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Screening for urinary tract infection in infants in the emergency department: which test is best?
K N Shaw1, K L McGowan, M H Gorelick
1Department of Pediatrics, Children's Hospital of Philadelphia, PA 19104, USA.
Insights
Detecting urinary tract infections (UTIs) in infants requires careful consideration of rapid tests and screening strategies. The most cost-effective approach involves culturing all infant urine samples and treating based on positive dipstick results, ensuring all UTIs are detected.
Area of Science:
- Pediatrics
- Infectious Diseases
- Clinical Diagnostics
Background:
- Urinary tract infections (UTIs) are common in infants, necessitating accurate and efficient diagnostic methods.
- Rapid diagnostic tests and screening strategies are crucial for timely detection and treatment of UTIs in young children.
- Evaluating the sensitivity, specificity, and cost-effectiveness of different UTI detection methods in infants is essential for clinical practice.
Purpose of the Study:
- To compare the effectiveness and cost of various rapid tests and screening strategies for detecting urinary tract infections (UTIs) in infants.
- To determine the optimal diagnostic approach for identifying UTIs in infants presenting to an emergency department.
Main Methods:
- A cross-sectional study involving 3873 infants under two years of age who underwent urine culture via urethral catheterization.
- Comparison of urine dipstick tests (leukocyte esterase, nitrites), enhanced urinalysis (UA), Gram stain, and combined methods against urine culture results.
- Cost analysis of different screening strategies, including dipstick plus universal culture versus enhanced UA with selective culture.
Main Results:
- The enhanced UA demonstrated the highest sensitivity (94%) but also higher false-positive rates (16%) compared to dipstick or Gram stain (3%).
- The most cost-effective strategy involved culturing all urine specimens and initiating presumptive treatment for infants with positive dipstick results (leukocyte esterase +2 or positive nitrite), costing $3.70 per child and detecting all UTIs.
- Using enhanced UA for screening would reduce cultures by 82% but miss 4-6% of UTIs and increase costs to $6.66 per child.
Conclusions:
- No single rapid test can reliably detect all infant UTIs; universal urine culture is recommended.
- Presumptive treatment should be initiated only for infants with significantly positive dipstick results.
- Enhanced UA is highly sensitive but less specific and more costly, making it suitable for neonates where missing a UTI is critical.
Objective:
Comparison of rapid tests and screening strategies for detecting urinary tract infection (UTI) in infants.
Methods:
Cross-sectional study conducted in an urban tertiary care children's hospital emergency department and clinical laboratories of 3873 infants <2 years of age who had a urine culture obtained in the emergency department by urethral catheterization; results of urine dipstick tests for leukocyte esterase or nitrites, enhanced urinalysis (UA) (urine white blood cell count/mm3 plus Gram stain), Gram stain alone, and dipstick plus microscopic UA (white blood cells and bacteria per high-powered field) compared with urine culture results (positive urine results defined as >/=10 colony-forming units per milliliter of urinary tract pathogen) for each sample. Cost comparison of 1) dipstick plus culture of all urine specimens versus 2) cell count +/- Gram stain of urine, culture only those with positive results.
Results:
The enhanced UA was most sensitive at detecting UTI (94%; 95% confidence interval: 83,99), but had more false-positive results (16%) than the urine dipstick or Gram stain (3%). The most cost-effective strategy was to perform cultures on all infants and begin presumptive treatment on those whose dipstick had at least moderate (+2) leukocyte esterase or positive nitrite at a cost of $3.70 per child. With this strategy, all infants with UTI were detected. If the enhanced UA was used to screen for when to send the urine for culture, 82% of cultures would be eliminated, but 4% to 6% of infants with UTI would be missed and the cost would be higher ($6.66 per child).
Conclusion:
No rapid test can detect all infants with UTI. Physicians should send urine for culture from all infants and begin presumptive treatment only on those with a significantly positive dipstick result. The enhanced UA is most sensitive for detecting UTI, but is less specific and more costly, and should be reserved for the neonate for whom a UTI should not be missed at first visit.