Urinary Tract Infections

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

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

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

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)

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

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

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

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

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.

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

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

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

Radiologic Imaging Ultrasound of Kidneys VCUG 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

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

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

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).

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

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

Prophylaxis TMP/SMX Nitrofurantoin Amoxicillin