Post on 12-Jan-2016
Approach to the Children with Urinary Tract Infection
By
Seyed Taher Esfahani,MD
Professor of PediatricsTehran University Of Medical
Sciences
Definition of UTI
UTI is defined by the presence of bacteria
in bladder urine
DEFINITION OF URINARY TRACTINFECTION
The reference standard for urinary tract infection (UTI) is the isolation of a pure growth of bacteria
in an uncontaminated sample of urine using semiquantitative culture methods
The Importance of Pediatric UTIS
UTIS are common in children
UTIS may have nonspecific sign and symptoms
UTIS have tendency to recur
UTIS can lead to renal damage
Prevalence
• UTIs are relatively common in infants and
young children.• The risk before puberty is 3–5% in girls
and 1–2% in boys .• In young febrile infants aged less
than 24 months the prevalence is 3–5%.• Prevalence is different depending on age and
gender.
Pathogenesis of UTI
UTI is most often an ascending process
except:
During first 8-12 weeks of life
Immunocompromised children
Bacteriemia from an extra urinary site:
skin ,heart , gastrointestinal, skeleton
E.Coli
E.Coli
BLADDER CONTMINATION
BLADDER INFECTION
(Vesicoureteral reflux) ( Vesicoureteral reflux)
PELVICALYCEAL CONTAMINATION
RENALMEDULIARY CONTAMINATION
RENALINFECTION
REFLUX NERPHROPATHY
( Intrarenal reflux)
Bacterial inoculation of renal parenchymaBacterial inoculation of renal parenchyma
Complement activationComplement activation
Chemo taxis - opsonizationChemo taxis - opsonization
PhagocytosisPhagocytosis…………..................………….. IntravascularIntravascular
GranulocyteGranulocyte
aggregationaggregationSuper oxide releaseSuper oxide release
Tubular cell deathTubular cell death
Interstitial invasionInterstitial invasion
RENAL SCARRENAL SCAR
Immune responseImmune response
Bacterial killingBacterial killing
LysozymeLysozyme
ReleaseRelease
FocalFocal
ischemiaischemia
Classification of UTI
1- symptomatic:
acute pyelonephritis
acute cystitis
unspecified UTI
2- Asymptomatic bacteriuria
Approach to the children with UTI
1-Diagnosis of UTI
2-Determination of the site of infection
3-Search for the cause of UTI
4-Treatment
•False positive diagnosis of UTI may lead to unnecessary treatment ,invasive and expensive clinical and radiological examinations
•False negative diagnosis of UTI increases risk
of scarring, hypertension, complications of pregnancy and end stage renal disease
Methods to Obtain Urine Specimens
• The gold standard for obtaining urine in an infant is by suprapubic aspiration. Complications are rare
with the use of ultrasound guidance .• Urinary catheterization is also a very reliable method for obtaining urine without contamination,• Clean-catch mid-stream urine specimens can be collected in toilet-trained children.• The collection of urine in ‘‘collection bags’’ adhesively attached to the the perineal area
The American Academy of Pediatrics
The collection of urine in‘‘collection bags’’ adhesively attached to the the perineal area has no role in the diagnosis of childhood UTIs. The high contamination rate, with ‘‘false positive’’ rates as high as 86% may lead to unnecessary hospitalizations, and/or inappropriate clinical and radiological testing.the American Academy of Pediatrics
Suprapubic aspiration
Suprapubic aspiration
Bacteria that Cause UTI in Children
• E.Coli 60-80%• The other common
bacteria are:
Proteus, Klebsiella, Staphylococcus saprophyticus,
Enterococcus, and Enterobacter
Urinalysis for Immediate DiagnosticInformation
Dipstick testing: nitrite, leucocytes
protein and blood
Microscopic examination: WBC, RBC ,
Bacteria, Cast
Localization of the UTI(1)
• The differentiation between upper(pyelonephritis)
and lower (cystitis) UTI is very important.• It particularly has major clinical implications in
young children. The risk of renal scarring is
significant with pyelonephritis, and not a
concern with cystitis.
Localization of the UTI(2) Clinical signs
Pyelonephritis:
high fever, chills, back or flank pain,
renal tenderness, varied gastrointestinal
symptoms: diarrhea, vomiting, and
nausea, In addition, neurological
symptoms such as irritability, and
seizures (particularly with high fever)
may exist.
Localization of the UTI(3) Clinical signs
Bacterial cystitis:
There is rarely fever >38 Common findings include low grade
abdominal pain and bladder/voiding symptoms
such as frequency, pain with micturation,
suprapublic discomfort, difficulty in voiding
(retention) or hesitancy, urgency, and enuresis.
