4. Prevalence and Etiology
The prevalence varies with age.
Most common in children under age 1 yr
A febrile symptomatic UTIs in children over age 1 yr is~8%
In febrile infants is 7%.
During the first yr of life, Male:Female ratio is 2.8 : 5.4.
Beyond 1-2 yr, there is a female preponderance, Male:Female ratio of 1 : 10
4
5. Much more common in uncircumcised males - 20% in febrile uncircumcised
males under age 1 yr.
In females, the first UTI usually occurs by the age of 5 yr, with peaks during
infancy, toilet training, and onset of sexual activity.
5
6. Primarily by colonic bacteria -Escherichia coli(54–67% ) ,Klebsiella spp ,Proteus
spp, Enterococcus, and Pseudomonas
Others - Staphylococcus saprophyticus, group B streptococcus, Staphylococcus
aureus, and Salmonella spp ,Candida spp ,adenovirus
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7. Pathogenesis and Pathology
Nearly all UTIs are ascending infections
Fecal flora, colonize the perineum, and enter the bladder via the urethra.
In uncircumcised males, the bacterial pathogens arise from the flora beneath the
prepuce
Rarely, renal infection occurs by hematogenous spread
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8. Defect in anti reflux mechanism that prevents urine in the renal pelvis from
entering the collecting tubules
Passive anti reflux mechanism –passive compression of the ceiling of intravesical
ureter against underlying detrusor muscle ,intravesical ureter length and diameter
Active anti reflux mechanism –active shortening of the longitudinal muscle layer
of transmural and submucosal ureter –active valve
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10. The presence of bacterial pili or fimbriae on the bacterial surface
Two types of fimbriae, type I and type II.
type II - Mannose resistant, P fimbriae are more likely to cause pyelonephritis
Between 76% and 94% of pyelonephritogenic strains of E. coli have P fimbriae,
compared with 19–23% of cystitis strains.
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11. Classification and Clinical Manifestations
Pyelonephritis and cystitis.
Focal pyelonephritis (lobar nephronia) and renal abscesses -less common.
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12. Pyelonephritis
Involvement of the renal parenchyma is termed acute pyelonephritis
No parenchymal involvement, the condition may be termed pyelitis.
Pyelonephritic scarring
Acute lobar nephronia (acute lobar nephritis) - localized renal parenchymal, more
commonly occurs in older children, early phase of renal abscess .
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13. Any or all of the following: abdominal, back, or flank pain; fever ,malaise,
nausea,vomiting ,and, occasionally, diarrhea.
Fever may be the only manifestation:a temperature > 39°C without another source
, lasting more than 24 hr for males and more than 48 hr for females
Newborns - poor feeding, irritability, jaundice, and weight loss.
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14. Renal abscess - following hematogenous spread with S. aureus or pyelonephritic infection caused by the
usual uropathogens.
Most abscesses are unilateral , right sided and can affect children of all ages
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15. Perinephric abscess
Diffuse throughout the capsule and is not walled off
Contiguous infection in the perirenal area (e.g., vertebral osteomyelitis, psoas
abscess) or pyelonephritis that dissects to the renal capsule
The most common organisms -S. aureus and E. coli.
Abnormal findings may not be seen on urinalysis or culture.
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16. Xanthogranulomatous pyelonephritis
Granulomatous inflammation with giant cells and foamy histiocytes
As a renal mass or an acute or chronic infection.
Renal calculi, obstruction, and infection with Proteus spp. or E. coli
Usually requires total or partial nephrectomy.
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17. Cystitis
Only bladder involvement
Dysuria, urgency, frequency, suprapubic pain, incontinence, and possibly
malodorous urine.
Does not cause high fever and does not result in renal injury.
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18. Uncomplicated cystitis — limited to the lower urinary tract ,children older than
two years with no underlying medical problems or anatomic or physiologic
abnormalities.
Complicated cystitis — Coexisting upper UTI, multiple-drug resistant
uropathogens, or hosts with special considerations ( Anatomic or physiologic
abnormality of the urinary tract, indwelling bladder catheter, malignancy, diabetes)
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19. Acute hemorrhagic cystitis
Uncommon in children
E. coli ,adenovirus types 11 and 21( more common in boys; it is self-limiting, with
hematuria lasting approximately 4 days )
Patients receiving immunosuppressive therapy -adenoviruses and polyomaviruses
(i.e., JC virus and BK virus)
Eosinophilic cystitis or interstitial cystitis
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20. Diagnosis
Suspected based on symptoms or findings on urinalysis, or both
Urine culture is necessary for confirmation and appropriate therapy
Ways to obtain a urine sample-toilet-trained children(a midstream urine sample) ,
In uncircumcised males(the prepuce must be retracted), not toilet trained - a
catheterized or suprapubic aspirate urine sample
If the culture shows > 50,000 colony-forming units/mL of a single pathogen
(suprapubic or catheter sample) and the urinalysis has pyuria or bacteriuria in a
symptomatic child.
