From the Guidelines
A urinalysis is a crucial diagnostic test for urinary tract infections (UTIs), and it should be interpreted in the context of clinical symptoms and medical history, as recommended by the recent guidelines for UTI management 1. When evaluating a urinalysis for UTI, look for the presence of:
- Leukocyte esterase
- Nitrites
- White blood cells (>5-10 WBCs/hpf)
- Bacteria Positive leukocyte esterase indicates white blood cells in the urine, while positive nitrites suggest the presence of gram-negative bacteria. The gold standard for diagnosis is a urine culture, which should be obtained before starting antibiotics, as emphasized in the guidelines for the prevention, diagnosis, and management of urinary tract infections in pediatrics and adults 1. First-line treatment for uncomplicated UTIs typically includes:
- Nitrofurantoin (100mg twice daily for 5 days)
- Trimethoprim-sulfamethoxazole (160/800mg twice daily for 3 days)
- Fosfomycin (3g single dose) For complicated UTIs or pyelonephritis, fluoroquinolones or broader-spectrum antibiotics may be needed for 7-14 days, as suggested by the recent consensus statement on UTI management 1. Patients should increase fluid intake, urinate frequently, and complete the full antibiotic course even if symptoms improve. UTIs are caused by bacteria ascending the urethra into the bladder, with E. coli being the most common pathogen, and certain populations such as women, elderly individuals, and those with urinary catheters or structural abnormalities are at higher risk for developing UTIs, as noted in the guidelines 1.
From the Research
Urine Analysis for UTI Diagnosis
- Urine analysis is a common method used to diagnose urinary tract infections (UTIs) 2, 3.
- The sensitivity and specificity of urine dipstick tests, such as leukocyte esterase and nitrite tests, have been evaluated in several studies 2, 3.
- A study published in 2013 found that the sensitivity of leukocyte esterase test was 63.6% and the combined leukocyte esterase and nitrite test was 66.7% 2.
- Another study published in 2015 found that the sensitivity and specificity of urine dipstick tests were 75.74% and 68.90%, respectively 3.
Predicting Causative Agent and Antibiotic Sensitivities
- Urine analysis can also be used to predict the causative agent of UTI and antibiotic sensitivities 4.
- A study published in 2014 found that positive leukocyte esterase and nitrites were associated with Escherichia coli (E. coli) infections, while negative urine analysis results were more likely to be associated with non-E. coli organisms 4.
- The study also found that antibiotic sensitivities differed between E. coli and non-E. coli groups, with E. coli being more sensitive to cefazolin, cefuroxime, and nitrofurantoin, and non-E. coli organisms being more sensitive to trimethoprim-sulfamethoxazole 4.
Clinical Presentations and Epidemiology of UTIs
- UTIs are one of the most common bacterial infections, with a higher incidence in women than men 5.
- The diagnosis of UTI can be made based on a combination of symptoms and a positive urine analysis or culture 5, 6.
- Uncomplicated UTIs can be diagnosed and treated based on symptoms alone, while complicated UTIs require further evaluation and treatment 5, 6.