Specific Clinical Signs of UTIs in Neonates and Infants
The symptoms are nonspecific and require a high degree of clinical suspicion. They include fever, poor feeding, failure to thrive, abdominal pain, haematuria, and malodorousurine. Jaundice may be an early diagnostic sign of UTI in infancy
• unexplained fever
Localization of the UTI(4)Biological Tests
• decreased renal concentrating capacity in pyelonephritis• Specific antibodies to the infecting bacteria• An elevated erythrocyte sedimentation rate, a positive C-
reactive protein,• An elevated peripheral WBC count with an increased
absolute neutrophil counts• Recently a high procalcitonin concentration was
described as a validated predictor of acute pyelonephritis
Serum procalcitonin
• Procalcitonin is an acute inflammatory marker with a sensitivity of 70-95% and a specificity that approaches 90% for renal involvement compared with results of DMSA scan in infants and children with febrile UTI. Although less sensitive than CRP, procalcitonin is more specific for the diagnosis of acute pyelonephritis. Procalcitonin values are better correlated with long-term renal scarring than CRP.
Serum procalcitonin
• Procalcitonin levels near 0.5 ng/mL may not consistently correlate with acute pyelonephritis. As procalcitonin levels increase, the severity of renal lesions on DMSA increases.
• Higher levels of procalcitonin predict VUR in infants and children at the onset of pyelonephritis
Serum and urinary interleukin (IL)-6 and IL-8
Serum and urinary interleukin )IL(-6 and IL-8 are correlated with renal involvement in infants and children with UTI with high sensitivity )81-88%( and acceptable specificity )78-83%(. These markers are not reliable in neonates with suspected acute
pyelonephritis.
Imaging Tests in Localizing the Site of Infection
1-Renal cortical scintigraphy
2-Renal ultrasound
3 -Computed Tomography
4-Magnetic resonance Imaging
Imaging of pyelonephritis
RUS and IVU are relatively insensitive for
detection of pyelonephritis
Radionuclide cortical scan, Computed tomography,
magnetic resonance imaging are
more sensitive
Application of 99mTc-DMSA
• 99mTc-DMSA is the gold standard for the identification of
pyelonephritis and renal scars• Determining split renal function• To identify and character renal infarcts
horseshoe kidney
pelvic kidney
crossed fused ectopia
National institute of Health and Clinical Excellence (NICE): Clinical Guideline, August 2007
The use of DMSA scintigraphy scanning is only recommended by the NICE clinical guidelines in situations when it is clinically important to confirm or exclude acute pyelonephritis, and when the power Doppler ultrasound is not available or the diagnosis still cannot be performed
guidance.nice.org
National institute of Health and Clinical Excellence (NICE): Clinical Guideline, August 2007
Despite a large body of published literature,
the role of radionuclide renal scans in the clinical management of the child with UTI still is unclear. Most of the time such imaging has no role in the specific management of childhood UTIs.
guidance.nice.org
Factors that may complicate interpretation of 99mTc-DMSA
• Fetal lobulation
• The splenic impression
• The relatively decreased uptake of the poles of normal kidney
Causes of defects in DMSA
• Acute pyelonephritis • Renal scars• Cysts• Hydronephrosis• Infarcts• Masses• Dysplastic half of a duplex kidney• Proximal tubulopathies
DMSA
• Planar scintigraphy
• Single photon emission computed
tomography (SPECT)
SPECT Cortical Scintigraphy
• Superior sensitivity for detecting renal scars• Higher rates of false positive results• The increased imaging time with SPECT may
necessitate sedation
Split renal function in DMSA scintigraphy
Normal split function = 50% ± 6%
Renal Ultrasound
Most of the time, conventional renal ultrasound is insensitive for the diagnosis of pyelonephritis.
Signs of pyelonephritis include focal or diffuse renal enlargement, an abnormal cortical echogenicity mostly areas of increased echogenicity which may mimic a renal mass
Renal Ultrasound
•Power Doppler ultrasound is more sensitive
than gray scale ultrasound:
“Pyelonephritis is associated with renal
ischemia. It is seen as a hypovascular
zone in renal cortex”.
Normal Kidney
Gray-scale ultrasound shows diffuse enlargement of the left kidney, which measures 10.3 cm, and a
loss of corticomedullary differentiation
Pyelonephritis. Transverse gray-scale sonography of the right kidney demonstrate two wedge-shape areas of decreased echogenicity (arrow)
Renal abscess
Renal abscess Longitudinal gray-scale ultrasound of the right kidney reveal presenceof a well-defined hypoechoic lesion
Renal abscess. transverse (B) gray-scale ultrasound of the right kidney reveal presence
of a well-defined hypoechoic lesion (A) near the superior pole
Fungal Ball
Power Doppler interrogation shows decreased perfusion to the lower pole of
the left kidney
Pyelonephritis. Transverse gray-scale (A) and color flow Doppler (B) sonography of the right kidney demonstrate absence of colorflow, consistent with multifocal pyelonephritis.
