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we turn our attention now to what some
people call the granddaddy of them all
among sexually transmitted infections
and that is syphilis syphilis is a
chronic multistage sexually transmitted
infection caused by a spirochete known
as Treponema pallidum and i think you
can see from the attached picture that
this microorganism is spiral in shape
syphilis has not gone away indeed there
are 11 million new cases globally every
year the highest incidence in the United
States is among men who have sex with
men especially among poor minority
communities in the southern United
States in Europe the rates are between
4.4 and 10.4 per hundred thousand
population with especially increased
rates in Eastern Europe and Russia the
epidemiology of syphilis has been
greatly influenced by the HIV pandemic
there are very high rates of HIV
infection among people who are diagnosed
with syphilis syphilis affects a million
and a half pregnant women each year and
about five
percent of those women are going to have
some untoward outcome from infection in
the form of miscarriage stillbirth
neonatal death a very low weight birth
weight infant or an infant born with
congenital syphilis let's talk something
about this organism the organism is
known as Treponema pallidum subspecies
pallidum and it's a spirochete and note
how thin this organism is it's 0.2
microns in diameter
a typical bacterium is going to be at
least one micron in diameter and usually
several microns wide because it's so
thin you cannot visualize visualize this
organism by conventional microscopy it's
so thin it's transmitted by sexual
contact and it's got these flagella
inside of the periplasmic space of the
organism that extend from these little
column motors they're really bio motors
at each pole that overlap in the middle
and it causes the organism to move by
wiggling this is an undulating movement
and it goes through fluids tissue and
because it's so thin it goes between
cells so as I mentioned it is spread by
person-to-person transmission usually by
intimate contact either genital genital
contact or oral genital contact and this
organism can directly penetrate the
mucous membranes by little minut breaks
or abrasions in the skin or the mucosa
once it does that it can disseminate
through the lymphatics gets into the
bloodstream and circulates everywhere
once it gets into the bloodstream these
trepan imbibed to the vascular
endothelium they cause in a sense of
vasculitis and that can happen in their
target organs and involve the
parenchymal of those organs and these
thin spirochetes can penetrate through
tight junctions separating endothelial
cells Treponema pallidum has an outer
membrane which helps protect it from
recognition by our immune system however
ultimately is going to be phagocytosis
by dendritic cells and then these cells
will present the Treponema antigens to
b-cells and t-cells
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