In our discussion of urinary tract infections, we turn to cystitis.
To define it we'd call it a clinical syndrome characterized by dysuria,
frequency, urgency, and occasionally suprapubic tenderness
caused by inflammation and infection of the bladder.
It's a disease that's much more common in women than men.
In fact, women have an incidence of asymptomatic bacteriuria
of around 1 to 3%.
Up to 60% of women
have had at least one episode of cystitis during their lifetime.
And 10% have it once a year.
The peak incidence
is among young, sexually active women, 18-24 years of age
and 2-5% have recurrent problems with cystitis.
Men, on the other hand, have a very low prevalence of cystitis
-- less than 0.1 %.
And when a man has cystitis,
we have to look for a complication
because there's usually some kind of obstructive uropathy
duplicating collecting system, some kind anatomical explanation
for cystitis
and we have to work them up
for urologic abnormalities.
The lack of circumcision
predisposes some men to cystitis
and among men who have sex with men
anal insertive sexual intercourse is a predisposing factor.
95% of the time,
the cause is a single species of bacterium,
so polymicrobial infections are unusual.
The most common bug is, as you might expect, Escherichia coli.
Now, we have lots of E. coli in our intestine -- lots of them.
But only about 20% of this E. coli are what we would call
uropathogenic E. coli.
So these E. coli are different.
They possess virulence factors
that the other E. coli do not have
that allow them to colonize and invade the urinary tract.
Most of them have what we call Type 1 fimbriae --
this fringe that surrounds the surface.
And this group of fimbria can attach to mannose residues which we find
commonly on the glycoproteins on urothelium.
And so they can attach to urothelium
and they're not washed away in the urinary stream.
These are called mannose-sensitive E. coli,
and the other E. coli's don't have them.
Furthermore, the normal urinary tract has a defense mechanism.
There is a glycoprotein present in trace amounts in urine.
It's called uromodulin.
The old name is Tamm-Horsfall protein,
and this uromodulin has mannose residues on it.
So these mannose-sensitive E. coli
will bind to the uromodulin
and then be washed away in the urine stream.
So they never get a chance to attach
because of the uromodulin that's present normally in urine.
Now recurrent and complicated cystitis
leads to an increased incidence of more resistant organisms,
that we don't usually find causing cystitis.
That would be, for example, Proteus, Pseudomonas aeruginosa,
Klebsiella pneumoniae, Enterobacter species,
and even some resistant E. coli,
and among the Gram-positives -- Enterococcus.