Renal abscess power Doppler image (C) demonstrates an increased peripheral vascularity
Power Doppler ultrasound. Triangular area of cortical ischemia which is well correlated with the
results of DMSA Scintigraphy
Computed Tomography
The features of pyelonephritis by CT have been well described:
After intravenous contrast, areas of infected renal parenchyma have decreased contrast enhancement due to the renal ischemia, whereas normal renal parenchyma becomes brighter
CT:Right kidney is markedly enlarged andhas a wedge-shaped area of low attenuation
Enhanced CT at the level of the kidneys demonstrates an area in the posteromedial aspect of the right kidney with diminished enhancement(arrow), consistent with the clinical suspicion of pyelonephritis.
Magnetic resonance imaging After IV gadolinium contrast the lesions of pyelonephritis
remain bright and the normal renal parenchyma is dark.
MRI / Acute pyelonephritis
Note clumps of small focal lesions irregularly distributed about kidney. Some elevated.
Acute pyelonephritis.
Acute Pyelonephritis
Acute Pyelonephritis
Diagrammatic representation of features of renal scars seen in IVU
Search for the Cause of UTI
• Anatomical abnormalities: urinary tract obstruction, nephrolithiasis,
vesico-ureteral reflux
• Functional disturbances: Voiding dysfunction
Traditional goals of performing imaging in a child with UTI
to detect urologic abnormalities:
VUR, obstructive uropathy,
bladder dysfunction
to detect renal parenchymal damage
Imaging studies in children with UTI
Renal ultrasonography )RUS(
Voiding cystourethrography )VCUG(
Radionuclide cystography ) RNC(
Scintigraphic rénal imaging
)DTPA,DMSA(
Advantages and disadvantages of RUS
1- RUS primarily provides an anatomic evaluation
and is used to seen renal anomalies and
hydronephrosis, renal parenchymal
abnormalities, urethral dilatation bladder wall
thickening ,ureterocells or calculi 2-RUS is not sensitive for focal or general
scarring 3- Normal RUS dose not exclude VUR.
VCUG or RNG?RNG:
1- lower radiation dose
2- Continuous monitoring during study
for reflux
3- Dose not provide any anatomic evaulation
of bladder or urethra
4- Reflux grading is not accurate
Grading of reflux
International classification of vesicoureteral reflux
Grades of Reflux
VUR is benign(1)
• Natural tendency of VUR to resolve spontaneously• The historical studies showing that VUR is much more common, even among healthy children,• Evidence supporting the role VUR leading to pyelonephritis is controversial• The unanimous conclusion of recent meta-analyses on the treatment of VUR has been that surgical abolishment of VUR, compared with microbial UTI prophylaxis and
spontaneous resolution of VUR, has the same risk of new renal parenchymal injury or recurrent non-febrile UTI.
VUR is benign(12)
• The antimicrobial prophylaxis of recurrent UTI is controversial too, and it may have unpleasant short-term side effects and increase the antimicrobial resistance of bacteria
• In one randomised prospective study comparing continuous, intermittent or no treatment with antimicrobials in children with VUR, there was no difference between the groups studied in the risk of recurrent UTI or renal parenchymal injury.
Conclusions:Vesicoureteral reflux is a fairly common phenomenon that can be associated with congenital renal dysplasia.Vesicoureteral reflux does not markedly increase the riskof recurring UTI or new acquired renal scars. The surgical correction of VUR does not prevent recurrences of nonfebrile UTI or new renal scars. In some children VUR is a symptom of developmental maturation defect of the “uretero-vesical valve.
VUR is not benign
• VUR predisposes to UTI and renal scars
• There is not an age limit for renal scarring
• Scarring can be prevented
VUR is not benignConclusion
I believe it may be possible to reduce therate and extent of renal scarring in future by altering our approach to infant and childhood UTIs, with more prompt diagnosis and treatment and an awareness of the potential hazard that having VUR may cause in this setting. The hope is, that by doing this, we will reduce the numbers of adults with hypertension and renal failure in the nextgeneration of adults.
Treatment of UTI
• First: empiric treatment
• Then: according to the result of culture
Treatment of Pyelonephritis
• Completely intravenous treatment
• Initial 3-4 days IV treatment followed by oral treatment
• Completely oral treatment (except high risk children)
Indications for hospitalization
• Age <2 months • Clinical urosepsis or potential bacteremia • Immunocompromised patient • Vomiting or inability to tolerate oral medication • Lack of adequate outpatient follow-up (eg, no
telephone, live far from hospital, etc.) • Failure to respond to outpatient therapy