Urinary Tract Infection (Clinical Tips) - Dr. Gawad

Mohammed Abdel Gawad MD Neph, ESENeph
Lecturer of Nephrology, School of Medicine, NewGiza University
NephrologyConsultant,Alexandria
Founder of NephroTube.com
Chairof AFRAN Web/Media Committee
ISN African RegionalBoard Member
drgawad@gmail.com
@Gawad_Nephro
Urinary Tract Infection
Clinical Tips

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Talk Outline
• Terminology, routes and predisposing factors
• Diagnosis
• Urine dipstick
• Urine microscopy
• Urine culture
• Acute Uncomplicated Cystitis
• Pyelonephritis
• AsymptomaticBacteriuria
• Catheter-associatedUrinary Tract Infection
• Approaching Candiduria with urinary catheter
• Approaching Candiduria without urinary catheter
• Recurrent UTI
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UTI Classification
Upper UTI
(infection involvingkidney & ureter)
Pyelonephritis
Lower UTI
(infection involvingurinary bladder)
Cystitis
Lower UTI
(infection involvingurethra)
Urethritis
UTI: Complicatedor not
UTI (specifically an infection of the
bladder) in an immunocompetenthost
with normal urinary tract anatomy.
Acute uncomplicated
cystitis (also known as
“simple cystitis”)
UTIs that occur in patientswith severe
immunosuppressionor with significant
anatomicalabnormalities.
ComplicatedUTI
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Route of
Infection
Hematogenous
(bacterial infection from
blood) very rare.
Ascending
(bacterial infection
through urethra)
Hematogenousroute
Ascending route
• The usual mechanism of infection is bacteria
colonizing the urethra or periurethral space migrating
into the bladder and causing an inflammatory
response.
• The bacteria that typically cause this are from the GIT
and are collectively called Enterobacterales; examples
include Escherichia coli, Klebsiella pneumoniae, and
Proteus mirabilis.
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Factors predisposingto UTI
• Females
• Pregnancy
• Previous UTI
• Immunocompromised (e.g. taking
corticosteroids)
• Diabetesmellitus
• Abnormalitiesof the urinary tract
(e.g. kidney stones)
• Instrumentation,e.g. urinary
catheter
• Sexual intercourse
• Use of spermicides (which kill
lactobacilliof the bacterial biofilmsthat
protect urogenitalcells)
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neutrophils and
macrophages
Leukocyte esterase
Lysis
Urine
2008 Jun;51(6):1052-67
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neutrophils and
macrophages
Leukocyte esterase
Lysis
Urine
• Concentrated urine
• High relative density
• Proteinuria
• Glucosuria
• Cephalotine and tetracycline (strong interference)
• Cephalexine (moderate interference)
• Tobramycin (mild interference)
False -ve
2008 Jun;51(6):1052-67
but positive microscopy findings
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neutrophils and
macrophages
Leukocyte esterase
Lysis
Urine
• Alkaline pH
• Low relative density
False +ve
but negative microscopy findings
2008 Jun;51(6):1052-67
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neutrophils and
macrophages
Leukocyte esterase
Lysis
Urine
• Alkaline pH
• Low relative density
False +ve
but negative microscopy findings
2008 Jun;51(6):1052-67
The reported sensitivity of leukocyte esterase for detecting
bacteriuria is variable but it is specific. (i.e. not good negative, but
good positive)
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Gram-negative bacteria,
Enterobacteriaceae
species
nitrate
reductase
Urine
nitrate
nitrite
2008 Jun;51(6):1052-67
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Gram-negative bacteria,
Enterobacteriaceae
species
nitrate
reductase
Urine
nitrate
nitrite
Sensitivity of this test is low, whereas Specificity
is greater than 90% (i.e. not good negative, but good positive)
2008 Jun;51(6):1052-67
One of the limitations of this test is that it would not detect
bacteriuria with organisms that do not have the biochemical ability
to create nitrite such as Enterococci and Pseudomonas species.
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Pyuria
o having ≥10 WBCs/μL in urine is suggestive but not diagnostic of a UTI.
o Pyuria absence is a good negative (negative predictive value more than 85%) but its presence is
not goodpositive
o Therefore, without pyuria it is unlikely that a patient has a UTI.
Granular cytoplasm
and
Lobulated nucleus
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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2008 Jun;51(6):1052-67
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2008 Jun;51(6):1052-67
The absence of WBC casts should not exclude acute pyelonephritis in
the presence of a reasonable clinical suspicion.
Am J Kidney Dis. 2014;64(4):558
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Urine culture
The classic cutoff for a positive urine culture to reflect the presence of bladder
bacteriuria has been > 105 colony-forming units (CFU)/mL, less than this is
considered as contamination.
Urine culture not
indicated in
Urine culture indicated in
