Urinary Tract Infections

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 2-4x 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. 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.

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 80% 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

13. Definition of UTI • Clean catch • > 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 • Assess for structural anomalies • Urgent ultrasound may be necessary if there is inappropriate response to treatment within 24-48 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