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Hi, everyone. My name
is Dr. Sarah Fouch.
Within this session, we will
be considering E. coli.
We will be considering
the clinical conditions
associated with
this organism and
also the virulence
factors that are
produced to make this
a successful pathogen.
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E. coli is the most
common species of
organisms that fit within
the Escherichia family.
If we think about E. coli and we
think about the disease
spectrum it can cause,
it can range between
simple, uncomplicated
urinary tract infections
right the way through to
septicaemia and meningitis.
You can see that this is
a wide spectrum of
disease, and obviously,
this organism is going to need
different virulence
factors in order
to be able to cause that
spectrum of disease.
When we think about patients
suffering from septicaemia,
we normally find that there was
a primary focus
of the infection,
and very often this is
a urinary tract infection
or a gastrointestinal infection.
The patient has either
not sought treatment
or has had inadequate
treatment and
this infection has
then progressed into
the circulatory system and has
given the patient quite
a nasty septicaemia.
Let's think about E. coli.
As I said, a wide range
of disease spectrum.
When we think about
urinary tract infections,
E. coli is the leading cause of
urinary tract infections,
and up to 80% of
urinary tract infections are
caused by this organism.
If we think about the
patient demographic
that's most at risk of having
a urinary tract infection,
this is female patients.
E. coli originates from
the gastrointestinal tract,
our colon in particular.
When we think about
women's anatomy,
we can think why
women are more prone
to contaminating
themselves after
they've been to the toilet.
If they have
contaminated themselves,
they are at an increased risk of
urinary tract infections
associated with E. coli.
If we think about the
other end of the spectrum,
the other end of the spectrum
is neonatal meningitis.
Luckily, we don't tend to
see this as often as we used to.
One of the key virulence factors
here is the K1 capsular antigen.
If we think about the
number of strains that
we isolate from patients
with bacterial meningitis,
75% of those strains contain
the K1 capsular antigen.
If we think about the
patient demographic here,
this is mostly in
newborn children
under the age of three months.
The K1 capsular antigen is
very much associated
with invasion.
It has cytotoxic factors,
so these can cause
damage to the cells.
Interestingly,
the K1 capsular antigen,
actually, studies have
suggested that there are
specific binding sites for
the K1 antigen within the brain.
The K1 antigen is showing
tissue trophism to brain cells.
When we think about E. coli,