most cases of uncomplicated
cystitis
• Signs or symptoms of upper tract disease or systemic illness.
• Atypical symptoms, such as a patient who has dysuria and vaginal symptoms that are
also suggestive of vaginitis.
• Patients at high risk of developing complications, such as those who are
immunocompromised or have urological abnormalities.
• Patients at risk of infection with multidrug-resistant organisms (MDRO), such as those
with a history of infections with MDROs or who have had recent courses of antibiotics or
a recent hospitalization.
• Lack of improvement or progression of symptoms after about 48-72 hours of initial
empiric antibiotics.
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Acute Uncomplicated Cystitis
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Acute Uncomplicated Cystitis
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
This is due to their side-effect profile and to
mitigate the increasing rates of quinolone
resistance. They are reserved for more
serious infections such as pyelonephritis
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The diagnosis of pyelonephritisshouldbe made by:
Clinical assessment The typical symptoms include flank pain, fevers, rigors, nausea, or vomiting
Laboratorytesting Urinalysis and urine culture are recommended for all cases of suspected pyelonephritis
Imaging:
not required for all
cases and can be
reserved for:
▪ cases where the patient is critically ill
▪ not improving on initial therapy
▪ suspected to have an obstruction
▪ suspected to have a complication:
❖ Complications of pyelonephritis include but are not limited to:
o sepsis
o acute renal failure
o renal or perinephric abscess
o kidney stones (eg, staghorn calculi)
o emphysematous pyelonephritis (a serious necrotizing infection).
❖ Computed tomography (CT) scan of the abdomen with intravenous (IV) contrast is typically
the primary mode of imaging in the majority of these cases. Renal ultrasound is less
sensitive than a CT scan but is a reasonable alternative for patients where exposure to
radiation or contrast is of concern.
Pyelonephritis: Diagnosis
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Pyelonephritis: Treatment
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
• In patients who are clinically stable and can
tolerate oral medications.
• The recommended duration for treatment of
pyelonephritis with ciprofloxacin is 7 days,
provided the patient is clinically improving.
Tests of the cure with repeat urine cultures is not recommended www.NephroTube.com
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Definition ASB is defined as ≥105 CFU/mL in a voided urine specimen without signs or symptoms attributable to UTI. This is
regardless of whether pyuria is present.
Treatment: Studies have shown that antimicrobial treatment for the majority of patient populations with ASB does not
confer significant benefit but can increase the risk of antimicrobial resistance or Clostridioides difficile infection.
Main
indications to
treat ASB:
o The first is pregnant women because treatment decreases the risk of pyelonephritis and negative fetal
outcomes.
o The second is patients who will undergo urologic procedures associated with significant mucosal bleeding
and trauma (eg, transurethral surgery of the prostate or the bladder, or percutaneous stone surgery).
ASB in
transplanted
patients:
o Relatedly, most of the data available do not support treatment of ASB in renal transplant patients. This,
however, continues to be studied; currently, because of the lack of data on the immediate transplant period
(1-2 months after transplant), many centers will treat ASB if found coincidently during this time, but they do
not routinely screen for such.
o Patients with solid organ transplants, other than early renal transplant, do not require treatment for ASB.
Asymptomatic Bacteriuria (ASB)
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Diagnosis The CDC surveillance definition of a CAUTInecessitates that patients meet the following3 criteria:
o Indwellingcatheter in place for more than 2 consecutive days in an inpatientlocation.
o Urine culture with no more than 2 organisms present and 1 organism with bacterium of
>105 CFU/mL.
o Presence of at least 1 of the following: fever (38C), suprapubic tenderness, costovertebral
angle pain or tenderness, urinary urgency, urinary frequency, or dysuria.
Treatment o first discontinuingthe indwellingcatheter
o or replacing the catheter (if still needed) if it has been in place for more than 2 weeks.
o A duration of 7 days of antimicrobial therapy is likely sufficient, provided that the patient
improves clinicallyafter starting antimicrobials.
Catheter-associated Urinary Tract Infection
(CAUTI)
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Because urine cultures from long-term indwellingcatheters may reflect the microbiologyof
the catheter’s biofilminstead of the infection in the bladder, obtaininga urine culture from a
newly placed catheter is recommended to guide antimicrobialtherapy.

