00:01
Hello and welcome back to
the Nephrology curriculum.
00:04
Today we're going to be talking about
urinary tract infection or UTI.
00:09
Let's start out
with a clinical case.
00:11
The 29 year old woman comes
to the clinic
complaining of a three-day history
of burning with urination
and increased in
urinary frequency.
00:19
She has suprapubic discomfort
but no new vaginal discharge.
00:23
She's in a monogamous
relationship with her husband
and she's been sexually active
with her last sexual
encounter three days ago.
00:29
Her last menstrual period was
about one week prior.
00:32
On exam, she's afebrile
her blood pressures 118/72.
00:37
Pulse is 70.
00:38
Her exam is relatively unremarkable
except for mild suprapubic
tenderness to palpation
but no costovertebral CVA tenderness
to palpation or percussion.
00:48
The remainder of the exam
is normal.
00:51
Her labs demonstrate
on urine analysis has
specific gravity of 1.02.
00:56
She's got trace blood
and leukocyte esterase positive
and nitrite positive as well.
01:02
So the question is,
what is the most likely cause
of this woman symptoms?
Let's go through
our case and see if we can find out.
01:09
So I think what's important in
looking at the history.
01:12
She's complaining of dysuria
that's burning with
urination frequency and urgency
along with suprapubic discomfort
very suggestive of cystitis.
01:21
She also had sexual intercourse,
which has been associated
with UTIs in women.
01:26
And on exam, she's got mild
suprapubic tenderness
without having actual CVA tenderness
suggestive of an isolated cystitis.
01:35
On urine analysis,
we can see that having
leukocyte esterase
indicates the presence of white cells.
01:42
In nitrates indicate the presence
of a gram negative
organisms such as E. coli.
01:48
So the question is,
what is the most likely cause
of this patient symptoms
an uncomplicated urinary tract infection
or to be more specific cystitis.
02:00
So,
what would be most appropriate
in terms of the next step
in management of this
particular patient.
02:05
Given her symptoms,
and given her urine analysis.
02:09
I think it's most appropriate
to start empiric therapy.
02:12
So we can use empiric
antibiotic therapy with nitrofurantoin
or trimethoprim
sulfamethoxazole.
02:18
So before we move on
I think it's important
to review some terminology
and definitions.
02:23
Let's start with cystitis.
02:25
Cystitis is infection of the
bladder or lower urinary tract.
02:30
Pyelonephritis is
infection of the kidney
or the upper urinary tract.
02:35
You'll also hear people talk about
uncomplicated
urinary tract infections.
02:39
This is infection
in the urinary tract
where there's no functional
or anatomical abnormality.
02:44
There's no functional impairment
or concomitant disease
that would promote the UTI.
02:49
A complicated UTI
on the other hand
is when infection is associated
with a structural
or functional abnormality
in the genitourinary tract.
02:57
Or the presence
of an underlying disease
that increases risk
of acquiring an infection.
03:03
You'll also hear the term
asymptomatic bacteriuria.
03:06
That means that
you have presence
of two separate consecutive
clean voided urine specimens
where there's 10 to the fifth or more
colony forming units per milliliter
of the same bacteria
in the absence of symptoms.
03:19
Okay, so let's move on,
when we think about
who's vulnerable to UTIs.
03:24
There's five different
demographic populations
that we really need to consider.
03:28
First,
urinary tract infection
in children.
03:32
Second women in
uncomplicated cystitis.
03:35
Third is women
with recurrent cystitis.
03:38
And then fourth complicated
urinary tract infections,
and then finally
asymptomatic bacteriuria.
03:45
So when we think
about the pathogenesis of UTI
in an uncomplicated infection,
uropathogens are present
in the rectal flora.
03:53
They can enter the bladder
by the urethra.
03:56
We do see an increase
in frequency in women
and that's because of
the smaller distance
between the anus
and the urethral meatus.
04:02
They're also hosts determinants
that are involved
in promoting an uncomplicated
infection.
04:07
Behavioral.
04:08
This includes sexual intercourse
recent antimicrobial use
or suboptimal voiding habits.
04:13
So of people incompletely void.
04:17
Their genetic
determinants as well,
the innate and adaptive immune
response is going to be important
increased epithelial adherents
of some of the bacteria
and a prior history of recurrent
cystitis will also play a role.
04:29
And finally, there
are biological determinants
the postmenopausal
state or glycosuria
particularly in diabetics.
04:38
How about an a
complicated infection.
04:40
In terms of pathogenesis
the same risk factors
and host determinants
from uncomplicated UTI
play a role here as well.
04:47
But in addition these patients
will often have a structural
or functional abnormality
of the genitourinary tract.
04:55
They can have obstruction
or stasis of urine outflow
or they might have
impaired host defense.
05:01
This might be a patient
whose immunosuppressed.
05:04
There's also an association
with diabetes mellitus.
05:08
People with diabetes or going to be
more prone to things like renal abscess.
05:12
Emphysematous pyelonephritis
and xanthogranulomatous
pyelonephritis,
which we'll be
talking about later.
05:19
So let's get back to our original
clinical case that we were talking about.
05:22
Remember 29 year old women
who came into the clinic
complaining of cystitis.
05:27
Her symptoms of dysuria
frequency and urgency
were very suggestive of cystitis.
05:32
She had the right
behavioral determinants.
05:34
She had recently had
intercourse with her husband.
05:37
And on physical exam,
she had signs of cystitis
by having suprapubic tenderness.
05:42
We knew without having
CVA tenderness and fever
that she likely did not have
pyelonephritis or infection of her kidney
and her urine certainly looked
as if there was
infection with cystitis.
05:53
She had leukocyte esterase
that was positive
as well as nitrates,
which were ended indicative
of gram negative organisms.
06:00
So our question is,
what microbial agent
would most likely be
the cause of her cystitis.
06:08
The answer is E. coli.
06:12
What if the patient though instead
was a 68 year old gentleman
who was hospitalized
with a urinary catheter?
Would E.coli still be the number
one cause?
We have to think about in that population.
06:24
Nosocomial were
hospital-acquired infections
those particular patients
may need coverage
for organisms such
as methicillin-resistant
staphylococcus aureus or MRSA.
06:36
So let's review
the bacterial etiologies
of urinary tract infections.
06:40
I want you to pay attention to
these two tables that we have here.
06:43
The table on the left are gram
negative organisms
associated with UTIs.
06:47
The table on the right
are gram-positive organisms.
06:50
And what I'd like you to note
is that look at that first line.
06:54
E.coli by far and
away is the number one cause
of urinary tract infections
and uncomplicated
urinary tract infections.
07:03
It's to a lesser extent.
07:04
We see E.Coli
and complicated UTIs,
but one thing that you should
note with complicated UTIs.
07:11
We tend to see some
of the more obscure organisms
like pseudomonas aeruginosa
and some of the other
enterobacter species as well.
07:19
For a gram positive organisms.
07:20
The most common that we see are
going to be coagulase negative staph
like staff saprophyticus
and about 5 to 20%
of uncomplicated UTIs.
07:28
Less so in our complicated UTIs,
but we have an increase
in enterococcus infections
and complicated UTIs.