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Life Sciences => Physiology & Medicine => Topic started by: sbposeidon on 27/11/2006 13:17:10

Title: How and why do wounds become infected, and what is "pus" ?
Post by: sbposeidon on 27/11/2006 13:17:10
Why do wounds that get infected sometimes pus?
Title: Re: How and why do wounds become infected, and what is "pus" ?
Post by: neilep on 27/11/2006 15:22:05
Quote from: sbposeidon on 27/11/2006 13:17:10
Why do wounds that get infected sometimes pus?


WIKI HAS SOME INFO :


Pus
From Wikipedia, the free encyclopedia


Pus is a whitish-yellow or yellow substance produced during inflammatory responses of the body that can be found in regions of pyogenic bacterial infections. An accumulation of pus in an enclosed tissue space is known as an abscess. A visible collection of pus within or beneath the epidermis, on the other hand, is known as a pustule or pimple. Pus is produced from the dead and living white blood cells which travel into the intercellular spaces around the affected cells.

Pus consists of a thin, protein-rich fluid, known as liquor puris, and dead neutrophils, which are part of the body's innate immune response. Neutrophils are produced in the bone marrow and released into the blood. When the need to fight infection arises, they move to the site of infection by a process known as chemotaxis, usually triggered by cytokine release from macrophages that sense invading organisms. At the site of infection they engulf and kill bacteria. After it has killed a bacterium, the neutrophil dies. These dead cells are then phagocytosed by macrophages, which break them down further. Pus, therefore, is the creamy material composed of these dead neutrophils.

Neutrophils are the most abundant type of leukocyte in human blood, comprising anywhere between 40% to 75% of leukocytes.

When seen in a wound or dry skin, pus indicates the area is infected and should be cleaned with antiseptic.

Something that creates pus is called suppurative, pyogenic, or purulent. If it creates mucus as well as pus, it is called "Mucopurulent".

Despite normally being of a whitish-yellow hue, changes in the color of pus can be observed under certain circumstances. Blue pus is found in certain infections of Pseudomonas aeruginosa as a result of the pyocyanin bacterial pigment it produces; amoebic abscesses of the liver, meanwhile, produce brownish pus. Pus might have a reddish tint to it after mixing with blood. Pus also can have an odor.

Pus in milk

Most types of milk will contain a small amount of pus. This is completely normal and usually safe unless there is an unusually high amount.

A somatic cell count is carried out before the milk leaves the farm. A dairy farmer's raw milk collection cannot exceed a somatic cell count of 750,000 per ml at the farm gate. Some cows may have udder infections increasing the cell count but these will be diluted as it is added to the other milk. By the time it is bottled up and sold it should contain only around 750,000 per ml, most likely much less.

Pasteurization is used to lower bacterial levels and not to reduce the somatic cell count.
Title: Re: How and why do wounds become infected, and what is "pus" ?
Post by: Karen W. on 27/11/2006 16:23:16
MmmmmmmmmmmAppetizing!LOL
Title: Re: How and why do wounds become infected, and what is "pus" ?
Post by: iko on 27/11/2006 17:22:40
"Pus bonum et laudabile"

transl. from Latin: pus good and laudable

The accumulation of neutrophil polymorphs within the extracellular space is the diagnostic histological feature of acute inflammation.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fmedweb.bham.ac.uk%2Fhttp%2Fmod%2F3%2F1%2Fa%2Fslides%2Fpus.gif&hash=efbd45e94a42e7e16120e718c03c4fdf)

High-magnification of pus in the lumen of the appendix. Pus consists of living and degenerate neutrophil polymorphs together with liquefied tissue debris.
The neutrophil is the main cell to mediate the effects of acute inflammation. If tissue damage is slight, an adequate supply is derived from normal numbers circulating in blood. If tissue damage is extensive, stores of neutrophils, including some immature forms, are released from bone marrow to increase the absolute count of neutrophils in the blood. To maintain the supply of neutrophils, growth factors derived from the inflammatory process stimulate division of myeloid precursors in the bone marrow, thereby increasing the number of developing neutrophils.
The main cellular events in acute inflammation, all of which are caused by chemical mediators, are as follows:
The normally inactive endothelium has to be activated to allow adhesion of neutrophils.
Normally inactive neutrophils have to be activated to enhance their capacity for phagocytosis, bacterial killing, and generation of inflammatory mediators.
Neutropllils have to develop the ability to move actively, in a directional fashion, from vessels towards the area of tissue damage.

http://medweb.bham.ac.uk/http/mod/3/1/a/cellular.html



8 x PUS = OctoPUS

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.garycmartin.com%2Fimages%2Foctopus_look.jpg&hash=d23cae57e472e0365440b64413601982)
http://www.garycmartin.com/images/octopus_look.jpg

ikod
Title: Re: How and why do wounds become infected, and what is "pus" ?
Post by: chris on 04/12/2006 00:00:20
The skin is one of our best natural defences against invading micro-organisms. It has physical strength, like a suit of armour, it has border guards, in the form of antibodies, mast cells and macrophages, and it has a transport network, the blood vessels, which bring in reinforcements when trouble arises.

