Transcript asymptomatic UTI - University of Nevada, Reno School of Medicine

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9 million doctor visits/year!
Customary urine test is the dip stick and the mid-stream culture of
voided urine. Up to 77% of cystitis cases are cultured
Traditionally- >100,000 (10⁵)CFUs was called diagnostic of either
UTI (bladder infection present) or asymptomatic bacteruria.
More recently as little as 100 CFUs in a voided sample has been
positively correlated with coliform (such as E. coli) bladder infection
The problem with this cut off: Many labs will call 0 to 10,000 CFUs
(<10⁴) as a negative culture
The way the urine test is done, diluting
out the urine 1000 times, there may be
no growth on the agar plates despite a
bladder infection being present
What does the results of the urine culture tell you ?
202 paired samples of mid stream collected urine cultures and catheterized bladder cultures in young
woman who had symptoms of uncomplicated cystitis, no features of pyelonephritis
70% of bladder cultures positive
78% of voided mid-stream cultures positive
As few as 10 CFUs of mid-stream cultures of E. coli or Klebsiella pneumoniae– highly correlated with a
true bladder infection ( 93% PPV).
In contrast – 22% of mid- stream cultures grew enterococcus or Group B strep- at even 100,000 (10⁵
CFUs) – there was no correlation with bladder cultures- These bugs were not found in the corresponding
bladder culture, but E.coli was still cultured in the bladder (but not in the mid-stream culture) in 62% of
these cases !
Take Home Message:
I. a young woman with classic cystitis symptoms can have a documented bladder infection, but her
midstream urine culture can still be a false negative test ( too few CFUs to be detected on standard urine
cultures)
II. Positive mid-stream cultures for enterococcus and Group B strep are most likely contaminants
III. In uncomplicated cases- obtaining cultures as a guide to therapy can be counter productive: either not
treating patients with actual infection, or treating patients for the wrong bacteria.
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Ask the patient “do you feel like you have a bladder
infection- do you have both a sense of urgency and burnig
when you urinate?”
Do a dip stick and treat only if leukocytes or nitrite positive?
Send the urine for culture, wait 2 days, and treat the patient
only if >100,000/ml colonies
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Symptoms only: +dysuria, +frequency, no discharge or
irritation:***90% chance of cystitis***
Dipstick: leukocyte esterase + and/or nitrite + only 75%
sensitive, so symptoms more important even if dip is negative
Culture:10⁵ (100,000) bacterial CFU- traditional criterion of
UTI- 50% sensitive -will miss up to half of cases of UTI –
counts of 100 to 10,000 colonies – all at levels that may be
called as “no growth” by micro lab. Least sensitive diagnostic
test
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**Rarely progresses to severe disease even if untreated:
goal is to ameliorate symptoms
In selecting therapy, efficacy as well as “ecologic collateral
damage” (selecting for antibiotic resistant bacteria, C. difficile
colitis) should be considered equally- fluoroquinolones
should be avoided, except in pyelonephritis
Nitrofurantoin, Septra, fosfomycin are therefore first line
agents
New Study- still >50% of Rxs are for Cipro, most of the time
for > than 3 days. Septra #2, nitro #3 , fosfomycin-no Rx
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Definition: presence of bacteria >100,000
cfu/ml in urine of an individual without signs
or symptoms of UTI.
This definition is independent of the presence
or absence of pyuria, odor, cloudy urine
Very Common:
i. Young healthy women : 3 to 5%
i.
Pregnant women: 2 to 9.5%
ii.
Women aged 65-80 years: 18 to 43%
iii. Women > 80 years: up to 43%
iv. Men 65-80 years: 2 to 15%
 Causes:
Obstructive uropathy, neuromuscular
disease, perineal soiling in dementia, etc
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Traditional teaching:
the presence of bacteriuria defines a population at
risk, therefore:
Eliminating the “asymptomatic UTI” (oxymoron)
minimizes the risk for a clinically symptomatic
disease
Modern Teaching:
 NO benefit to treatment (except in pregnancy and
before urologic procedure). Term changed to
“asymptomatic bacteriuria”
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3 to 5% of young women have ABU
What role does this have in recurrent UTI’s? Many women get
follow-up urine studies and re-treatment after initial therapy
for UTI.
Study in Clinical Inf. Disease -9/15/2012:
673 healthy non-pregnant woman followed after first UTI for one year.- all
were treated again at any time if had symptomatic UTIs. urine cultures were
also obtained at 3, 6 and 12 months-if positive but if patient asymptomatic
only half were treated, other half were not
Results after one year of observation:
Those treated for ABU- 46.8% had a symptomatic UTI later
during the year
Those not treated for ABU- only 13.1% had another UTI!
Conclusion: The paradoxical result was increased incidence of
symptomatic UTIs in patients given antimicrobials for
asymptomatic bacteruria!
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Bacterial interference- the inability of pathogenic
bacteria to set up a bladder infection due to
blockage by commensal bacteria colonizing the
bladder- was disrupted by the treatment of ABU.
Conclusion :The human microbiome is a potent
defense mechanism against superinfecting
pathogenic bacteria. Applies to the bladder, as well
as the GI tract and other sites.
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Antibiotic treatment of ASB does not reduce frequency of
symptomatic UTI
Treatment of ASB in diabetes does not reduce adverse
outcomes, improve glucose control, or reduce symptomatic
UTIs
It does lead to untreatable drug resistant bacteria, c.diff,etc
Only exceptions are pregnancy where asymptomatic
bacteriuria is associated with pyelonephritis, growth
retardation, neonatal death… and patients undergoing
urologic procedures (such as prostate bx)
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Many older patients get screening u/a’s and reflex cultures even
when they don’t have urgency and burning symptoms. They are
then treated for a “UTI”. This is a too common mistake…
“older patients should not be tested or treated for UTI unless
they have symptoms”
If you are treated for a true UTI: no follow-up test of cure should
be performed
Antibiotics:
have side-effects
can cause future problems like yeast infection and colitis
lead to drug resistant bacteria
are a waste of money
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Think twice before ordering a urine culture- go by symptoms
and signs. Only culture in possible pyelonephritis, unclear
diagnosis, complicated cases or treatment failure
Consider Macrodantin or Septra as first line therapy,
quinolones if they are ill
Mid-stream culture results with enterococcus and GBS can be
deceiving – rarely cause of UTI. Most likely still E. coli
If the patient is asymptomatic –if it ain’t broke, don’t fix it!