Urinary tract infection (peds)

This page is for pediatric patients; see Acute cystitis for adult patients.

Background

• Most common SBI, accounts for 5-8% of children presenting for fever without clear source
• Associated with bacteremia in up to 30% of infants 4-8wk of age
• E. coli is responsible for ~80% of UTIs
• After 1yr of age, occult UTI with normal UA extremely rare
• After 2yr of age, UTI remains common in girls (but associated with symptoms)
• UTI in adolescent girl is suggestive of intercourse
• Prevalence of UTI in bronchiolitis is only 0.8% based on 2019 meta-analysis, which is far lower than in previous studies, suggesting less need for automatic testing for UTI in bronchiolitis

Clinical Features

• Infants/young children: fever without other source
• Older children:
  • Dysuria, frequency, or other urinary complaints
  • +/- abdominal/back pain
• UTI + fever = pyelonephritis

Differential Diagnosis

Pediatric Abdominal Pain

0–3 Months Old

• Emergent
  • Necrotizing Enterocolitis
  • Volvulus
  • Testicular torsion
  • Inguinal hernia
    • Incarcerated hernia
  • Trauma
  • Pyloric stenosis
  • Toxic megacolon
  • Hirschsprung's Disease
• Nonemergent
  • Constipation
  • Acute Gastroenteritis
  • Colic

3 mo–3 y old

• Emergent
  • Intussusception
  • Testicular Torsion
  • Trauma
  • Volvulus
  • Appendicitis
  • Toxic megacolon
  • Vaso-occlusive crisis
• Nonemergent
  • Acute Gastroenteritis
  • Constipation
  • Urinary tract infection
  • Henoch-Schonlein purpura

3 y old–adolescence

• Emergent
  • Appendicitis
  • DKA
  • Vaso-occlusive crisis
  • Toxic ingestion
  • Testicular Torsion
  • Ovarian Torsion
  • Ectopic Pregnancy
  • Trauma
  • Toxic megacolon
  • Inflammatory bowel disease
  • Gastric ulcer disease
  • Ovarian cyst
  • Pregnancy
  • Pancreatitis
  • Cholecystitis
  • Intussusception (to age 6)
• Nonemergent
  • Constipation
  • Acute Gastroenteritis
  • Nonspecific viral syndrome
  • Streptococcus pharyngitis
  • Urinary tract infection
  • Pneumonia
  • Renal Stone
  • Henoch-Schonlein purpura
  • Inflammatory bowel disease
  • Vulvovaginitis

Pediatric fever

• Upper respiratory infection (URI)
• UTI
• Sepsis
• Meningitis
• Febrile seizure
• Pneumonia
• Acute otitis media
• Whooping cough
• Unclear source
• Kawasaki disease
• Neonatal HSV
• Specific virus
  • COVID-19 (peds)

Evaluation

• University of Pittsburgh UTI Calc
• Children's Hospital of Philadelphia UTI pathway

Labs

• Urinalysis
  • Obtain clean catch specimen OR cath UA
    • Neg UA = neg LE, nit, GS & <5 WBC
  • Bag urine results in 83% false positive; only useful if negative
    • UTI diagnosis cannot be established reliably through bag urine culture (Evidence A; strong recommendation; AAP 2011)
• Urine culture
  • Send on all patients except for:
    • 1. Low-risk patients with normal UA and another explanation for symptoms
    • 2. Older adolescent females with very high post-test probability without severe illness
  • 20% of +Urine culture will have negative UA
  • Do not send urine bag specimen for culture when UA is negative and clinical suspicion is relatively low
    • False positives are high due to bag contamination

Test Characteristic Ranges				Post-test Probability (%) of UTI in Different Patients
Test	Sensitivity (%)	Specificity (%)	Test Result	LR	Patient A	Patient B	Patient C	Patient D	Patient E
Leukocyte esterase	67–85	81–92	+	3.5–10.6	21–45	2–5	23–49	20–43	26–52
			–	0.16–0.41	1–3	<1	1–3	1–3	2–4
Nitrite*	21–69	95–99	+	4.2–69	24–84	2–26	26–86	22–83	29–87
			–	0.31–0.83	2–6	<1	3–7	2–5	3–8
Leukocytes on microscopy	51–91	45–91	+	0.90–10.1	6–43	0–5	7–47	6–41	8–50
			–	0.10–1.09	1–8	0–1	1–9	1–7	1–10
Bacteria on microscopy	46–96	11–96	+	0.5–24.0	4–64	0–11	4–68	3–63	5–70
			–	0.04–4.91	<1–27	<1–2	<1–30	<1–25	<1–33
Bacteria on Gram stain	80–97	87–99	+	6.2–97	32–88	3–33	35–89	30–87	38–91
			–	0.03–0.23	<1–2	<1	<1–2	<1–2	<1–2
Combined tests
Any positive test on dipstick	99–100	63–70	+	2.7–3.3	13–20	1–2	19–22	16–19	21–25
			–	0.00–0.02	<1	<1	<1	<1	<1

Patient A: Female patient in ED, <1 year old, fever with no definitive source on examination, pretest probability of UTI is 7%.

Patient B: Male patient in ED, <1 year old, circumcised, fever with no definitive source on examination, pretest probability of UTI is 0.5%.

Patient C: Male patient in ED, <1 year old, uncircumcised, fever with no definitive source on examination, pretest probability of UTI is 8%.

Patient D: Female patient in ED, 2–6 years old, no fever but GU symptoms, pretest probability of UTI is 6.5%.

Patient E: Female patient in ED, adolescent age range, no fever but urinary symptoms, pretest probability of UTI is 9%

Management

• Know your local resistance patterns and make sure to send a urine culture
• Do not use nitrofurantoin in children (need bloodstream penetration)

<1mo

• Admit for IV antibiotics
  • Ceftazidime 150mg/kg/d divided every 6 h

1mo - 2yo

• Ceftriaxone 50mg/kg in ED
• Cephalexin 50-100mg/kg/d in 4 divided doses x14d
  • Maximum dose (all ages) 4g/24hr

>2yo

• Amoxicillin
  • Mild to moderate infections (>40kg): 500mg PO BID for x10-14d
• Cephalexin 50-100mg/kg/d in 4 divided doses x7d
• Cefaclor 50-100 mg/kg/d divided in 3 doses x5d
• Cefixime 8 mg/kg daily x 5d

>13yr adolescent

• Consider 3 day course of treatment

Disposition

Admit

• <1 month old
• Toxic
• Inability to tolerate POs

Discharge

• 1mo - 2yr, who are well-appearing and not vomiting
  • 24-hour follow up
• >2 years old
  • 48-hour follow up

See Also

• Urinary tract infections