Urinary tract infections in children and adolescents

To see contributor disclosures related to this article, hover over this reference: [1]

Physicians may earn CME/MOC credit by reading information in this article to address a clinical question, and then completing a brief evaluation, in which they will identify their question and report the impact of any information learned on their clinical practice.

AMBOSS designates this Internet point-of-care activity for a maximum of 0.5 AMA PRA Category 1 Credit(s)™. Physicians should claim only credit commensurate with the extent of their participation in the activity.

For answers to questions about AMBOSS CME, including how to redeem CME/MOC credit, see "Tips and Links" at the bottom of this article.

A urinary tract infection (UTI) is an infection of the bladder, urethra, ureters, and/or kidneys and is a common infection in infancy and childhood. Risk factors include congenital anomalies of the kidneys and urinary tract (CAKUT), female sex, lack of circumcision in young boys, and bladder and bowel dysfunction. As in adults, the most common causative pathogen is Escherichia coli. Children and adolescents often present with classic symptoms of UTI (e.g., dysuria, urinary frequency). However, nonverbal and/or young children often have nonspecific symptoms, which may include fever, irritability, poor feeding, and new-onset urinary incontinence. Diagnosis is based on symptoms and urinalysis and urine culture results. Imaging is not routinely required for diagnosis but is used to evaluate for suspected acute complications (e.g., renal abscess) and underlying structural anomalies, such as vesicoureteral reflux (VUR). The first-line imaging modality is renal and bladder ultrasound (RBUS); voiding cystourethrography (VCUG) or voiding urosonography (VUS) is performed if there is concern for structural anomalies. Treatment of pediatric UTIs involves antibiotics (oral or IV) and management of any underlying causes. Recurrent UTIs are common in children, and patients and/or their caregivers should be educated on preventive measures. Complications of pediatric UTIs, especially if severe or recurrent, include pediatric sepsis, renal scarring, chronic kidney disease, and hypertension.

UTI in adults is discussed in a separate article; see “Urinary tract infections.”

• UTIs are common in children: Up to 7% of girls and 2% of boys are diagnosed with a UTI by 6 years of age. [2]
• < 12 months of age: ♂ > ♀ [3]
• ≥ 12 months of age: ♀ >> ♂ [3]

Epidemiological data refers to the US, unless otherwise specified.

Pathogens [3][4]

• Bacterial
  • E. coli (in up to 90% of cases)
  • Klebsiella pneumoniae
  • Proteus mirabilis [3]
  • Enterococcus faecalis
  • Enterobacter species
  • Rarely: Pseudomonas aeruginosa, group B Streptococcus, Staphylococcus aureus [4]
• Nonbacterial
  • Viral: adenovirus, Enterovirus, Echovirus, Coxsackievirus. [4]
  • Fungal (rare): Candida, Cryptococcus neoformans, Aspergillus [4]

UTIs caused by a pathogen other than E. coli are considered atypical pediatric UTIs. [5][6]

Risk factors for pediatric UTI [3]

• All ages
  • Female sex
  • Personal or family history of CAKUT or VUR
  • Known renal scarring
  • Bowel and bladder dysfunction (e.g., chronic constipation) [2][7]
  • Instrumentation of the urinary tract [3]
• Children ≤ 24 months of age
  • Uncircumcised boys [8][9][10]
  • Age < 12 months
• Children > 24 months of age and adolescents
  • Kidney stones
  • Diabetes
  • Sexual activity

Although uncircumcised young boys are at an increased risk for UTIs, the preventative effect of circumcision on UTI development is not considered sufficient to recommend circumcision for all patients. [11]

By location

• Lower UTI: infection of the bladder (cystitis) and/or urethra
• Upper UTI: infection of a kidney (pyelonephritis) and/or ureter

