Urinary tract infection in children
Professor Abdelaziz Elamin
University of Khartoum
Sudan
Introduction
• Urinary tract infections (UTI) is common in the pediatric
age group. Early recognition and prompt treatment of
UTI are important to prevent progression of infection to
pyelonephritis or urosepsis and to avoid late sequelae
such as renal scarring or renal failure.
• Infants and young children with UTI may present with
few specific symptoms. Older pediatric patients are more
likely to have symptoms and findings attributable to an
infection of the urinary tract. Differentiating cystitis from
pyelonephritis in the pediatric patient is not always
possible, although children who appear ill or who present
with fever should be presumed to have pyelonephritis if
they have evidence of UTI.
Pathophysiology
• UTI generally begins in the bladder due to ascending
infection from perineal contaminants, usually bowel flora
such as Escherichia coli. In neonates, infection of the urinary
tract is assumed to be due to hematogenous rather than
ascending infection. This etiology may explain the
nonspecific symptoms associated with UTI in these patients.
• After the neonatal period, bacteremia is not the usual cause
of UTI. The bladder is the initial primary locus of infection
with ascending disease to the kidneys. Bacteremia may then
appear as potential sequelae. Bacterial invasion of the
bladder with overt UTI is more likely to occur if urinary
stasis or low flow conditions exist. This is triggered by
infrequent or incomplete voiding, reflux, or other urinary
tract abnormalities.
Pathophysiology/2
•Even in the absence of urinary tract abnormalities,
cystitis may lead to vesicoureteral reflux, and it may
worsen a pre-existing reflux. Untreated reflux causes
pyelonephritis. Chronic or recurrent pyelonephritis
results in renal damage and scarring that may
progress to chronic renal failure.
•Prevalence varies based on age and sex
Clinical Course
• Generalized bacteremia or sepsis may follow
UTI. Approximately 30% of 1- to 3-month-old
infants with UTI are at risk of developing sepsis.
The risk drops to approximately 5% in patients
older than 3 months.
• If left untreated, simple cystitis may progress to
pyelonephritis. More severe cases have the
potential for kidney damage, which may lead to
hypertension or renal insufficiency.
• Approximately
5-10%
of
children
with
symptomatic UTI and fever develop renal
scarring.
Frequency of UTI
• UTI is more frequent in females than males at all
ages with the exception of the neonatal period,
during which UTI may be the cause of an
overwhelming septic syndrome in male infants
younger than 2 months.
• Uncircumcised males have a higher incidence
than circumcised males. Uncircumcised male
infants have a higher incidence of UTI than
female infants.
Frequency of UTI/2
• Excluding neonates, females younger than
11 years have a 3-5% risk; boys of the
same age have a 1% risk.
• UTI is the source of infection in up to 6-8%
of febrile infants in the first 3 months of
life.
Risk Factors
1.
2.

•
•
•


Bacterial virulence i.e. antigen K and presence of fimbriae
Host factors :
Anatomical
VUR 35% of children with UTI –abnormal insertion of ureters in
the bladder.
Urinary tract obstruction caused by phimosis, meatal stenosis
posterior urethral valves, diverticuli, and ureteric stricture or
kink, and
calculi.
Indwelling catheter
Functional : such as neurogenic bladder in spina bifida
patients, and inappropriate detrusor muscle contractions
Immunologic ; in immune deficiency
Symptoms
 History:
vary with the age of the patient. History is dependent upon
the caregiver in younger children.
 Symptoms in Neonates:
• Jaundice
• Hypothermia or fever
• Failure to thrive
• Poor feeding
• Vomiting
 Symptoms in Infants:
• Poor feeding
• Fever
• Vomiting, diarrhea
• Strong-smelling urine
Symptoms/2
 Preschoolers
• Vomiting, diarrhea, abdominal pain
• Fever
• Strong-smelling urine, enuresis, dysuria, urgency,
frequency
 School-aged children
• Fever
• Vomiting, abdominal pain
• Strong-smelling urine, frequency, urgency, dysuria, flank
pain, or new enuresis
 Adolescents are more likely to have some of the classic
adult symptoms. Adolescent girls are more likely to have
vaginitis (35%) than UTI (17%). Those diagnosed with
cystitis frequently have a concurrent vaginitis.
Physical Examination
• Hypertension should raise suspicion of
hydronephrosis or renal parenchyma disease.
• Costovertebral angle (CVA) tenderness
• Abdominal tenderness or mass
• Palpable bladder
• Dribbling, poor stream, or straining to void
• Examine external genitalia for signs of irritation,
pinworms, vaginitis, trauma, sexual abuse,
phimosis or meatal stenosis .
Etiology
• Bacterial infections are the most common.
