View source for Pus

{{Short description|Fluid produced by inflammatory infection}}
{{Other uses}}
{{pp-pc1}}
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| caption         = [[Human eye|Eye]] with [[conjunctivitis]] exuding pus
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| field           = [[Infectious disease (medical specialty)|Infectious disease]]
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'''Pus''' is an [[exudate]], typically white-yellow, yellow, or yellow-brown, formed at the site of [[inflammation]] during infections, regardless of cause.<ref>
{{cite web|url=http://dictionary.reference.com/browse/Pus|title=Pus|website=dictionary.reference.com|access-date=2008-08-18}}
</ref><ref>
{{cite web|url=http://www.medicalnewstoday.com/articles/249182.php|title=Pus – What Is Pus?|website=medicalnewstoday.com|access-date=2016-08-19}}
</ref> An accumulation of pus in an enclosed tissue space is known as an [[abscess]], whereas a visible collection of pus within or beneath the [[epidermis (skin)|epidermis]] is known as a [[pustule]], [[pimple]] or spot.

==Description==
Pus consists of a thin, [[protein]]-rich fluid (historically known as ''liquor puris''<ref>{{Cite book|url=https://books.google.com/books?id=KD1HAAAAYAAJ&q=%22liquor+puris%22|title=British Medical Journal|date=1917|publisher=British Medical Association|pages=751–754|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=6LA1AQAAMAAJ&q=%22liquor+puris%22&pg=PA251|title=Journal|last=Society|first=Louisiana State Medical|date=1846|pages=251|language=en}}</ref>) and dead [[leukocytes]] (white blood cells) from the body's [[immune response]] (mostly [[neutrophils]]).<ref name="Barer 2012 pp. 168–173">{{cite book | last=Barer | first=M.R. | title=Medical Microbiology | pages=168–173 | chapter=The natural history of infection | publisher=Elsevier | year=2012 | isbn=978-0-7020-4089-4 | doi=10.1016/b978-0-7020-4089-4.00029-9 }}</ref> During infection, [[T helper cells]] release [[cytokine]]s, which trigger neutrophils to seek the site of infection by [[chemotaxis]]. There, the neutrophils release [[Neutrophil granule|granules]], which destroy the bacteria. The bacteria resist the immune response by releasing [[toxins]] called [[leukocidin]]s.<ref name=Biology>Madigan, Michael T. and Martin, John M. Brock Biology of Microorganisms 11th ed. Pearson Prentice Hall. US. 2006: 734</ref> As the neutrophils die off from toxins and old age, they are [[phagocytosis|destroyed]] by macrophages, forming the viscous pus. Bacteria that cause pus are called pyogenic.<ref name="Biology" /><ref>{{DorlandsDict|seven/000088920|pyogenic}}</ref>

[[File:Pus with blood coming out of ring finger, photographed in India, July 10, 2024.jpg|thumb|Pus with blood coming out of ring finger]]
Although pus is normally of a whitish-yellow hue, changes in the color can be observed under certain circumstances. Pus is sometimes green because of the presence of [[myeloperoxidase]], an intensely green antibacterial protein produced by some types of white blood cells. Green, foul-smelling pus is found in certain infections of ''[[Pseudomonas aeruginosa]]''. The greenish color is a result of the bacterial pigment [[pyocyanin]] that it produces. [[Amoebic]] abscesses of the [[liver]] produce brownish pus, which is described as looking like "[[anchovy paste]]". Pus from anaerobic infections can more often have a foul odor.<ref name="Topazian 2002">{{cite book|vauthors=Topazian RG, Goldberg MH, Hupp JR |title=Oral and maxillofacial infections|year=2002|publisher=W.B. Saunders|location=Philadelphia|isbn=978-0721692715|edition=4}}</ref>

In almost all cases when there is a collection of pus in the body, a clinician will try to create an opening to drain it. This principle has been distilled into the famous [[Latin language|Latin]] [[aphorism]] "{{lang|la|[[Ubi pus, ibi evacua]]}}" ("Where there is pus, evacuate it").

Some disease processes caused by pyogenic infections are [[impetigo]],<ref name=Dermatopathology>{{citation|pages=83–85|chapter=Infections Caused by Common Pyogenic Bacteria|publisher=Springer |location=Berlin Heidelberg|doi=10.1007/3-540-30244-1_12|title=Dermatopathology|year=2006|isbn=978-3-540-30245-2|doi-access=free}}</ref> [[osteomyelitis]], [[septic arthritis]] and [[necrotizing fasciitis]].
[[File:Abszess.jpg|thumb|An [[abscess]] is an enclosed collection of pus.]]
[[File:Cholangitis.jpg|thumb|[[Duodenoscopy]] image of [[hepatopancreatic ampulla]] with pus exuding from it, indicative of [[cholangitis]]]]

