bacterial toxins are present in the
blood. (See also bacteraemia.)
Septicaemia usually arises through es-
cape of bacteria from a focus of infection,
such as an abscess, and is more likely to
occur in people with an immunodefici-
ency disorder, cancer, or diabetes mellitus;
in those who take immunosuppressant
drugs; and in drug addicts who inject.
Symptoms include a fever, chills, rapid
breathing, headache, and clouding of
consciousness.The sufferer may go into
life-threatening septic shock.
Glucose and/or saline are given by
intravenous infusion, and antibiotics
by injection or infusion. Surgery may be
necessary to remove the original infec-
tion. If treatment is given before septic
shock develops, the outlook is good.
septic arthritis A type of arthritis
caused by a bacterial infection entering
a joint via an open wound. Symptoms
of septic arthritis appear suddenly and
may include swelling, tenderness, and
fever. If pus builds up, the joint may be
permanently damaged.
Fluid is taken from the joint and is
analysed to determine the presence of
infection (seeaspiration), and pus may
be drained to help relieve pain. Initially,
treatment is with intravenous antibiotic
drugs, followed by oral antibiotics for
several weeks or months after that.
septic shockA life-threatening condi-
tion in which there is tissue damage
and a dramatic drop in blood pressure
as a result of septicaemia.
septumA thin dividing wall within or
between parts of the body.
sequelaA condition that results from or
follows a disease, disorder, or injury. The
term is usually used in plural (sequelae)
to refer to the complications of a disease.
sequestrationA portion of diseased or
dead tissue separated from, or joined ab-
normallyto, surrounding healthy tissue.
serologyA branch of laboratory medicine
concerned with analysis of blood serum.
Applications of serological techniques
include the diagnosisof infectious dis-
eases by the identification of antibodies,
the development of antiserumprepara-
tions for passive immunization, and the
determination of blood groupsin pater-
nity testingand forensic investigations.
serotoninA substance found in many
tissues, particularly blood platelets, the
digestive tract lining, and the brain. Sero-
tonin is released from platelets at the
site of bleeding, where it constricts small
blood vessels, reducing blood loss. In
the digestive tract, it inhibits gastric
secretion and stimulates smooth mus-
cle of the intestine. In the brain, where
it acts as a neurotransmitter, levels are
reduced in people who are depressed;
certain antidepressantsraise the level.
Serotonin agonists are used to block its
effects in acute migraine attacks.
serotonin agonistsA group of drugs,
also known as 5HT 1 agonists, used to
treat acute attacks of migraine. They
work on the same receptors in the brain
as 5 hydroxytryptamine (5HT), a neuro-
transmitterand vasodilator. Common
serotonin agonists include naratriptan
and sumatriptan. These drugs can cause
chest pain, particularly in people with
heart disease. They should be used with
caution in those at increased risk of cor-
onary artery disease. Other side effects
include flushing, tingling, and nausea.
serotonin antagonistsA group of drugs
used to treat the nausea and vomiting
caused by radiotherapyand anticancer
drugs. They are also used to control
nausea and vomiting following surgery.
Common serotonin antagonists include
granisetron and ondansetron.
sertralineA selective serotonin reuptake
inhibitor drug used in the treatment of
depression (see antidepressants).
serumThe clear fluid that separates from
bloodwhen it clots. It contains salts, glu-
cose,and proteins, including antibodies.
Serum from the blood of a person who
has been infectedwith a microorganism
usually contains antibodies that can pro-
tect other people from that organism if
injected into them. Such a preparation
is called an antiserum; its use forms the
basis of passive immunization.
serum sicknessA type of hypersensi-
tivityreaction that may develop about
10 days after injection with an anti-
serumof animal origin or after taking
certain drugs such as penicillins. Symp-
toms may include an itchy rash, joint
pain, fever, and enlarged lymph nodes.
In severe cases, a state similar to shockSEPTIC ARTHRITIS SERUM SICKNESS
S