Incidence of UTIs in Infant Girls
The incidence of urinary tract infections (UTIs) in infant girls is approximately 6.5% in those under 1 year of age, increasing to about 8.1% in girls between 1 and 2 years of age. 1
Epidemiology and Risk Factors
UTIs are common in children, with significant variation in prevalence based on age, gender, and other risk factors:
- Girls under 1 year: 6.5% prevalence rate 1
- Girls 1-2 years: 8.1% prevalence rate 1
- Overall, approximately 5% of febrile infants with no obvious source of fever have UTIs 1
- Female gender is a significant risk factor, with girls having more than twice the prevalence compared to boys (except in early infancy) 1
Risk Factors Specific to Infant Girls
The likelihood of UTI in infant girls increases with the following risk factors:
- White race
- Age less than 12 months
- Temperature ≥39°C
- Fever for at least 2 days
- Absence of another source of infection 1
Clinical Presentation
UTIs in infant girls often present with non-specific symptoms:
- Fever (most common symptom)
- Irritability
- Poor feeding
- Vomiting
- Diarrhea
- Foul-smelling urine (when reported by caregivers)
- Changes in urinary voiding pattern 1
Risk Assessment
The American Academy of Pediatrics provides a clinical decision rule to identify infant girls at low risk for UTI:
- Girls with no more than 1 of the 5 risk factors (white race, age <12 months, temperature ≥39°C, fever ≥2 days, absence of another infection source) have <1% probability of UTI 1
- Girls with 2 or more risk factors have increasing probability of UTI:
- 2 factors: 0.9% probability
- 3 factors: 1.0% probability
- 4 factors: 2.4% probability
- 5 factors: 1.7% probability 1
Diagnostic Considerations
When UTI is suspected in an infant girl:
- Urine specimen should be obtained via catheterization or suprapubic aspiration (not bag collection) to avoid contamination 2
- Diagnosis requires both:
- Pyuria (presence of WBCs in urine)
- ≥50,000 CFU/mL of a single uropathogenic organism 2
Clinical Implications
The high incidence of UTIs in infant girls has important clinical implications:
- Approximately 75% of children under 5 years with febrile UTIs have upper tract disease (pyelonephritis) 1
- Renal scarring can occur in 27-64% of children after pyelonephritis 1
- Young children, especially those under 1 year, are at highest risk for renal scarring 1
- Delayed therapy increases risk of renal scarring 1
- Long-term complications of renal scarring include 10-20% risk of hypertension and 10% risk of end-stage renal disease 1
Prevention of Complications
To prevent complications in infant girls with UTIs:
- Early diagnosis with appropriate urine specimen collection techniques
- Prompt treatment with appropriate antibiotics
- Renal and bladder ultrasound for first febrile UTI
- Consider voiding cystourethrography (VCUG) for recurrent UTIs or abnormal ultrasound findings 2
UTIs in infant girls represent a significant clinical concern requiring vigilance from healthcare providers, especially given the non-specific presentation and potential for serious long-term complications if not properly diagnosed and treated.