Editing Staphylococcus aureus (section)

== Microbiology ==
[[Image:Staphylococcus aureus Gram.jpg|thumb|250px|Gram stain of ''[[S. saprophyticus]]'' cells, which typically occur in clusters: The cell wall readily absorbs the [[crystal violet]] stain.]]
[[File:Staphylococcus aureus biochemical tests for identification.jpg|alt=|thumb|250x250px|Key characteristics of ''Staphylococcus aureus'']]
''Staphylococcus aureus'' ({{IPAc-en|ˌ|s|t|æ|f|ᵻ|l|ə|ˈ|k|ɒ|k|ə|s|_|ˈ|ɔːr|i|ə|s|,_|-|l|oʊ|-}},{{refn|{{Dictionary.com|Staphylococcus}} {{Dictionary.com|aureus}}}}{{refn|{{cite web |url=https://www.oxforddictionaries.com/definition/english/staphylococcus |archive-url=https://web.archive.org/web/20120818053533/http://oxforddictionaries.com/definition/english/staphylococcus |url-status=dead |archive-date=18 August 2012 |title=staphylococcus – definition of staphylococcus in English from the Oxford dictionary |publisher=[[OxfordDictionaries.com]] |access-date=20 January 2016 }} {{cite web |url=https://www.oxforddictionaries.com/definition/english/aureus |archive-url=https://web.archive.org/web/20120716032155/http://oxforddictionaries.com/definition/english/aureus |url-status=dead |archive-date=16 July 2012 |title=aureus – definition of aureus in English from the Oxford dictionary |publisher=[[OxfordDictionaries.com]] |access-date=20 January 2016 }}}} [[Greek language|Greek]] {{Lang|grc|σταφυλόκοκκος}} {{Gloss|grape-cluster berry}}, [[Latin]] {{Lang|la|aureus}}, {{Gloss|golden}}) is a [[Facultative aerobic organism|facultative anaerobic]], Gram-positive [[coccus|coccal]] (round) bacterium also known as "golden staph" and "oro staphira". ''S. aureus'' is nonmotile and does not form [[bacterial spore|spores]].<ref>"Pathogen Safety Data Sheet – Infectious Substances." Staphylococcus cells have a diameter of 0.7–1.2 um. Staphylococcus Aureus. Public Health Agency of Canada, 2011. Web</ref> In medical literature, the bacterium is often referred to as ''S. aureus'', ''Staph aureus'' or ''Staph a.''.<ref>{{cite web|url=https://www.ccohs.ca/oshanswers/biol_hazards/methicillin.html|title= Canadian Centre for Occupational Health and Safety |access-date=8 April 2016}}</ref> ''S. aureus''  appears as staphylococci (grape-like clusters) when viewed through a microscope, and has large, round, golden-yellow colonies, often with [[Hemolysis (microbiology)|hemolysis]], when grown on [[Agar plate#Blood agar|blood agar plate]]s.<ref name=Sherris>{{cite book | veditors = Ryan KJ, Ray CG | title = Sherris Medical Microbiology | edition = 4th | publisher = McGraw Hill | year = 2004 | isbn= 978-0-8385-8529-0 }}</ref> ''S. aureus'' [[asexual reproduction|reproduces asexually]] by [[binary fission]].  Complete separation of the [[cell division|daughter cells]] is mediated by ''S. aureus'' [[autolysin]], and in its absence or targeted inhibition, the daughter cells remain attached to one another and appear as clusters.<ref>{{cite journal | vauthors = Varrone JJ, de Mesy Bentley KL, Bello-Irizarry SN, Nishitani K, Mack S, Hunter JG, Kates SL, Daiss JL, Schwarz EM | title = Passive immunization with anti-glucosaminidase monoclonal antibodies protects mice from implant-associated osteomyelitis by mediating opsonophagocytosis of ''Staphylococcus aureus'' megaclusters | journal = Journal of Orthopaedic Research | volume = 32 | issue = 10 | pages = 1389–96 | date = October 2014 | pmid = 24992290 | pmc = 4234088 | doi = 10.1002/jor.22672 }}</ref>

''Staphylococcus aureus'' is [[Catalase#Catalase test|catalase-positive]] (meaning it can produce the enzyme catalase). Catalase converts [[hydrogen peroxide]] ({{chem|H|2|O|2}}) to water and oxygen. Catalase-activity tests are sometimes used to distinguish staphylococci from [[Enterococcus|enterococci]] and [[Streptococcus|streptococci]].  Previously, ''S. aureus'' was differentiated from other staphylococci by the [[coagulase|coagulase test]]. However, not all ''S. aureus'' strains are coagulase-positive<ref name=Sherris /><ref>PreTest, Surgery, 12th ed., p.88</ref> and incorrect species identification can impact effective treatment and control measures.<ref name="CNSA">{{cite journal | vauthors = Matthews KR, Roberson J, Gillespie BE, Luther DA, Oliver SP | title = Identification and Differentiation of Coagulase-Negative ''Staphylococcus aureus'' by Polymerase Chain Reaction | journal = Journal of Food Protection | volume = 60 | issue = 6 | pages = 686–8 | date = June 1997 | pmid = 31195568 | doi = 10.4315/0362-028X-60.6.686 | doi-access = free }}</ref>

[[Transformation (genetics)|Natural genetic transformation]] is a reproductive process involving DNA transfer from one bacterium to another through the intervening medium, and the integration of the donor sequence into the recipient genome by [[homologous recombination]].  ''S. aureus'' was found to be capable of natural genetic transformation, but only at low frequency under the experimental conditions employed.<ref name="pmid23133387">{{cite journal | vauthors = Morikawa K, Takemura AJ, Inose Y, Tsai M, Nguyen TL, Ohta T, Msadek T | title = Expression of a cryptic secondary sigma factor gene unveils natural competence for DNA transformation in ''Staphylococcus aureus'' | journal = PLOS Pathogens | volume = 8 | issue = 11 | pages = e1003003 | year = 2012 | pmid = 23133387 | pmc = 3486894 | doi = 10.1371/journal.ppat.1003003 | doi-access = free }}</ref> Further studies suggested that the development of competence for natural genetic transformation may be substantially higher under appropriate conditions, yet to be discovered.<ref name="pmid25155269">{{cite journal | vauthors = Fagerlund A, Granum PE, Håvarstein LS | title = ''Staphylococcus aureus'' competence genes: mapping of the SigH, ComK1 and ComK2 regulons by transcriptome sequencing | journal = Molecular Microbiology | volume = 94 | issue = 3 | pages = 557–579 | date = November 2014 | pmid = 25155269 | doi = 10.1111/mmi.12767 | s2cid = 1568023 | doi-access = free }}</ref>