• E coli is the most common causing 75-90% of
UTI episodes. Other bacteria include:
• Klebsiella species
• Proteus species
• Enterococcus species
• Staphylococcus saprophyticus
• Adenovirus (rare)
• Fungal in immune compromised patients
Differential Diagnoses
The symptoms of UTI may mimic other conditions
like:
• Sepsis due to bacterimia or viremia
• Falciparum malaria
• Gastro-intestinal disorders
• Renal Calculi with or without obstruction
• Urethritis
• Vaginitis & Vulvovaginitis
Investigations
• Lab Studies:
• Urinalysis: A urine specimen that is found to be positive
for nitrite, leukocyte esterase, or blood may indicate a
UTI.
• Microscopic examination can evaluate presence of
WBCs (>5 per high-power field), RBCs, bacteria, casts,
and skin contamination (e.g., epithelial cells).
• A midstream clean catch is appropriate if the patient is
old enough to cooperate. Clean skin around the urethral
meatus and allow first urine to go into the toilet; then,
collect the specimen in a sterile collection cup.
• In neonates & infants sample obtained by bladder
puncture is the best, but a bag specimen may be used if
the urine bag is removed immediately after urine is
deposited. It is adequate for specific gravity and
chemical parameters but not for culture.
Investigations/2
• Urine cultures should be sent to the laboratory even if
urinalysis results are inconclusive. Approximately 20% of
pediatric patients with UTI have normal urinalyses
results.
• Results are best interpreted with knowledge of the
collection method and results of the urinalysis.
• A clean-catch urine sample with more than 100,000
colony-forming units (CFU) of a single organism is
classic criteria for UTI.
• Judgment must be used in interpreting a clean-catch
specimen that reports any growth. If the specific gravity
of the urine was low, 60,000-80,000 CFU may be
significant.
Investigations/3
• Lower colony counts may be significant if present on a
repeat culture. Contamination with perineal flora may mask
an existing UTI.
• Urinary tract abnormalities may be associated with multiple
organisms.
• Cultures with growth of more than 10,000 pure CFU/ml
from bladder catheterization or >1000 pure CFU/ml from
suprapubic aspiration should be considered significant for
UTI.
• Urine collected in bags is generally not suitable for culture
because of the high incidence of contamination.
• Better results may be obtained if the perineum is cleaned
and dried before the bag is placed and if the collected urine
is removed as soon as the patient voids.
Investigations/4
• Cultures from bagged urine specimens are significant
only if there is no growth. Cultures from bag specimens
should only be used for relatively well children who did
not receive empiric antibiotics for fever. In general,
young infants with high fever should never have a bag
specimen sent for culture given the consequences of
difficult to interpret positive culture.
• Other Lab findings may include:
 Electrolyte abnormalities
 Increased blood urea nitrogen (BUN). Such finding in a child
older than 2 months should raise the suspicion of
hydronephrosis or renal parenchyma disease.
• Any child with proven UTI should have imaging studies
performed to R/O VUR or renal anomalies.
Imaging studies
• Imaging typically is delayed 3-6 weeks after the infection
as part of outpatient follow-up, except in cases in which
urinary tract obstruction is suspected.
• Renal ultrasound
• This study adequately depicts kidney size and shape,
but it poorly depicts ureters and provides no information
on function.
• A renal ultrasound can diagnose urolithiasis,
hydronephrosis, hydroureter, ureteroceles, and bladder
distention and has replaced the intravenous pyelogram
(IVP) in many cases.
• A voiding cystourethrogram (VCUG) adequately depicts
urethral and bladder anatomy and detects vesicoureteral
reflux (VUR).
Imaging studies/2
Nuclear cystography
• This study is good for visualizing the bladder and
detecting VUR, but it does not show the urethra.
• It has only a small fraction of radiation dose (~1%)
compared to fluoroscopic study.
• It can be used for serial follow-up studies and screening
of siblings.
Nuclear cortical scanning
• This study most frequently uses technetium Tc 99m
dimercaptosuccinic acid (DMSA).
• This study detects tubular damage and scarring and
shows the kidney outline, but it does not show the
collecting system.
A The MCU showing a
dilated posterior urethra,
mildly irregular
appearance of the
edge of the bladder
(reflective and
trabeculation) and bilateral
vesicoureteric reflux into
dilated tortuous ureters.
B Hydronephrosis with
'clubbing' of the calyces.
Procedure
• Catheterization of the urinary bladder or
suprapubic bladder aspiration may be required
in patients who cannot provide a midstream
clean-catch urine sample.
• A suprapubic tap is the most invasive diagnostic
procedure, but many practitioners view it as the
criterion standard despite the potential for gross
or microscopic hematuria.
Treatment
• Emergency Department Care: Treatment must be tailored to the
presentation of the patient.
