00:00
In our discussion of urinary tract infections, we turn to cystitis.
00:06
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.
00:21
It's a disease that's much more common in women than men.
00:25
In fact, women have an incidence of asymptomatic bacteriuria
of around 1 to 3%.
00:35
Up to 60% of women
have had at least one episode of cystitis during their lifetime.
00:43
And 10% have it once a year.
00:46
The peak incidence
is among young, sexually active women, 18-24 years of age
and 2-5% have recurrent problems with cystitis.
01:00
Men, on the other hand, have a very low prevalence of cystitis
-- less than 0.1 %.
01:09
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.
01:30
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.
01:47
95% of the time,
the cause is a single species of bacterium,
so polymicrobial infections are unusual.
01:56
The most common bug is, as you might expect, Escherichia coli.
02:02
Now, we have lots of E. coli in our intestine -- lots of them.
02:07
But only about 20% of this E. coli are what we would call
uropathogenic E. coli.
02:16
So these E. coli are different.
02:19
They possess virulence factors
that the other E. coli do not have
that allow them to colonize and invade the urinary tract.
02:28
Most of them have what we call Type 1 fimbriae --
this fringe that surrounds the surface.
02:34
And this group of fimbria can attach to mannose residues which we find
commonly on the glycoproteins on urothelium.
02:44
And so they can attach to urothelium
and they're not washed away in the urinary stream.
02:51
These are called mannose-sensitive E. coli,
and the other E. coli's don't have them.
03:00
Furthermore, the normal urinary tract has a defense mechanism.
03:07
There is a glycoprotein present in trace amounts in urine.
03:12
It's called uromodulin.
03:14
The old name is Tamm-Horsfall protein,
and this uromodulin has mannose residues on it.
03:23
So these mannose-sensitive E. coli
will bind to the uromodulin
and then be washed away in the urine stream.
03:33
So they never get a chance to attach
because of the uromodulin that's present normally in urine.
03:42
Now recurrent and complicated cystitis
leads to an increased incidence of more resistant organisms,
that we don't usually find causing cystitis.
03:55
That would be, for example, Proteus, Pseudomonas aeruginosa,
Klebsiella pneumoniae, Enterobacter species,
and even some resistant E. coli,
and among the Gram-positives -- Enterococcus.