Approaching Candiduria with urinary catheter
- For patients with indwelling catheters and Candida isolated from urine culture, the catheter should be discontinued (if
possible) and a repeat urine culture obtained to investigate whether Candida is still present.
- If an indwelling catheter is still required, the catheter should be exchanged and a new culture obtained to again assess
for persistence of candiduria.
If Candida is again isolated
the clinician must then determine whether the patient has continued
contamination, colonization, or infection. Note that pyuria is an expected
finding in patients who have indwelling catheters and is not helpful in
delineating colonization versus infection.
imaging as renal ultrasound or CT
abdomen/pelvis is indicated to assess for
obstruction
Treatment of Candida UTI is only indicated in cases of
persistent candiduria in patients who have symptoms
consistent with UTI without an alternative etiology (i.e.,
concurrent bacteriuria).
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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@Gawad_Nephro

Approaching Candiduria without urinary
catheter
- First, a repeat clean catch urine sample should be obtained (or a specimen from the catheter if clean catch is not feasible)
to see if Candida is again isolated.
- If applicable, patients should also be assessed for the presence of concurrent vaginitis.
If Candida is again isolated
imaging as renal ultrasound or CT
abdomen/pelvis is indicated to assess for
obstruction
- Treatment of candiduria is only indicatedwhen patients have signs/symptomsconsistentwith UTI.
- Exceptions to this management approach include patients undergoing urologic procedures and neutropenic patients
for which asymptomaticcandiduria should be treated.
AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Premenopausal
marriedwomen:
o There are associations with recurrent UTIs related to sexual activity related to spermicidal contraceptives;
if a woman is using this form of contraception, changing to a different agent may provide benefit.
o It is not clear that other behavior modifications such as early voiding after sexual intercourse or increased
hydration to precipitate more frequent urination are effective in isolation, but certainly these are low-risk
interventions that are easy to do.
Postmenopausal
women:
o especially those in whom there may be associated incontinence, a pelvic examination to exclude pelvic
floor dysfunction or prolapse is advised.
o If there is no correctable anatomic issue, then vaginal estrogens are a well-tolerated, low-risk intervention
to undertake.
For those who
are unable to
derive benefit
fromup
interventions:
o Postcoital antibiotics can be effective and the most well-studied agent is trimethoprim/sulfamethoxazole.
o Continuous prophylaxis has been shown to be effective in clinical trials, but the efficacy is lost once
prophylaxis is stopped. Further, prophylaxis is not usually 100% effective, so UTIs will likely be less frequent
but still present, and when they occur, the organisms present are likely to have antimicrobial resistance to
the class of prophylactic drug.
o Utilization of supplements such as cranberry extracts and D-mannose have been tried, and some
individuals may find benefit, but the data are mixed
Men: o recurrent UTIs in men are often associated with underlying structural issues leading to urinary
retentionor the presence of an indwellingcatheter.
Recurrent UTI AJKD. 2023 Oct 30:S0272-6386(23)00837-5
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Home messages
• The reported sensitivity of leukocyte esterase for detecting bacteriuria is variable but it is specific. (i.e.
not good negative, but good positive)
• Sensitivity of urine nitrite is low, whereas specificity is greater than 90% (i.e. not good negative, but
good positive)
• Pyuria absence is a good negative (negative predictive value more than 85%) but its presence is not
good positive
• The absence of WBC casts should not exclude acute pyelonephritis in the presence of a reasonable
clinical suspicion.
• Urine culture is not indicated in most cases of uncomplicated cystitis but may be indicated in other
situations.
• Nitrofurantoin, Trimethoprim-sulfamethoxazole, Fosfomycin are 1st line in management of
uncomplicated cystitis.
• Ciprofloxacin is not 1st line in management of uncomplicated cystitis due to their side-effect profile and
to mitigate the increasing rates of quinolone resistance.
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Home messages
• Pyelonephritis: urine analysis & culture are mandatoryfor diagnosis, while imaging is necessary
only in certain indications.
• Asymptomaticbacteriuria should be treated only if pregnant or pre-urosurgery associated with
significant mucosal bleeding and trauma
• Asymptomaticbacteriuria treatment in the first 1-2 months after renal transplant is debatable.
• Catheter ass UTI: remove/replace the catheter, then culture, then antibiotic/7days
• Candiduria: remove/replace catheter is present, obtain new culture, if new culture is positive so
imaging is indicated to assess for obstruction, treat if symptomaticonly, treat if asymptomaticif
patients undergoing urologic procedures and neutropenic patients
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Urinary Tract Infection (Clinical Tips) - Dr. Gawad

Urinary Tract Infection (Clinical Tips) - Dr. Gawad

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