By severity

• Uncomplicated UTI: a UTI that follows a typical clinical course, responds to antibiotics within 72 hours of administration, and occurs in a patient without existing urinary tract abnormalities or chronic medical conditions [3]
• Atypical pediatric UTI: a UTI in a patient with features suggesting an underlying pathology or complicated infection [2][3][6]
  • UTI in a neonate
  • Severe symptoms (e.g., pediatric sepsis, poor urine stream, ↑ creatinine)
  • Identified pathogen is not E. coli
  • Persistent symptoms despite 48–72 hours of antibiotics
  • Associated complication (e.g., renal abscess)
  • Personal or family history of urinary tract abnormalities (e.g., high-grade VUR, other CAKUT, renal scarring) [3]
  • Abdominal or bladder mass

• Features of lower UTI
  • Urinary frequency
  • Dysuria
  • Urinary urgency
  • Suprapubic pain
• Features of upper UTI
  • Flank pain
  • Fever [2][3]
• Nonspecific symptoms (may be reported by caregivers of young children) [2][3][12]
  • New-onset urinary incontinence (if toilet trained)
  • Irritability
  • Crying when urinating
  • Poor feeding
  • Malodorous urine
  • Neonates: jaundice, hypothermia [8][13]

Symptoms of a pediatric UTI may be nonspecific; fever may be the only sign, particularly in infants. Neonates may present with hypothermia. [2][3]

Acute pyelonephritis in children (APN) [3]

Etiology

• Ascending infection from lower UTI
  • Most common route of spread
  • Causative pathogens: typically bacterial; most commonly E. coli
• Hematogenous spread
  • May occur in chronically ill and/or immunocompromised individuals
  • Causative pathogens: Staphylococcus spp., fungi

Clinical features

• APN is more common in young children.
• Upper UTI symptoms, often with lower UTI symptoms
• See “Clinical features of pediatric UTI” for nonspecific symptoms.

Diagnosis

Diagnostic criteria

APN in children is typically diagnosed based on the following:

• Clinical features of upper UTI
• Bacteriuria [3]
• Pyuria

Some patients present with low bacterial colony counts and no pyuria; diagnosis may be made clinically. [3]

Diagnostic studies

• ↑ CRP and/or procalcitonin suggest APN but are not diagnostic. [3][14]
• Imaging in pediatric UTI is not routinely indicated for acute infection but may be obtained to exclude complications or underlying pathology; findings include: [3]
  • RBUS: normal or nonspecific renal edema and hyperemia
  • Dimercaptosuccinic acid scan (DMSA scan): renal cortical defects
• Assessment for chronic complications: DMSA scan 4–6 months after infection may reveal renal scarring. [3]

RBUS cannot diagnose APN. [3]

Treatment [3]

• Start a third-generation cephalosporin; see “Treatment of pediatric UTI” for dosing.
• Clinical improvement (e.g., fever resolution) within 48–72 hours: Continue antibiotics for 7–10 days. [3]
• No response within 48–72 hours
  • Obtain renal ultrasound to exclude complications (e.g., renal abscess) that require a longer duration of antibiotics. [3]
  • Consider specialist consultation (e.g., nephrology, urology, infectious diseases) for advanced diagnostics.

Approach [2][3]

UTIs are typically diagnosed using urinalysis abnormalities (i.e., pyuria and/or visualized bacteria) and urine culture to confirm bacteriuria.

• Perform urinalysis if indicated based on age and clinical features.
• Send urine culture if urinalysis suggests UTI or if normal but clinical suspicion for UTI is high.
• Obtain imaging for UTI in children with:
  • Age ≤ 6 years and first febrile UTI [15]
  • Atypical pediatric UTI
  • Recurrent UTI

Diagnosis may also be made clinically (e.g., in patients with suggestive clinical features but low colony counts and/or no pyuria). [2][3]

Urine studies [2][3]

Collection methods [3]

• Not toilet trained
  • Preferred: sterile collection (e.g., transurethral catheterization or suprapubic aspiration)
  • Alternatives: clean-catch urine sample or bagged urine sample (not suitable for culture) [2][16]
• Toilet trained: clean-catch urine sample