==Pyogenic bacteria==
Many species of bacteria may be involved in the production of pus. The most commonly found include:<ref name=manual-of-surgery>{{cite web|url=http://www.manual-of-surgery.com/content/0013-Pyogenic-Bacteria.html|title=Pyogenic Bacteria|work=Manual of Surgery|publisher=Oxford Medical Publications|last1=Thompson|first1=Alexis|last2=Miles|first2=Alexander|edition=6th|year=1921|oclc=335390813}}</ref>
*''[[Staphylococcus aureus]]''
*''[[Staphylococcus epidermidis]]''
*''[[Streptococcus pyogenes]]''
*''[[Escherichia coli]]'' (Bacillus coli communis)
*''[[Streptococcus pneumoniae]]'' ([[Albert Fraenkel|Fraenkel's]] pneumococcus)
*''[[Klebsiella pneumoniae]]'' ([[Carl Friedländer|Friedländer's]] bacillus)
*''[[Salmonella typhi]]'' (Bacillus typhosus)
*''[[Pseudomonas aeruginosa]]''
<!-- *''[[Micrococcus tetragenus]]'' not sure of current name-->
<!-- *''[[Pneumo-bacteria]]'' Not sure of current name-->
*''[[Neisseria gonorrhoeae]]''
*''[[Actinomyces]]''
*''[[Burkholderia mallei]]'' (Glanders bacillus)
*''[[Mycobacterium tuberculosis]]'' (tubercle bacillus)

Staphylococcus aureus bacteria is the most common cause of [[boil]]s.

==Historical terminology==
{{anchor|historical}}
In the pre-[[asepsis]] era, surgeon [[Sir Frederick Treves, 1st Baronet|Frederick Treves]] (1853–1923) wrote,
"Practically all major wounds [[wiktionary:suppurate#Verb|suppurate]]d. Pus was the most common subject of converse [among surgeons], because it was the most prominent feature in the surgeon's work. It was classified according to degrees of vileness."{{px1}}{{r|nuland|page=347}}
But pus of the right kind was considered desirable.{{r|vanhoosen|page=80}}
"If a patient was lucky{{nbsp}}... a thick cream-colored odorless fluid would appear within five or six days";
such "laudable" pus was considered "a sure sign that the wound would heal"{{px1}}{{r|nuland|page=344}}
because it meant "Nature has put up a bold fight against the invader".{{r|scott}}
"On the other hand, if the pus gradually became watery, blood tinged and foul smelling, it was designated 'sanious'{{px1}}{{r|schneider}}
[or 'ill-conditioned'{{px1}}]{{px1}}{{r|williams}}
and the wound condition was considered unfavorable".{{r|schneider}}
It later came to be understood that "laudable" pus generally implied an invasion of relatively benign [[staphylococcus]], while "ill-conditioned" pus usually meant the more dangerous [[streptococcus]] was present.{{r|nuland|page1=345|schneider|page2=247}}

== See also ==
* [[Pyoderma]]
* [[Serous fluid]]
* [[Carbuncle]]
* [[Phlegmon]]
* [[Empyema]]

== References ==
{{Reflist
|refs =
{{refn |name=nuland |{{cite book |last=Nuland |first=Sherwin B. |title = Doctors: The Biography of Medicine |isbn=978-0-307-80789-2 |url = https://books.google.com/books?id=hVePdRGsX2sC |year=2011 |publisher=Knopf Doubleday }} {{closed access}} }}

{{refn |name=schneider |{{cite book |last=Schneider |first=Albert |title=Pharmaceutical bacteriology |page=[https://archive.org/details/cu31924000233829/page/n260 247] |edition=2nd |url = https://archive.org/details/cu31924000233829 |year=1920 |publisher=P. Blakiston}} }}

{{refn |name=williams |{{cite book |last=Williams |first=Charles J. B. |year=1848 |publisher=Churchill |title=Principles of Medicine: Comprising General Pathology and Therapeutics, and a Brief General View of Etiology, Nosology, Semeiology, Diagnosis, and Prognosis: With Additions and Notes by Meredith Clymer|url = https://books.google.com/books?id=mfcGAAAAcAAJ&pg=PA306 |page=306 }} {{open access}} }}

{{refn |name=vanhoosen |{{cite journal|last=Van Hoosen |first=Bertha |id=UOM:39015006945235 |title=A Woman's Medical Training in the Eighties |date=Autumn 1947 |pages=77{{ndash}}81 |url = https://books.google.com/books?id=qhNYAAAAMAAJ&pg=PA80 |publisher=University of Michigan Libraries |journal=Quarterly Review of the Michigan Alumnus: A Journal of University Perspectives }} {{open access}} }}

{{refn |name=scott |{{cite book |url = https://books.google.com/books?id=s5FIAQAAIAAJ&pg=PA603 |location=Chicago |publisher=Eger |title = An indexed system of veterinary treatment |year=1922 |page=603 |first=William |last=Scott }} {{open access}} }}
}}

== External links ==
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*{{Commonscatinline}}

[[Category:Body fluids]]
[[Category:Immune system]]
[[Category:Medical terminology]]
[[Category:Excretion]]