We continue our discussion,
now turning to the subject of urethritis.
We define urethritis
as inflammation of the urethra caused by
sexually transmitted pathogens.
This is to be distinguished from the organisms
that cause urinary tract infections.
One of the most infamous
of these organisms that cause urethritis
is Neisseria gonorrhoeae,
which has a fairly strikingly high incidence
in the United States of more than 700,000 cases per year.
The incidence in all of the countries of western Europe
is much lower than in the United States.
However, there are high and rising rates
of urethritis due to this organism in eastern Europe.
We find it most frequently among people 15-24 years of age.
We find it more in blacks than in whites.
And we find it more in men who have sex with men
more than heterosexual men.
The other infamous organism is Chlamydia trachomatis.
It is the major cause of non-gonoccal urethritis.
In the United States, as a matter of fact,
the incidence is twice that of gonorrhea.
But something is very important to remember
is that among men who are diagnosed with gonorrhea,
if that is the only agent treated
then about 20% of men will also come down
with non-gonoccal urethritis.
We'll talk later that you must treat for both empirically.
Neisseria gonorrhoeae
causes a grossly purulent type of discharge from the urethra,
and it is very painful upon urination.
If you were to Gram-stain this discharge,
you would find the classic Gram-negative,
intracellular diplococci.
On the other hand, non-gonoccal urethritis
is not so nearly so purulent.
It may even be a clear discharge,
and if one were to Gram-stain this discharge,
you would find no organisms.
You would find lots of white blood cells, as shown here.
The major causes of non-gonoccal urethritis
are Chlamydia trachomatis,
Ureaplasma urealyticum
and Mycoplasma genitalium.
Let's turn now to Nieisseria gonorrhoeae,
and talk about the incubation period.
It's actually pretty short,
approximately 48 hours after exposure
to someone with gonorrhea.
This organism will begin its dirty work.
The gonococci actually enters the urethral epithelial cells,
and kill many of them,
and then the organisms are released again.
Nieisseria gonorrhoeae has something called
lipooligosaccharide,
and this lipooligosaccharide causes the release
of very high concentrations of inflammatory cytokines
from the epithelial cells as they're dying.
These cytokines include
tumor necrosis factor alpha
IL-6, IL-1-beta, and IL-8.
And all of these causes
not only the urethral cells to be shed into the lumen,
but numerous white blood cells.
And so that's why in gonorrhea
the discharge is grossly purulent, full of white cells.
The incubation period for Chlamydia trachomatis,
on the other hand, is much longer.
From 7 to 14 days after exposure.
The infectious agent is this tiny little microorganism,
in the form of elementary bodies.
This is the infectious form.
The urethral cells are infected by these elementary bodies,
as shown in this cartoon,
and made into inclusions.
These inclusions fuse and become reticulate bodies,
And it's the reticulate bodies that divide and enlarge,
and produce more of these infectious particles
known as elementary bodies,
which can then transmit the infection to others.
So as I mentioned, the incubation period is 7-14 days.
And the natural history of untreated infection is
we don't know an awful lot about it.
What we do know is that these organisms may persist
in the urethra of men for up to 6 months.
The discharge produced is not nearly so purulent.
It's whitish, gray, and sometimes even clear,
and sometimes it's even minimal.