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Printable Handouts
Navigable Slide Index
- Introduction
- Important streptococcal species
- S. agalactiae - neonatal sepsis and meningitis
- S. pneumoniae
- S. pneumoniae - a candy coated bacterium
- S. pyogenes - the chain that links throat to heart
- S. pyogenes infections
- Serious life threatening complications
- Rheumatic fever - link to the heart
- APSGN (1)
- APSGN (2)
- Invasive S. pyogenes disease
- Child-bed sepsis (puerperal sepsis)
- Others conditions associated with S. pyogenes
- Psoriasis and obsessive compulsive behavior
- Microbiology of S. pyogenes
- Identification of group A Streptococcus
- S. pyogenes is resistant to innate immunity
- S. pyogenes interaction with host cell
- S. pyogenes surface is determinant of virulence
- Masters of immune avoidance
- Molecular mimicry - hyaluronic acid
- Binding of HA to CD44
- Key complement components
- Destruction of host chemotactic signals
- C5a peptidase (1)
- C5a peptidase (2)
- The M protein (1)
- The M protein (2)
- Tonsils are reservoir for recurrent infection
- S. pyogenes enter tonsils through M cells
- Streptococcal adhesins and invasins
- Multiple pathways of invasion
- M1-Fn and Sfb1-Fn invasion signals
- S. pyogenes infection and TGF-beta (1)
- S. pyogenes infection and TGF-beta (2)
- Superantigens
- Superantigens are nonspecific activators of T cells
- Summary
Topics Covered
- Important Streptococcal species
- S. pyogenes: the chain that links the throat to the heart
- Life threatening complications
- Rheumatic fever
- Acute post streptococcal glomerulonephritis
- Invasive S. pyogenes disease
- Strep throat activates psoriasis and obsessive compulsive behavior
- Identification of group A streptococcus
- S. pyogenes expresses a complex array of factors that interact with host defenses
- Molecular mimicry hides bacterium from host's defenses
- Key complement components
- Destruction of host chemotactic signals is critical for initiation of infection
- C5a peptidase
- M protein
- Tonsils are reservoir for recurrent infection
- Superantigens
Links
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Talk Citation
Cleary, P.P. (2009, October 29). Streptococcus pyogenes disease and molecular pathogenesis [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved December 6, 2024, from https://doi.org/10.69645/TPTC1388.Export Citation (RIS)
Publication History
Financial Disclosures
- Prof. P. Patrick Cleary, Lecturer, shared royalty payments from sales of lecture series.
A selection of talks on Clinical Practice
Transcript
Please wait while the transcript is being prepared...
0:00
Welcome to another lecture in
the series on bacterial
pathogenesis.
I'm Patrick Cleary.
I'm a Professor of
Microbiology at
the University of
Minnesota Medical School.
The focus of my lecture is
Streptococcus pyogenes,
a review of the diseases and
the molecular pathogenesis
associated with this organism.
0:25
I'd like to start
out by giving you
a brief overview of the
genus Streptococcus.
In the 1940s and 50s,
Rebecca Lancefield sub-classified
streptococci using
polysaccharide antigens produced
by different strains of
streptococci as the antigenic
marker of different species.
She grouped streptococci
into groups.
Group A through N.
Since her work, however,
microbiologists have given
these streptococci genus
and species names.
For example,
streptococcus pyogenes
is also called group
A streptococcus.
Many of these streptococci
have two names.
They have a genus
and species name,
but they also are referred
to by their group name.
Streptococcus agalactiae or
group B streptococcus is
the cause of neonatal infections
and I'll talk about
them in a little
more detail in the next slide.
Streptococcus dysgalactiae
is a complicated collection
of different strains
of streptococci.
Human isolates have been
termed group C and
G streptococcus
and resemble
Streptococcus pyogenes
both as far as the kinds
of infections they cause
and the virulence factors
that they produce.
Their classification
is a little bit murky,
so I prefer to continue to use
the Lancefield designation of
group C and G streptococci.
The dysgalactiae species
or group also contain
animal pathogens, Streptococcus
equi is an example.
It causes sore throats
or strangles in horses.
The oral streptococci are also
a complicated collection
of species and subspecies.
One which has been studied in
some detail is
Streptococcus mutans.
It's the cause of dental caries.
Other species in the oral cavity
which seldom cause
infections, however,
can cause serious infections
if they get into
the bloodstream.
The streptococcus most
often associated with
invasive and serious infections
is Streptococcus pneumoniae.
Once again, this is a
member of the normal flora
and many of us carry this
organism in our mouth.
I'll say a little more about
this organism in
an upcoming slide.