Staphylococcus is a genus of
Gram-positiveGram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...
bacteria. Under the
microscopeA microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
they appear round (cocci), and form in
grapeA grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...
-like clusters.
The Staphylococcus
genusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
includes at least forty species. Of these, nine have two subspecies and one has three subspecies. Most are harmless and reside normally on the
skin-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
and mucous membranes of humans and other organisms. Found worldwide, they are a small component of soil microbial flora.
Taxonomy
The taxonomy is based on 16s rRNA sequences and most of the staphylococcal species fall into 11 clusters:
S. aureus group – S. aureus, S. simiae
S. auricularis group – S. auricularis
S. carnosus group – S. carnosus, S. condimenti, S. massiliensis, S. piscifermentans, S. simulans
S. epidermidis group – S. capitis, S. caprae, S. epidermidis, S. saccharolyticus
S. haemolyticus group – S. devriesei, S. haemolyticus, S. hominis
S. hyicus-intermedius group – S. chromogenes, 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. 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 moved to a new genus
MacrococcusMacrococcus is a genus of Gram positive cocci belonging to the family Staphylococcaceae. The genus was created in 1998-History:The first recognised species in this genus was initially named Micrococcus caseolyticus by Evans in 1916. It was then renamed Staphylococcus caseolyticus by Schleifer et...
the species of which are currently the closest known relatives of the Staphylococci.
Subspecies
S. aureus subsp. aureus
S. aureus subsp. anaerobius
S. capitis subsp. capitis
S. capitis subsp. urealyticus
S. carnosus subsp. carnosus
S. carnosus subsp. utilis
S. cohnii subsp. cohnii
S. cohnii subsp. urealyticus
S. equorum subsp. equorum
S. equorum subsp. linens
S. hominis subsp. hominis
S. hominis subsp. novobiosepticus
S. saprophyticus subsp. bovis
S. saprophyticus subsp. saprophyticus
S. schleiferi subsp. coagulans
S. schleiferi subsp. schleiferi
S. sciuri subsp. carnaticus
S. sciuri subsp. rodentium
S. sciuri subsp. sciuri
S. succinus subsp. casei
S. succinus subsp. succinus
Biochemical identification
Assignment of a strain to the genus Staphylococcus requires that it is a
Gram-positiveGram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...
coccusCoccus can be used to describe any bacterium that has a spherical shape. It is one of the three distinct types of bacteria shapes, the other two being bacillus and spirillum cells...
that forms clusters, produces
catalaseCatalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...
, has an appropriate
cell wallThe cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...
structure (including
peptidoglycanPeptidoglycan, also known as murein, is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of bacteria , forming the cell wall. The sugar component consists of alternating residues of β- linked N-acetylglucosamine and N-acetylmuramic acid...
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 spp. are facultative anaerobes (capable of growth both aerobically and anaerobically). All species grow in the presence of bile salts and all are catalase positive. Growth can also occur in a 6.5% NaCl solution. On
Baird Parker MediumBaird–Parker agar is a type of agar used for the selective isolation of gram-positive Staphylococci species. It contains lithium chloride and tellurite to inhibit the growth of alternative microbial flora, while the included pyruvate and glycine promote the growth of Staphylococci. Staphylococcus...
Staphylococcus spp. grow fermentatively, except for S. saprophyticus which grows oxidatively. Staphylococcus spp. are resistant to
bacitracinBacitracin is a mixture of related cyclic polypeptides produced by organisms of the licheniformis group of Bacillus subtilis var Tracy, isolation of which was first reported in 1945....
(0.04 U disc: resistance = <10mm zone of inhibition) and susceptible to
furazolidoneFurazolidone is a nitrofuran antibacterial. It is marketed by Roberts Laboratories under the brand name Furoxone and by GlaxoSmithKline as Dependal-M.-Uses:It is used to treat diarrhoea and enteritis caused by bacteria or protozoan infections....
(100μg disc: resistance = <15mm zone of inhibition). Further biochemical testing is needed to identify down to the species level.
Coagulase production
One of the most important phenotypical features used in the classification of staphylococci is their ability to produce
coagulaseCoagulase is a protein 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. Coagulase negativity excludes S. aureus. That is to say, S...