But if the skin is breached by an injury, a portal of entry is created for bacteria and viruses. These bugs are tiny - often only a fraction of the size of our own cells - and they slip into a wound with ease. Because the wound site is warm, moist, and rich in food and raw materials such as components from damaged or dying cells, bacteria can quickly beging to thrive. Indeed, under ideal conditions, human pathogens like E. coli and Staph aureus can double their numbers every 20-30 minutes.

The body responds to the invasion by releasing chemicals known as cytokines, which act as hormonal rallying signals designed to draw in the immune system. Some of the first cells to arrive are the PMNLs or poly-morphonuclear leucocytes, or neutrophils for short. These are phagocytes, meaning that they are adapted to engulf and consume offending material, including bacteria.

As these flock to the wound site they become activated and undergo a respiratory burst. This involves producing large amounts of toxic intermediates, such as oxygen radicals, which are intended to destroy the bacteria. In the event this also kills adjacent cells and the neutrophils themselves. The resulting shrapnel is diluted into a soup of dead cells, bacteria and connective tissue debris by fluid leaking out of nearby blood vessels. This is pus. It gradually breaks down or leaks away, or, if you pop a spot or lance a boil, it can energetically spurt out like the oranges in the Outspan adverts...Yum

Chris
Title: Re: How and why do wounds become infected, and what is "pus" ?
Post by: DrN on 21/12/2006 00:00:08
Been working on this lately - just to scare you even more - skin wounds can transfer bacteria from the skin into the blood stream, and if you're immunocompromised, can lead to septicaemia. plus about 60% of people carry MRSA on the skin - commonly in the nose - at least transiently, some carry it permanently, which of course can cause horrendous problems for treatment if you do happen to be unlucky enough to develop a blood infection. so, don't pick your nose and wipe it in your wounds if you're immunocompromised!  [:D]
Title: How and why do wounds become infected, and what is "pus" ?
Post by: iko on 14/01/2007 16:59:46
quote:
don't pick your nose and wipe it in your wounds if you're immunocompromised! 
fishtails

...A neat example of natural selection:
either you boost your immune defense or...
succumb for overwhelming stupidity!

iko
Title: How and why do wounds become infected, and what is "pus" ?
Post by: moonfire on 15/01/2007 01:05:32
oh, boy...LOL
Title: How and why do wounds become infected, and what is "pus" ?
Post by: FuzzyUK on 18/01/2007 22:45:21
"Why do wounds that get infected sometimes pus?"

I've heard that if you p**s on a wound it stops pus. Something to do with the ammonia sterilising bacteria. Is that true?

Stop laughing and taking the pus.
Title: How and why do wounds become infected, and what is "pus" ?
Post by: DrN on 19/01/2007 23:23:15
if that were true, biotech companies would have gone out of business a long time ago. not to say it isn't true - will someone do a scientific controlled experiment and report back. sorry, no time to take this one on myself ... must delegate
Title: How and why do wounds become infected, and what is "pus" ?
Post by: chris on 19/01/2007 23:33:00
There may be a grain of truth in this because urine is (usually) sterile, especially if produced by a man (sorry ladies), moreso if he's circumcised (because the foreskin harbours bacteria).

Peeing on a wound can help to cleanse it because the sterile stream of liquid flushes out foreign bodies (dirt particles introduced by the injury) and bacteria. This reduces the risk of infection.

Chris
Title: How and why do wounds become infected, and what is "pus" ?
Post by: iko on 20/01/2007 00:28:00
It seems to be a widely discussed matter!
Why?

...I was told in Navy survival training to urinate on a wound to
help clean it, if nothing else was available (as when, for
example, one was shot down behind enemy lines in the middle of
nowhere).  Sounds gross, but remember that urine is actually
sterile: the liquid is composed of waste products from
your body that have been processed and neutralized.  It may
smell a bit (but not always), and be an odd color (again, not
always), but it's (a) sterile and (b) of your own body, so it's
neutral as far as you're concerned.  It's effectively a mild
saline solution as I understand it.
- Bill Y

from:   http://www.amusingfacts.com/cgi-bin/surf/surf_pass.cgi?template=st.html&cfile=may2301.html
Title: How and why do wounds become infected, and what is "pus" ?
Post by: DrN on 23/01/2007 19:40:42
so why is urine considered, in some circles, to be better than any other sterile liquid? I'd rather get a bottle of sterile water from the chemist than ask someone to pee on my wound!
Title: How and why do wounds become infected, and what is "pus" ?
Post by: iko on 24/01/2007 22:05:57
It is rather obvious that this should be an extreme
option when nothing else is available to flush and...
...clean a dirty wound.

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fmrmalph.wordpress.com%2Ffiles%2F2006%2F07%2Fneil-peeing.jpg&hash=1883338af3942d119c6fbb1b222242aa)
http://mrmalph.wordpress.com/files/2006/07/neil-peeing.jpg
ikod