Urinalysis [3]

Indications

• Age < 2 months: any ill-appearing and/or febrile infant (see "Approach to suspected neonatal bacterial infection" and “Fever in infants ≤ 60 days of age”) [16]
• Age 2–24 months: Consider the following features or use risk stratification tools (e.g., UTICalc) to determine need for urinalysis. [17]
  • Fever: ≥ 39°C (102.2°F), lasting ≥ 48 hours, and/or with no other apparent source [18]
  • Clinical features of pediatric UTI
  • History of prior UTI
  • Presence of risk factors for pediatric UTI
• Age > 24 months with clinical features of pediatric UTI

Findings

• On dipstick urinalysis [3]
  • Positive urinary nitrites: suggests bacteriuria
  • Positive leukocyte esterase: suggests pyuria
• On microscopy
  • Presence of bacteria on Gram stain and/or pyuria suggests UTI. [3]
  • Normal findings on urinalysis generally rule out a UTI, but some uropathogens do not cause pyuria or bacteriuria. [3]

Urine culture [2][3]

Indications

• Urinalysis positive for pyuria and/or bacteruria
• Normal urinalysis but high clinical suspicion for UTI

Some uropathogens may not cause detectable pyruia. In patients with significant urinary symptoms and/or risk factors for pediatric UTI, obtain culture for a definitive diagnosis even in the absence of pyuria.[3]

Findings

• Significant bacteriuria confirms the diagnosis.
• Thresholds vary based on collection method and across guidelines; follow local protocols.
  • Clean-catch urine sample: > 100,000 CFU/mL [2][3][6]
  • Transurethral catheterization: > 50,000 CFU/mL [3]
  • Suprapubic aspiration: 1000 CFU/mL [3]

Imaging for pediatric UTI

Imaging is indicated in selected patients to evaluate for urinary tract anomalies (e.g, VUR, posterior urethral valves) and/or complications of UTI (e.g., renal abscess, APN).

• Initial imaging for first febrile UTI in children [2][3][15]
  • Infants aged < 2 months: RBUS ± either VCUG or VUS [15]
  • Infants and children aged 2 months–6 years: RBUS [3]
  • Children aged > 6 years: Imaging is not recommended. [15]
• Imaging for atypical pediatric UTI and/or recurrent UTI [2][3][15]
  • Atypical pediatric UTI at any age: RBUS and either VCUG or VUS
  • Recurrent UTI: RBUS and, if ≥ 2 febrile UTIs, VCUG [15]

If RBUS and/or VCUG are abnormal, a specialist may recommend additional imaging. [3][15]

RBUS [2][3][15]

• Indications
  • First febrile UTI in children aged ≤ 6 years
  • Atypical pediatric UTI or recurrent UTI at any age
• Timing [3]
  • Severe presentation and/or failure to respond to 48–72 hours of antibiotics: during acute infection
  • Uncomplicated clinical course: after resolution of infection; typically within 6 weeks
• Potential findings
  • Features suggestive of UTI
    • Lower UTI: normal or thickened bladder wall with bladder debris [3]
    • Upper UTI: normal or nonspecific kidney edema and/or hyperemia [3]
    • Renal parenchyma changes (not sensitive)
  • Conditions that predispose to UTI
    • Congenital anomalies of the kidneys
    • Abdominal masses affecting the urinary system
    • Secondary signs of vesicoureteral reflux (VUR) [2][3]
    • Nephrolithiasis
  • Complications (e.g., renal abscess)

RBUS is typically the initial imaging modality for pediatric UTIs, as it can detect most structural abnormalities and does not involve radiation. [3][15]

VCUG or VUS [2][3][15]

VUS is less invasive than VCUG and does not involve radiation.

