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Hello, everyone. My name
is Dr. Sarah Fouch.
Welcome to this short
recording where we
will be considering the
clinical conditions
associated with
Streptococcus pneumoniae
and the virulence factors
that this organism can
produce in order to make
it a successful pathogen.
0:22
This is a gram positive coccus
and it has an oval shape.
Streptococci require
quite complex
growth requirements
within their media and blood
is a really good example.
Streptococci can grow
nicely on blood agar.
The reason for this is because
streptococci are
catalase negative.
They need to utilise
the catalase from the
blood in order to
break down the toxic
hydrogen peroxide
into water and oxygen.
When we visualise streptococci
and Streptococcus
pneumoniae colonies,
they can either have capsulated
colonies or
non-capsulated colonies.
When they are capsulated,
they are usually large
and very mucoid.
Sometimes you can take the
lid off of an agar plate and
they are so mucoid, they
almost drip into the lid.
In comparison, the
non-capsulated forms
look very small and flat.
They almost have a
draughtsman piece appearance.
I'm talking about the
board game, draughts,
here where you have
the piece that has
a little dip in the middle, and
we'll discuss why
that's the case now.
