Symptoms of UTI in Infants
Fever is the most common symptom of urinary tract infection in infants, but the presentation is typically nonspecific and may include vomiting, diarrhea, irritability, poor feeding, or simply unexplained fever without any localizing signs. 1, 2
Primary Clinical Manifestations
Most Common Presentations
- Fever (present in approximately 77-78% of cases) is the predominant symptom, often defined as temperature ≥38.0°C (100.4°F) 1, 2, 3
- Irritability occurs in approximately 41% of infants with UTI 3
- Vomiting is seen in about 25% of cases 3
- Poor feeding or failure to thrive may be the only presenting sign in some infants 2, 4
Additional Warning Signs
- Foul-smelling urine increases the likelihood of UTI 2
- Crying during urination may indicate infection 2
- Changes in urinary voiding patterns should raise suspicion 2
Age-Specific Considerations
Infants Under 2-3 Months
- Presentation mimics neonatal sepsis with nonspecific symptoms 1
- Concomitant bacteremia occurs in 4-36.4% of cases in this age group, making this a high-risk population 1, 5
- These infants require urgent evaluation and often hospitalization 2, 5
Infants 2-24 Months
- Symptoms remain nonspecific and similar to viral illnesses 1, 2
- The only reliable way to differentiate UTI from viral infection is through urine testing 4
- Fever without an obvious source should prompt consideration of UTI, as the prevalence is approximately 5% in this population 1, 6
Key Clinical Pitfalls to Avoid
- Do not rely on the absence of fever to rule out UTI, as not all children with UTI will be febrile 1
- Do not assume another source of fever excludes UTI: infants with apparent sources like otitis media still have a 3.5% prevalence of UTI, though this is lower than the 7.5% in those without an apparent source 6
- Recognize that symptoms overlap significantly with other common childhood illnesses, making urine testing essential when UTI is a consideration 1, 4
- Be aware that male infants, particularly uncircumcised boys under 6 months, have significantly higher UTI risk (up to 12.4% prevalence) despite UTI being more common in females after the first year of life 2, 5
When to Suspect UTI
Any infant under 24 months with unexplained fever should be evaluated for UTI, particularly: 1, 2