UTI: Urinary Tract Infection

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Updated by: Jonathan Ellison MD
Updated on: 5/5/2021


Signs and symptoms:

  • Upper tract (i.e. pyelonephritis): fever > 38° C, nausea/vomiting, flank pain, general malaise
  • Lower tract (i.e. cystitis): dysuria, frequency/urgency, incontinence, suprapubic pain, change in urine odor or color
  • Neonates/Infants: fever > 38° C, irritability, poor feeding, vomiting, diarrhea, failure to thrive, jaundice, sepsis


75% of urinary tract infections are cause by Escherichia coli. The next most common pathogens are Klebsiella and Proteus, followed by Staphylococcus and Enterococcus.

Referring provider's initial evaluation and management


  • Catheterized specimen: Urinalysis suggestive of infection (pyuria and/or bacteriuria) AND > 50,000 colony‐forming units (CFUs) per mL of a uropathogen cultured. Alternatively, > 10,000 CFUs/mL may be considered a possible UTI depending on initial index of suspicion.
  • Clean catch specimen: In a symptomatic child, positive urinalysis AND > 100,000 CFUs/mL of a single uropathogen from a voided clean‐catch specimen is also diagnostic. Alternatively, >50,000 CFUs/mL may be considered a possible UTI depending on initial index of suspicion.


  • Leukocyte esterase test: 71-86% sensitive in the context of clinically suspected UTI
  • Nitrite test: highly specific; not sensitive in children who empty their bladders frequently
  • Combination LE and nitrite positive: 94% sensitive for clinically suspected UTI
  • Culture results of urine collected in a bag applied to the perineum are only valid when negative and are not routinely encouraged for this reason

Treatment and drugs

  1. Behavior modification: robust hydration and frequent voiding
  2. Treatment of constipation
  3. Antibiotics
  4. RBUS and/or VCUG dependent upon number of febrile infections and/or under 6 months of age

Empiric therapy with oral antibiotics pending culture and sensitivity results:

Age >60 days to <2 years

cephalexin for 10 days
25 mg/kg/dose TID (Intravenous antibiotic treatment is highly recommended in infants who may not tolerate oral treatment)

Age 2 to <12 years

Cystitis: cephalexin for 7 days
25 mg/kg/dose [max 500 mg/dose] TID

Pyelonephritis: cephalexin for 10 days
25 mg/kg/dose [max 1000 mg/dose] TID

Age ≥12 years

Cystitis: cephalexin for 3 days
25 mg/kg/dose [max 500 mg/dose] TID

Pyelonephritis: cephalexin for 10 days
25 mg/kg/dose [1000 mg/dose] TID

Toxic‐appearing children or those who cannot tolerate oral medications should be treated parenterally

If Hx of prior UTI, select empiric therapy based on previous urine culture sensitivities

If allergy to cephalosporins or severe IgE-mediated reaction (i.e. anaphylaxis or anaphylactoid reaction) to penicillins (incl. amoxicillin), consider trimethoprim/sulfamethoxazole 5-6 mg/kg/dose [max 160 mg/dose trimethoprim for cystitis or pyelonephritis] BID for the duration recommended for cephalexin based on age and diagnosis.

When to initiate referral/ consider refer to Urology Clinic:

  1. Recurrent UTIs that are refractory to the recommended treatment
  2. Boys after the 1st febrile UTI/pyelonephritis, irrespective of imaging result
  3. Girls after the 1st febrile UTI/pyelonephritis, with abnormal imaging
  4. Boys and Girls after the 2nd febrile UTI/pyelonephritis, irrespective of imaging results
  5. Consider an outpatient referral for boys or girls after the 1st febrile UTI/pyelonephritis, if UTI required inpatient evaluation
  6. Desire by the family or the primary provider to seek specialist evaluation following the 1st febrile UTI/pyelonephritis

What can referring provider send to Urology Clinic?

  1. Using Epic referral form, please complete:
    • Urgency of the referral
    • What is the patient's chief complaint
    • Describe details
    • Pertinent past medical history
    • Abnormal lab or imaging findings
    • What is the key question you want addressed
    • Does patient have psychosocial stressors or mental health concerns
  2. Not using Epic referral form
    • Please fax (414-266-1752) the above information and include:
      • Indicate if you want consult only, or consult and management of the problems
      • Send any X‐ray films/reports with patient, if film was not done at Children's
      • Send lab work, and any office notes regarding this patient's problems

Urology office number: (414) 266-2460

Specialist's workup will likely include:

After referral to Urology Clinic:

  1. Your patient will receive testing only if it is warranted.
  2. You will receive consultation letter with assessment and plan within a week of the visit.
  3. You will receive updates any time the patient returns for follow up. You may receive a phone call if there are additional concerns.