Asymptomatic Bacteriuria in Children: Diagnosis and Management
Primary Recommendation
Do not screen for or treat asymptomatic bacteriuria in infants and children. 1 This is a strong recommendation from the Infectious Diseases Society of America (IDSA) 2019 guidelines, meaning it should be applied to essentially all pediatric patients with asymptomatic bacteriuria. 1
Diagnostic Criteria for Asymptomatic Bacteriuria
Definition
Asymptomatic bacteriuria is defined as the presence of bacteria in urine without clinical symptoms of infection and without pyuria (white blood cells in urine). 1, 2
Key Diagnostic Features
The critical distinguishing factor is the absence of pyuria:
- True UTI requires BOTH bacteriuria AND pyuria 1, 2
- Asymptomatic bacteriuria = bacteriuria WITHOUT pyuria 1, 2
- The presence of pyuria is what separates true infection requiring treatment from asymptomatic colonization that should be left alone 1, 2
Quantitative Thresholds
For proper diagnosis, use these colony count criteria: 1, 2
- Two consecutive voided specimens in girls: ≥10⁵ CFU/mL of the same organism 1
- Single voided specimen in boys: ≥10⁵ CFU/mL 1
- Single catheterized specimen: ≥10² CFU/mL (more reliable, lower threshold due to reduced contamination) 1
- Suprapubic aspiration: Any growth may be significant 2
Specimen Collection Pitfalls
Avoid perineal bag collection - this method dramatically overstates bacteriuria rates due to high contamination risk and should never be used for diagnosis. 1 Use catheterization or suprapubic aspiration for reliable results in young children who cannot provide clean-catch specimens. 1
Management: Why NOT to Treat
Evidence Against Treatment
Asymptomatic bacteriuria in children with normal urinary tracts does not cause harm: 1
- No cases of renal scarring were observed in children with asymptomatic bacteriuria followed longitudinally 1
- Only 4% of children with asymptomatic bacteriuria subsequently developed acute pyelonephritis 1
- Asymptomatic bacteriuria is rare in children with normal urinary tracts (0.5-2.5% prevalence depending on age and sex) 1
Treatment causes more harm than good: 1, 3
- Antimicrobial treatment may increase short-term frequency of symptomatic infections 3
- Promotes antimicrobial resistance 3
- Exposes children to unnecessary adverse drug effects 3
- Screening programs are costly and fail to prevent pyelonephritis or renal scarring 4
Quality of Historical Evidence
The IDSA acknowledges that most evidence on pediatric asymptomatic bacteriuria comes from studies in the 1970s-1980s with substantial methodological limitations (poor case definitions, small sample sizes, lack of randomization, no placebo groups). 1 Despite these limitations, the consistent finding across studies is that treatment provides no benefit and may cause harm. 1, 4, 3
Clinical Algorithm for Evaluation
Step 1: Assess for Symptoms
Look for specific urinary symptoms: 5
- Dysuria, frequency, urgency
- Suprapubic pain
- Fever (in infants/young children)
- New-onset gross hematuria
- Flank pain
If ANY symptoms are present → This is NOT asymptomatic bacteriuria; evaluate and treat as symptomatic UTI 5
Step 2: Verify Pyuria Status
Check urinalysis for white blood cells: 1, 2
- Pyuria present (≥10 WBC/mm³) → True UTI, requires treatment 1, 2
- No pyuria → Asymptomatic bacteriuria, do NOT treat 1, 2
Important caveat: Pyuria alone without bacteriuria is nonspecific and occurs in non-infectious conditions (Kawasaki disease, chemical urethritis, streptococcal infections). 1, 2, 6
Step 3: Confirm Proper Specimen Collection
Verify the urine was collected appropriately: 1, 6
- Catheterization or suprapubic aspiration preferred in young children
- Clean-catch acceptable in older toilet-trained children
- Never use bag collection for diagnosis 1
Special Populations and Exceptions
When Screening/Treatment IS Indicated
The IDSA 2019 guideline makes NO exceptions for children - the recommendation against screening and treatment applies to all infants and children, including those with: 1
- Vesicoureteral reflux (VUR)
- History of recurrent UTIs
- Renal abnormalities
However, older research (1990) suggested treatment for: 7
- Neonates and preschool children (this conflicts with current IDSA guidelines)
- Children undergoing genitourinary instrumentation or manipulation 7
The most recent and authoritative guideline (IDSA 2019) supersedes these older recommendations and states clearly: do not screen or treat asymptomatic bacteriuria in children, period. 1
Common Pitfalls to Avoid
Pitfall #1: Treating Bacteriuria Without Pyuria
Never treat bacteriuria in the absence of pyuria - this represents either contamination or asymptomatic colonization, not infection. 1, 2 The absence of leukocyte esterase on urinalysis is actually an advantage, as it helps distinguish asymptomatic bacteriuria from true UTI. 1
Pitfall #2: Misinterpreting Nitrite Tests
Negative nitrite tests do not rule out UTI in children because: 1
- Nitrite formation requires ~4 hours of bladder incubation 1
- Infants and young children empty bladders frequently 1
- Not all uropathogens reduce nitrate to nitrite 1
However, positive nitrite tests are highly specific (few false positives), so a positive result supports the diagnosis of true UTI when symptoms or pyuria are present. 1
Pitfall #3: Unnecessary Screening Programs
Do not implement routine screening for asymptomatic bacteriuria in well-child care - screening is costly (nearly $2.9 million per 100,000 children screened), has high false-positive rates (20%), and fails to prevent pyelonephritis or renal scarring. 4
Pitfall #4: Confusing Contaminants with Pathogens
Recognize common contaminants: 2
- Lactobacillus species
- Coagulase-negative staphylococci
- Corynebacterium species
These organisms in urine culture represent contamination, not true infection. 2
Summary of Evidence Strength
The recommendation against screening and treatment is based on: 1
- Strength: Strong recommendation (should be applied to essentially all patients)
- Quality: Low-quality evidence (due to methodological limitations of older studies)
- Rationale: Despite low-quality evidence, the recommendation is strong because there is no demonstrated benefit to treatment and clear evidence of potential harms (antimicrobial resistance, adverse effects, increased symptomatic infections)
This represents a situation where the IDSA made a strong recommendation despite low-quality evidence because the potential harms of treatment outweigh uncertain benefits. 1