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22. Microscopic hematuria - acute cystitis
WBC casts
Pyuria -A WBC count on urinalysis above 3-6 WBCs/high-power field is
indicative of infection
Sterile pyuria - positive leukocytes, negative culture,
May occur in partially treated bacterial UTIs, viral infections, urolithiasis, renal
tuberculosis, renal abscess, urinary obstruction, urethritis, inflammation near the
ureter or bladder
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23. Refrigeration is a reliable method of storing the urine until it can be cultured
Leukocytosis and neutrophilia are noted on the complete blood count
An elevated serum erythrocyte sedimentation rate, procalcitonin level, and C-
reactive protein are common
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24. Bacteremia - 3–20% of patients and is most common in infants less than 90 days
old and in any child with obstructive uropathy.
Atypical features - failure to respond with in 48 hr of appropriate antibiotics, poor
urine flow, an abdominal flank or suprapubic mass, non–E. coli pathogen,
urosepsis, and an elevated creatinine level.
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25. Imaging Findings
Imaging is not needed to make the clinical diagnosis of UTI or pyelonephritis
Acute lobar nephronia or renal abscess
Ultrasound is the first-line
CT scan
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27. The AAP practice parameter recommends initial ultrasound of the kidneys, ureters,
and bladder for children 2-24 mo with a first episode of UTI.
VCUG is indicated only if the ultrasound study indicates hydronephrosis, scarring
or other findings suggestive of reflux or obstructive uropathy, or if the patient has
other atypical complex features , recurrent febrile UTI
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28. Treatment
Acute cystitis
3- to 5-day course of therapy with trimethoprim-sulfamethoxazole (TMP-SMX)
(6-12 mgTMP/kg/day in 2 divided doses)
Nitrofurantoin (5-7 mg/kg/24 hr in 3-4 divided doses)
Amoxicillin (50 mg/kg/24 hr in 2 divided doses)
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29. Acute febrile UTIs
7-14 days , oral and parental routes are equally efficacious
Dehydrated, are vomiting, are unable to drink fluids, have complicated infection,
or in whom urosepsis is a possibility should be admitted to the hospital for
intravenous (IV) rehydration and IV antibiotic therapy
Ceftriaxone (50 mg/kg/24 hr, not to exceed 2 g) or cefepime (100 mg/kg/24 hr q
12 h) or cefotaxime (100-150 mg/kg/24 hr in 3-4 divided doses)
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30. Oral 3rd-generation cephalosporins
Urine cultures are typically negative within 24 hr of initiation of antibiotic therapy
Acute lobar nephronia is treated with the same antibiotics as pyelonephritis. The
duration of treatment is recommended for 14-21 days.
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31. Renal or perirenal abscess or with infection in obstructed urinary tracts- surgical or percutaneous
drainage in addition to antibiotic therapy
Long-term antibiotic prophylaxis - Neuropathic bladder, urinary tract stasis and obstruction, severe VUR
, and urinary calculi.
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32. Long term consequence
Kidney loss - 10–20% of cases of renal abscess
Arterial hypertension
End-stage renal insufficiency
The rate of renal scarring increases between days 2 and 3 of fever, number of
episodes of pyelonephritis and with the grade of reflux.
32
33. Prevention of Recurrences
Bowel and bladder dysfunction
Constipation
Intermittent clean catheterization
Treat underlying causes
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Risk factor for renal insufficiency or end-stage renal disease- only 2% of children with renal insufficiency report a history of UTI.
grade III, IV, or V VUR
and a febrile UTI, 90% have evidence of acute pyelonephritis on renal
scintigraphy or other imaging studies , toilet training because of bowel–bladder dysfunction
Pyuria may be less likely with certain pathogens (eg, Enterococcus species, Klebsiella species, P. aeruginosa)
Positive nitrites on dipstick analysis; nitrites are produced by Enterobacteriaceae (eg, E. coli, Klebsiella, and Proteus)
TMP-SMX prophylaxis for patients with a history of UTI and diagnosed VUR