, an enzyme that causes blood clot formation.
Six 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).
A seventh species has also been described – Staphylococcus leei – from patients with gastritis.
S. aureusStaphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
(formerly called Staphylococcus pyogenes) is coagulase-positive, meaning that it produces coagulase. However, while the majority of S. aureus are coagulase-positive, some may be atypical in that they do not produce coagulase. S aureus is
catalaseCatalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...
-positive (meaning that it can produce the enzyme catalase) and able to convert
hydrogen peroxideHydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
(H
2O
2) to water and oxygen, which makes the catalase test useful to distinguish Staphylococci from
EnterococciEnterococcus is a genus of lactic acid bacteria of the phylum Firmicutes. Enterococci are Gram-positive cocci that often occur in pairs or short chains, and are difficult to distinguish from streptococci on physical characteristics alone. Two species are common commensal organisms in the...
and
StreptococciStreptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...
.
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 a
zoonosisA zoonosis or zoonoseis any infectious disease that can be transmitted from non-human animals to humans or from humans to non-human animals . In a study of 1415 pathogens known to affect humans, 61% were zoonotic...
.
S. epidermidisStaphylococcus epidermidis is one of thirty-three known species belonging to the genus Staphylococcus. It is part of human skin flora, and consequently part of human flora. It can also be found in the mucous membranes and in animals. Due to contamination, it is probably the most common species...
, a
coagulaseCoagulase is a protein 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. Coagulase negativity excludes S. aureus. That is to say, S...
-negative staphylococcus species, is a commensal of the
skin-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, but can cause severe infections in
immune-suppressedImmunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other...
patients and those with central venous catheters.
S. saprophyticusStaphylococcus saprophyticus is a coagulase-negative species of Staphylococcus bacteria. S. saprophyticus is often implicated in urinary tract infections. S. saprophyticus is resistant to the antibiotic novobiocin, a characteristic that is used in laboratory identification to distinguish it from S...
, another
coagulaseCoagulase is a protein 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. Coagulase negativity excludes S. aureus. That is to say, S...
-negative species that is part of the normal
vaginal floraThe bacteria that colonize the vagina, collectively referred to as the vaginal microbiome, were discovered by the German gynecologist Albert Döderlein in 1892. The amount and type of bacteria present have significant implications for a woman's overall health...
, is predominantly implicated in genitourinary tract infections in sexually-active young women.
In recent years, several other Staphylococcus species have been implicated in human infections, notably
S. lugdunensisStaphylococcus lugdunensis is a coagulase-negative member of the genus Staphylococcus, consisting of Gram-positive bacteria with spherical cells that appear in clusters.-History:...
, S. schleiferi, and
S. capraeStaphylococcus caprae is a Gram positive, coccus bacteria and a member of the genus Staphylococcus. S. caprae is coagulase-negative. It was originally isolated from goats but members of this species have also been isolated from human samples.-Clinical importance:S...
.
Common abbreviations for coagulase-negative staphylococcus species are CoNS and CNS.
Genomics and molecular biology
The first S. aureus
genomeIn modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s to be sequenced were those of N315 and Mu50 in 2001. Many more complete S. aureus genomes have been submitted to the public
databaseA database is an organized collection of data for one or more purposes, usually in digital form. The data are typically organized to model relevant aspects of reality , in a way that supports processes requiring this information...
s, making S. aureus one of the most extensively sequenced bacteria. The use of genomic data is now widespread and provides a valuable resource for researchers working with S. aureus. Whole genome technologies such as sequencing projects and
microarrayA microarray is a multiplex lab-on-a-chip. It is a 2D array on a solid substrate that assays large amounts of biological material using high-throughput screening methods.Types of microarrays include:...
s have shown there is an enormous variety of S. aureus strains. Each contains different combinations of surface proteins and different
toxinA toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s. 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 of S. 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.
