As you've mentioned, the presence of a green discharge is often
indicative of a bacterial infection, although distinguishing between
bacterial and viral infections cannot be done by color alone.
Chlamydia and pseudomonas (and many other bacteria) can produce a
clear, whitish or yellowish exudate:
"Men with chlamydia may also have no symptoms. The main symptoms they
may have are burning on urination or a small amount of clear discharge
from the penis. This is most obvious in the morning before urination."
University of Montana Curry Health Center: Chlamydia Infections
http://www.umt.edu/CHC/healthlibrary/hlchlamydia.htm
"Pseudomonal infections, by and large, involve the respiratory system.
Signs of the infection may include clear or yellowish discharge from
one or both nostrils, sneezing, scratching at the nose and ears, and
conjuctivitis (red eyes)."
HotSpot for Birds: Pseudomonas Infection in Pet and Breeding Birds
http://www.multiscope.com/hotspot/pseudomonas.htm
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The substance that give pus its green color is an enzyme called
myeloperoxidase (MPO). You were on the right track when you said
"would it be produced by one of the body's defenses specific to
bacteria, such as neutrophils..."
Below you'll find material on this interesting subject.
"This neutrophil influx should be associated with a change in
secretions from mucoid to purulent (because the myeloperoxidase from
the neutrophils is green)..."
Cache of Medscape: Relationship of Sputum Color to Nature and
Outpatient Management of Acute Exacerbations of COPD
http://216.239.41.104/search?q=cache:M0egUqYgy0cJ:www.medscape.com/viewarticle/405951
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"Myeloperoxidase was first isolated by Agner in 1941, who gave it the
name 'verdoperoxidase', because of its green colour and ability to
catalyse peroxidase reactions. It is MPO that gives pus its greenish
tone."
Cache of Organtec: Anti-Lysocyme
http://216.239.41.104/search?q=cache:Fc9ag_tnI94J:www.orgentec.com/english/instruction/526ex.html
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"Neutrophil granules contain antimicrobial or cytotoxic substances,
neutral proteinases, acid hydrolases and a pool of cytoplasmic
membrane receptors. Among azurophil granule constituents
myeloperoxidase (MPO) is a critical enzyme in the conversion of
hydrogen peroxide to hypochlorous acid. Together with hydrogen
peroxide and a halide cofactor it forms the most effective
microbicidal and cytotoxic mechanism of leukocytes - the
myeloperoxidase system. MPO is responsible for the characteristic
green color of pus."
Inflammation and Fever: Neutrophil Granules
http://nic.sav.sk/logos/books/scientific/node16.html
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"Myeloperoxidase (MPO) refers to a group of at least three
closely-related di-heterodimeric isoenzymes consisting of two light
chains (15,000 daltons each) and two heavy chains (55,000 to 60,000
daltons each) which are found in neutrophils and blood monocytes
(Figure 15A). MPO is not found in macrophages, which lose MPO within 2
days of entering the tissues. MPO is synthesized only during the
promyelocyte stage, prior to final granulocyte/ monocyte commitment.
MPO is an intensely green molecule due to the presence of two
heme-like chlorin prosthetic groups. It confers a green color to
neutrophils (yes, these 'white blood cells' are green!)."
Dr. Ken Miyasaki: Phagocytes-Neutrophils
http://www.dent.ucla.edu/pic/members/neutrophils/neutrophils2.html
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"The neutrophils can enhance the destructive power of hydrogen
peroxide by reacting it with the salt in our body using an enzyme
called myeloperoxidase. This enzyme is an amazing green colour in the
test tube but most people are familiar with it as the green phlegm in
their handkerchief during a bad head cold."
University of Canterbury: Reducing Free Radicals - A Dietary Revolution
http://www.zool.canterbury.ac.nz/freeradicals.htm
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"The process begins when a type of white blood cell called the
neutrophil (or phagocyte) senses microbial invasion, migrates to the
site, and adheres to and ingests the microbe, by sequestering it in an
intracellular sac called a phagosome. During this envelopment, the
phagocytes consume a large amount of oxygen in a 'respiratory burst.'
The oxygen is converted to hydrogen peroxide. Myeloperoxidase, a key
ingredient of the granules present in neutrophils, is released along
with an arsenal of other toxic agents into the phagosome containing
the ingested bacteria. The accumulation of neutrophils forms pus,
which gets its green color from myeloperoxidase."
University of Washington: Neutrophils Work to Combat Infection
http://depts.washington.edu/drrpt/2001/research/neutrophils.html
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Given the fact that pus is green because of myeloperoxidase, we might
well wonder: why is myeloperoxidase green?
"Recently, we have determined the structure of human myeloperoxidase,
an enzyme that catalyses the peroxidation of chloride ions to
hypochlorite in white blood cells. This reaction is important in the
anti-viral and anti-bacterial activities of these cells. We have found
that the unusual green color of this enzyme results from chemical
bonds between the heme and the protein and we are continuing to
explore the mechanism of catalysis of this powerful oxidising enzyme."
University of Miami School of Medicine: Roger Fenna
http://amiga1.med.miami.edu/Faculty/fenna.htm
"Green heme proteins are not unprecedented, and their color can arise
through several different mechanisms. 1) Myeloperoxidase contains a
conventional heme cofactor that is covalently attached to the protein
by two methoxy esters and a methionine-derived sulfonium linkage.
Coupled with a nonplanar bend in the heme, these linkages are believed
to be the origin of its green color."
JBC Online: A Ubiquitously Expressed Human Hexacoordinate Hemoglobin
http://www.jbc.org/cgi/content/full/277/22/19538#B38
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Google search strategy:
Google Web Search: "pus" + "green" + "mpo OR myeloperoxidase"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=pus+green+mpo+OR+myeloperoxidase
Google Web Search: "chlamydia" + "clear OR yellow" + "discharge"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=chlamydia+%22clear+OR+yellow%22+discharge
Google Web Search: "pseudomonas" + "clear OR yellow" + "discharge"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=pseudomonas+%22clear+OR+yellow%22+discharge
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I hope this information is useful. If anything is unclear, or if a
link does not function, please request clarification; I'll be glad to
offer further assistance before you rate my answer.
Best regards,
pinkfreud |
