Editing Infective endocarditis (section)

==Classification==
Infective endocarditis is divided into the three categories of acute, subacute, and chronic based on the duration of symptoms.<ref name="Hubers2020">{{cite journal |vauthors=Hubers SA, DeSimone DC, Gersh BJ, Anavekar NS |date=May 2020 |title=Infective Endocarditis: A Contemporary Review |url=https://doi.org/10.1016/j.mayocp.2019.12.008 |journal=Mayo Clinic Proceedings |volume=95 |issue=5 |pages=982–997 |doi=10.1016/j.mayocp.2019.12.008 |pmid=32299668 |url-access=subscription}}</ref> Acute infective endocarditis refers to the presence of signs and symptoms of infective endocarditis that are present for days up to six weeks.<ref name="Hubers2020"/> If these signs and symptoms persist for more than six weeks but less than three months, this is subacute infective endocarditis.<ref name="Hubers2020"/> Chronic infective endocarditis refers to the presence of such signs and symptoms when they persist for more than three months.<ref name="Hubers2020"/>
* ''[[Subacute bacterial endocarditis]]'' (SBE) is often due to [[streptococci]] of low virulence (mainly [[viridans streptococci]]) and mild to moderate illness which progresses slowly over weeks and months (>2 weeks) and has low propensity to hematogenously seed extracardiac sites.
* ''Acute bacterial endocarditis'' (ABE) is a [[fulminant]] illness over days to weeks (<2 weeks), and is more likely due to ''[[Staphylococcus aureus]]'', which has much greater virulence or disease-producing capacity and frequently causes metastatic infection.<ref name=Robbins/>

This classification is now discouraged, because the ascribed associations (in terms of organism and prognosis) were not strong enough to be relied upon clinically. The terms ''short incubation'' (meaning less than about six weeks) and ''long incubation'' (greater than about six weeks) are preferred.<ref>{{cite journal | vauthors = Morris AM | s2cid = 10450799 | title = How best to deal with endocarditis | journal = Current Infectious Disease Reports | volume = 8 | issue = 1 | pages = 14–22 | date = January 2006 | pmid = 16448596 | doi = 10.1007/s11908-006-0030-8 }}</ref>

=== Culture results ===
Infective endocarditis may also be classified as ''culture-positive'' or ''culture-negative''. By far the most common cause of "culture-negative" endocarditis is prior administration of antibiotics and can occur in up to 31% of cases.<ref>{{cite web |url=https://www.lecturio.com/concepts/endocarditis/| title=Endocarditis|website=The Lecturio Medical Concept Library |access-date= 18 July 2021}}</ref><ref name="auto"/>

Sometimes [[microorganism]]s can take a longer period of time to grow in the culture media, for example Cutibacterium spp.<ref name = "Sohail_2009">{{cite journal | vauthors = Sohail MR, Gray AL, Baddour LM, Tleyjeh IM, Virk A | title = Infective endocarditis due to Propionibacterium species | journal = Clinical Microbiology and Infection | volume = 15 | issue = 4 | pages = 387–94 | date = April 2009 | pmid = 19260876 | doi = 10.1111/j.1469-0691.2009.02703.x | doi-access = free }}</ref> and the HACEK bacteria group. Some organisms are said to be ''[[Growth medium|fastidious]]'' because they have demanding growth requirements. Some examples include pathogens like ''[[Aspergillus]]'' species, ''[[Brucella]]'' species, ''[[Coxiella burnetii]]'', ''[[Chlamydia (bacterium)|Chlamydia]]'' species. Due to delay in growth and identification in these cases, patients may be erroneously classified as "culture-negative" endocarditis.<ref>{{cite journal |vauthors= Holland T, Baddour L, Bayer A, Hoen B, Miro J, Fowler V |date= 1 September 2016 |title=Infective endocarditis|journal= Nature Reviews Disease Primers|volume= 2|issue= |pages=16059 |doi= 10.1038/nrdp.2016.59|pmid= 27582414|pmc= 5240923}}</ref>

=== Heart side ===
Endocarditis can also be classified by the side of the heart affected:
* People who [[intravenous]]ly inject [[opioid]]s such as [[heroin]] or [[methamphetamine]] may introduce infection which can travel to the right side of the heart, classically affecting the [[tricuspid valve]], and most often caused by ''S. aureus''.<ref name=Robbins/>
* Regardless of cause, left-sided endocarditis is the most common, while right-sided endocarditis accounts for 5-10% of cases and is more common in people who inject [[drug injection|IV drug]]s and in patients with congenital heart disease.<ref name=Robbins/><ref name="auto"/>

=== Infection setting ===
Another form of endocarditis is [[Iatrogenesis|healthcare-associated]] endocarditis when the infecting organism is believed to be transmitted in a health care setting like hospital, dialysis unit or a residential nursing home. [[Nosocomial]] endocarditis is a form of healthcare associated endocarditis in which the infective organism is acquired during a stay in a hospital and it is usually secondary to presence of intravenous catheters, [[total parenteral nutrition]] lines, [[pacemakers]], etc.<ref name=Harrison>{{cite book | vauthors = Kasper DL, Brunwald E, [[Anthony Fauci|Fauci AS]], Hauser S, Longo DL, Jameson JL| title = Harrison's Principles of Internal Medicine | publisher = McGraw-Hill |date=2005 | pages = 731–40  | isbn = 978-0-07-139140-5 | oclc = 54501403| title-link = Harrison's Principles of Internal Medicine }}</ref>

=== Valve type ===
Finally, the distinction between ''native-valve endocarditis'' and ''prosthetic-valve endocarditis'' is clinically important. Prosthetic valve endocarditis can be early (within 1 year of surgery) or late (> 1 year following valvular surgery).<ref name="auto"/>
* Early prosthetic valve endocarditis is usually due to intraoperative contamination or postoperative bacterial contamination which is usually [[nosocomial]] in nature.
* Late prosthetic valve endocarditis is usually due to community-acquired microorganisms.<ref name=Harrison/>

Prosthetic valve endocarditis is commonly caused by ''[[Staphylococcus epidermidis]]'' as it is capable of growing as a [[biofilm]] on plastic surfaces.<ref>{{cite journal | vauthors = Otto M | title = Staphylococcus epidermidis--the 'accidental' pathogen | journal = Nature Reviews. Microbiology | volume = 7 | issue = 8 | pages = 555–67 | date = August 2009 | pmid = 19609257 | pmc = 2807625 | doi = 10.1038/nrmicro2182 }}</ref> ''Cutibacterium acnes''  almost exclusively causes endocarditis on prosthetic heart valves.<ref name = "Sohail_2009" />