The widespread of antibiotic resistance across various strains of S. aureus, or across different species of Staphylococcus has been attributed to
horizontal gene transferHorizontal gene transfer , also lateral gene transfer , is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism...
of genes encoding antibiotic/metal resistance and virulence. A recent study demonstrates the extent of
horizontal gene transferHorizontal gene transfer , also lateral gene transfer , is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism...
among Staphylococcus to be much greater than one previously expected, and encompasses genes with functions beyond antibiotic resistance and virulence, and beyond genes residing within the
mobile genetic elementsMobile genetic elements are a type of DNA that can move around within the genome. They include:*Transposons **Retrotransposons**DNA transposons**Insertion sequences*Plasmids...
.
Various strains of Staphylococcus are available from biological research centres such as the
National Collection of Type CulturesNational Collection of Type Cultures is one of the four organizations that constitutes the HPA Culture Collections. It is a non-profit culture collection repository located in UK. NCTC maintains over 5000 bacterial cultures, over 100 mycoplasmas and more than 500 plasmids, host strains,...
(NCTC).
Host range
Members of the genus Staphylococcus frequently colonize the skin and upper respiratory tracts of mammals and birds. Some species specificity has been observed in host range, such that the Staphylococcus species observed on some animals appear more rarely on more distantly related host species.
Some of the observed host specificity includes:
S. arlattae –
chickenThe chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s,
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. auricularis –
deerDeer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
,
dogThe domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, humans
S. capitis – humans
S. caprae –
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s, humans
S. cohnii –
chickenThe chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
s, humans
S. delphini –
dolphinDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s
S. devriesei –
cattleCattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
S. epidermiditis – humans
S. equorum –
horseThe horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s
S. felis –
catThe cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s
S. fleurettii –
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. gallinarum –
chickenThe chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...
,
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s,
pheasantPheasants refer to some members of the Phasianinae subfamily of Phasianidae in the order Galliformes.Pheasants are characterised by strong sexual dimorphism, males being highly ornate with bright colours and adornments such as wattles and long tails. Males are usually larger than females and have...
s
S. haemolyticus – humans, Cercocebus, Erythrocebus,
LemurLemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...
,
MaccaMacca is a common nickname in English speaking countries of Anglo-Saxon heritage for somebody whose surname begins with the Gaelic prefix Mac or Mc .People frequently referred to as Macca include:* Sir Paul McCartney, musician...
, Microcebus,
PanChimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
S. hyicus –
pigA pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
s
S. leei – humans
S. lentus –
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s,
rabbitRabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s, sheep
S. lugdunensis – humans,
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. lutrae –
otterThe Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....
s
S. microti – voles (Microtus arvalis)
S. nepalensis –
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. pasteuri – humans,
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. pettenkoferi – humans
S. pseudintermedius –
dogThe domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s
S. rostri –
pigA pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
s
S. schleiferi – humans
S. sciuri – humans,
dogThe domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s,
goatThe domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s
S. simiae – South American squirrel monkeys (Saimiri sciureus)
S. simulans – humans
S. warneri – humans, Cercopithecoidea,
PongidaePongidae is a taxonomical family which is no longer in use.*Originally, until the last few years of the 20th century, Pongidae comprised all the extant species in the current family Hominidae, excluding Homo sapiens and sometimes including the family Hylobatidae .*Currently pongid may refer to the...
S. xylosus – humans
Clinical
Staphylococcus can cause a wide variety of diseases in humans and other animals through either toxin production or penetration. Staphylococcal toxins are a common cause of food poisoning, as it can grow in improperly-stored food items.
The most common
sialadenitisSialadenitis is inflammation of a salivary gland. It may be subdivided temporally into acute, chronic and recurrent forms.Alternate spelling:Sialoadenitis-Acute Form:Predisposing factors:* decreased flow * poor oral hygiene...
is caused by staphylococcus, as bacterial infection.
See also
- MRSA
- Vancomycin-resistant Staphylococcus aureus
Vancomycin-resistant Staphylococcus aureus refers to strains of Staphylococcus aureus that have become resistant to the glycopeptide antibiotic vancomycin. With the increase of staphylococcal resistance to methicillin, vancomycin is often a treatment of choice in infections with...
- Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
- Staphylococcal enteritis
Staphylococcal enteritis is a form of enteritis due to food poisoning caused by one of a variety of Staphylococcus bacteria. The illness is not necessarily the result of active infection, but can be the result of toxins that may have been left in the food due to improper handling prior to its...
External links