• Septic or toxic patients require aggressive management in the ER.
Intravenous fluid replacement and parenteral antibiotics should be
started after collection of laboratory samples.
• Initially, all ill-appearing patients with febrile UTI should be treated
with parenteral antibiotics and monitored as an inpatient. The ER
consultant or the pediatrician should be informed.
• Oral fluids and medications on outpatient basis may be used for
patients with cystitis who are less seriously ill at presentation.
• Consultation with a urologist is not required at presentation unless
there is evidence of obstruction of the urinary tract.
Antibiotics
• Start antibiotics after urinalysis and culture are obtained.
A 10-day course of antibiotics is recommended, even for
uncomplicated infection. Do not use short-course
therapy in children because it is more difficult to
differentiate cystitis from pyelonephritis. An exception is
the use of short-course therapy in adolescent females
with evidence of cystitis.
• Empiric antibiotics for coverage of E coli, Enterococcus,
Proteus, and Klebsiella species should be started while
waiting the culture & sensitivity results. For cystitis, oral
antibiotic therapy is adequate, but if pyelonephritis is
suspected, a combination of parenteral antibiotics is
recommended. Recent evidence indicates that oral
antibiotics are adequate therapy for febrile UTI in young
infants and children; short-term (fever) and long-term
(renal scarring) outcomes are comparable to parenteral
therapy.
Antibiotics/2
 Amoxicillin
Provides bactericidal activity against susceptible organisms, mainly E.
Coli, but resistance is reported. Administered parenterally and used in
combination with gentamicin or cefotaxime. Pediatric Dose 100-200
mg/kg/d. IV/IM divided q6h.
 Gentamicin
Aminoglycoside antibiotic for gram-negative coverage. Provides
synergistic activity with amoxicillin against gram-positive bacteria including
enterococcal species. Pediatric Dose <5 years: 2.5mg/kg/dose, IV/IM q8h.
>5 years: 1.5-2.5 mg/kg/dose IV/IM q8h.
 Cefotaxime
Third-generation cephalosporin that covers most of the gram-negative
Bacteria, but weak activity against gram-positive organisms. Used as
initial parenteral therapy for pediatric patients with acute pyelonephritis.
May be used for neonates or jaundiced patients. Requires dosing at q6-8h
intervals. Pediatric Dose is 100-200 mg/kg/d IV/IM in divided doses.
Antibiotics/3
 Trimethoprim/sulfamethoxazole
Inhibits bacterial growth by inhibiting synthesis of dihydrofolic
acid. Antibacterial activity of TMP-SMZ includes common
urinary tract pathogens, except Pseudomonas aeruginosa.
Pediatric Dose <2 months: Not recommended >2 months: 510 mg/kg/d PO divided q12h, based on TMP component .
 Cephalexin
First-generation cephalosporin that is useful in simple UTI.
Pediatric Dose 25-50 mg/kg PO q6h; not to exceed 3 g/d.
 Cefixime
Third-generation oral cephalosporin with broad activity against
gram-negative bacteria. Pediatric Dose: 8 mg/kg PO qd; not to
exceed 400 mg/d.
Antibiotics/4
 Norfloxacin
Norfloxacin and Ciproflox acin are potent agents against
gram negative organisms. They are used as second line
treatment or for recurrent UTI.
 Nalidixic Acid
Specific drug for UTI because it has minimal distribution in
tissues and is excreted mainly through the kidneys and
reach high concentration in urine. It should not be used in
children with G6PD deficiency because it may lead to
hemolysis.
Follow-up
• Hospitalization is necessary for the following
individuals:
• Patients who are toxemic or septic
• Patients with signs of urinary obstruction or
significant underlying disease
• Patients unable to tolerate adequate PO fluids or
medications
• Infants younger than 3 months with febrile UTI
(presumed pyelonephritis)
• All infants younger than 1 month with suspected
UTI even if not febrile
Complications
• Dehydration is the most common complication of UTI in
the pediatric population. IV fluid replacement is
necessary in more severe cases. Treat febrile UTI as
pyelonephritis, and consider parenteral antibiotics and
admission for these patients.
• Untreated UTI may progress to renal involvement with
systemic infection (e.g., urosepsis).
• Long-term complications include renal parenchyma
scarring, hypertension, decreased renal function, and, in
severe cases, renal failure.
Take home message
• Most cases of UTI are simple, uncomplicated,
and respond readily to outpatient antibiotic
treatments without further sequelae.
• Appropriate treatment, imaging, and follow-up
prevent long-term sequelae in patients with
more severe infections or chronic infections.
• Mild VUR usually resolves without permanent
damage.
• Any child with proven UTI should have imaging
studies performed to R/O VUR or renal
anomalies.