1. Urinary Tract Infections

2. Objectives
Know the predominant organisms causing urinary tract infection in children
Be able to evaluate a pre-school age child with a urinary tract infection
Differentiate between upper and lower urinary tract infections in patients of differing ages
Know the appropriate antibiotic treatment for acute cystitis and the role of imaging

3. Background Overall prevalence of UTI in febrile infants 5%
Recurrent UTIs may lead to:
Renal scarring
HTN
Renal dysfunction and failure
Presence of another source of fever (URI, AOM) does NOT rule out UTI
Parents reporting “foul-smelling” urine does NOT correlate with UTI

4. Host Factors Associated with UTI
Caucasian 2-4x prevalence
Females x prevalence vs circumcised males
Uncircumcised 4x higher than circumcised Males males until 1 year of age
Breastfed Lower rates due to IgA Infants
Familial History Genetic Predisposition
Anatomic GU Reflux most common at 1% prevalence; 40-50% of young children with febrile UTI

5. Circumcised Males > 1 year old <1% 0.01 (1/100)
Based on data from Hoberman, A, et al. Prevalence or urinary tract infection in febrile infants. J Pediatr 1993; and Shaw, KN et al. Prevalence of urinary tract infection in febrile young children in the emergency department. Pediatrics 1998.
Demographic Group
Prevalence
Odds
Circumcised Males > 1 year old
<1%
0.01 (1/100)
Circumcised Males < 1 year old 2%
0.02 (1/50)
African American Females 4%
0.04 (1 in 25)
Uncircumcised Males < 2 year old 8%
0.09 (1/12)
White Females < 2 years old
16%
0.19 (1/5)

6. Host Factors Associated with UTI
Sexual Activity Not well documented; use of spermicidal condoms and jelly associated with E. coli bacteruria
Physiologic Dysfunctional voiding – Abnormality 40% of toilet trained children with first UTI and % with recurrent UTI

7. Symptoms of Dysfunctional Voiding
Withholding behaviors – squatting, leg crossing
Bladder/bowel incontinence – diurnal enuresis
Abnormal elimination pattern – small frequent voids with incomplete emptying
Failure to relax urinary sphincter and pelvic musculature results in overactive detrusor contractions causing bladder-sphincter dyssynergy
It is estimated that 15% of pediatric population have dysfunctional voiding – consider diabetes neurogenic bladder

8. Differential Vulvovaginitis Viral cystitis (eg adenovirus)
Enterbiasis (pinworms)
Urinary calculi
STD
Vaginal foreign body
Epididymitis

9. Evaluation
UTI diagnosis SHOULD NOT be established by a culture of urine collected in a bag
Correct diagnosis requires culture of clean catch, catheterized, or suprapubic tap specimen
Urine dipstick can rule out UTI, but positive result is insufficient to diagnose UTI due to potential for false positives
CBC/CRP are unnecessary

10. Understanding the UA Nitrite
produced by conversion of nitrate by the enzyme nitrate reductase contained by some bacteria, such as E. coli, Klebsiella and Proteus
False positives occur when bacterial overgrowth occurs in the setting of delay prior to lab testing
Urine must remain in the bladder 4 hours to accumulate detectable amount of nitrite, therefore an uncommon finding in young children
Positive nitrite very likely to indicate UTI
Staph saprophyticus does not produce nitrite.

11. Understanding the UA Leukocyte esterase (LE) enzymatic marker for WBCs
suggestive of UTI, however, does not always signal a true UTI.

12. Sensitivity and Specificity of Components of Urinalysis
TEST
SENSITIVITY %
SPECIFICITY %
Leukocyte esterase 83 78
Nitrite 53 98
LE & Nitrite + 93 72
Microscopy: WBCs 73 81
Microscopy: bacteria
LE/Nitrite/micro +
99.8 70

13. Definition of UTI Clean catch Catheterized Suprapubic (gold standard)
> 100,000 organisms of one bacteria
Catheterized
>50,000 cfu/ml in children < 2 yr
If 10,000-50,000 repeat urine cx suggested
>10,000 on repeat  UTI
Suprapubic (gold standard)
Any growth

14. Radiologic Imaging Ultrasound of Kidneys VCUG
Assess for structural anomalies
Urgent ultrasound may be necessary if there is inappropriate response to treatment within hours - rule out obstruction or abscess
VCUG
Rule out vesico-ureteral reflux (VUR)
It has been shown that there is no difference in VUR if VCUG is performed early or late, and is generally acceptable once patient is afebrile.
Patients are placed on antibiotic prophylaxis until completion of imaging studies

15. When to Consider Imaging
Children < 5yr with febrile UTI
Girls under 3 yr with first UTI
Males of any age with a first UTI
Kids with recurrent or resistant UTI

16. When to Hospitalize
Literature states that infants > 2mo can be managed as outpatients on oral meds with close follow-up unless toxic and unable to tolerate oral hydration and meds, in which case hospitalization is necessary

17. Microbiology E. coli accounts for about 80% of UTIs in children.
Other bacteria include: Gram negative species (Klebsiella, Proteus, Enterobacter, and Citrobacter) and Gram positive species (Staph saprophyticus, Enterococcus, and rarely, S. aureus).

18. Treatment Generally treated with: TMP/SFX or cephalosporins for:
7-14 days in children 2mo – 2 years old with cystitis
10-14 days for pyelonephritis
Choice of antibiotic ultimately guided by sensitivity of bacterial isolate
neonates usually hospitalized and treated with IV antibiotics, followed by oral. Generally, patients are switched to oral antibiotics following 2-4 days of IV antibiotics

19. Treatment in Outpatient Setting
TMP/SMX – contraindicated in infants < 2months
Cephalosporins (cefixime) - no enterococcus or pseudomonas coverage
Ceftriaxone if patient noncompliant or emesis is concern
Nitrofuantoin, Amoxicillin – not adequate for pyelonephritis

20. Prophylaxis
TMP/SMX
Nitrofurantoin
Amoxicillin