• Indications
  • Abnormal RBUS
  • Atypical pediatric UTI
  • Recurrent febrile UTIs
• Potential findings
  • Visualization of VUR (see “Diagnostics of VUR”) [2][3]
  • Obstructive uropathy (e.g., stenosis, hydronephrosis)

Advanced imaging [3][7][15]

• Nuclear medicine cystography: may be used to evaluate for VUR
• Dimercaptosuccinic acid scan (DMSA scan) [3]
  • Acute findings: renal cortical defects in acute pyelonephritis
  • Nonacute findings (e.g., 4–6 months after acute infection) : gold standard for identification of renal scarring [3]

Approach [2][3]

• Start empiric antibiotics for pediatric UTI while awaiting urine culture results.
• Assess for admission criteria.
• Adjust treatment when culture results become available.
  • Negative culture: Stop antibiotics and consider differential diagnoses of pediatric UTI.
  • Confirmed UTI: Alter treatment as needed based on antibiotic sensitivities.
• Provide supportive treatment (e.g., analgesia, supportive care for pediatric fever).
• If fever persists for > 72 hours, consider urgent imaging for pediatric UTI to rule out renal abscess and/or acute urinary tract obstruction. [3]
• Educate patients and caregivers on prevention of pediatric UTI.
• Refer patients to a specialist (e.g., urology, nephrology) for any of the following:
  • CAKUT
  • Chronic complications of pediatric UTI
  • Management of persistent risk factors for pediatric UTI (e.g., bowel and bladder dysfunction) [2][10]

Admission criteria for pediatric UTI [3][12]

• IV antibiotics required (for indications, see “Empiric antibiotics for pediatric UTI”)
• Consider admitting patients with any of the following:
  • Age 1–2 months [16]
  • Significant renal tract anomalies [12]
  • Barriers to follow-up

Antibiotic therapy

• Follow local guidelines and protocols if available.
• Always check local resistance patterns before initiating treatment.

Avoid empiric antibiotic monotherapy with amoxicillin or other penicillins because of resistance. [3]

Repeat urine culture is not necessary unless symptoms persist. [3]

• Vulvovaginitis (e.g., from poor hygiene, irritation) [20][21]
• Appendicitis or mesenteric lymphadenitis [21][22]
• Diabetes mellitus or arginine vasopressin disorders (may cause urinary frequency) [20]
• Genital injury [23]
• Sexually transmitted infections [20]

Consider sexual assault in all pediatric patients presenting with genital injury or sexually transmitted infections; in adolescents, screen for signs of human trafficking.

The differential diagnoses listed here are not exhaustive.

• Acute [2][3]
  • Dehydration and hypovolemia
  • Pediatric sepsis
  • Renal abscess
  • Acute kidney injury
• Chronic [2][3]
  • Recurrent UTIs
  • Renal scarring (from recurrent APN) can result in:
    • Chronic kidney disease
    • Hypertension in children

We list the most important complications. The selection is not exhaustive.

• Educate caregivers on nonspecific symptoms of pediatric UTI and the need to seek early treatment.
• Promptly identify and treat any underlying conditions, including:
  • Bladder and bowel dysfunction (see “Constipation in children and adolescents”) [2][10]
  • CAKUT (e.g., hydronephrosis, vesicoureteral reflux)
• Encourage children to urinate regularly. [10]
• Consider recommending an increase in fluid intake. [24]
• Uncircumcised boys: Encourage daily gentle retraction of the foreskin for cleaning. [10]
• Discuss antibiotic prophylaxis for recurrent UTIs with a specialist; use is controversial. [2][10]
  • Long-term antibiotic use is associated with a high risk of resistance.
  • Trials have shown limited or no benefit. [25][26]
  • Use is typically limited to patients with high-risk CAKUT and young infants [10]
• Some evidence suggests that probiotics and cranberry supplements may prevent recurrence, but further research is required. [27]

UTI 1-year recurrence rates are as high as 30%. Children with a history of UTIs should be seen within 48 hours if they experience an unexplained fever or symptoms of a pediatric UTI. [2][3][28]