream, these factors cause inflammation, impair immune cell function, alter coagulation, and compromise vascular integrity. When left untreated,S. aureus triggers pathophysiologic disturbances that are further amplified by the host inflammatory response, culminating in the severe clinical manifestations of sepsis andseptic shock.[26]
Staphylococcus can cause a wide variety of diseases in humans and animals through either toxin production or penetration. Staphylococcal toxins are a common cause of food poisoning, for they can be produced by bacteria growing in improperly stored food items. The most commonsialadenitis is caused by staphylococci, as bacterial infections.[27] Staphylococci break downleucine intoisovaleric acid, the main odor of foot odor.[28]
^Jin M, Rosario W, Watler E, Calhoun DH (March 2004). "Development of a large-scale HPLC-based purification for the urease fromStaphylococcus leei and determination of subunit structure".Protein Expression and Purification.34 (1):111–7.doi:10.1016/j.pep.2003.10.012.PMID14766306.
^Stevens D, Cornmell R, Taylor D, Grimshaw SG, Riazanskaia S, Arnold DS, Fernstad SJ, Smith AM, Heaney LM, Reynolds JC, Thomas CL, Harker M. Spatial variations in the microbial community structure and diversity of the human foot is associated with the production of odorous volatiles. FEMS Microbiol Ecol. 2015 Jan;91(1):1-11. doi: 10.1093/femsec/fiu018. Epub 2014 Dec 8. PMID: 25764539.
