From the Guidelines
The criteria for diagnosing a urinary tract infection (UTI) include the presence of urinary symptoms such as painful urination (dysuria), frequent urination, urgency, suprapubic pain, and hematuria, along with laboratory evidence of bacteriuria, with a urine culture yielding >10,000 colony-forming units of a uropathogen per milliliter of urine being the fundamental confirmatory diagnostic test 1.
Key Diagnostic Criteria
- Urinary symptoms: dysuria, frequent urination, urgency, suprapubic pain, and hematuria
- Laboratory evidence of bacteriuria: pyuria and/or bacteriuria
- Urine culture: >10,000 colony-forming units of a uropathogen per milliliter of urine
Patient Presentation
Patients with flank pain or tenderness, without or with voiding symptoms, without or with fever, and with a urinalysis showing pyuria and/or bacteriuria, should be considered for a presumptive diagnosis of acute pyelonephritis (APN) 1.
Special Considerations
- In young healthy women, Escherichia coli accounts for more than 90% of APN cases 1
- In men, elderly women, and urologically compromised and institutionalized patients, less-virulent E. coli strains, gram-negative bacilli, gram-positive organisms, and candida are also common 1
- Risk factors for cystitis predispose to APN and include sexual activity, new sexual partner, spermicide exposure, personal or maternal history of UTIs, genetic predisposition, and diabetes mellitus 1
From the Research
Criteria for UTI Diagnosis
The diagnosis of urinary tract infections (UTIs) can be made based on several criteria, including:
- Urinary symptoms such as dysuria, frequency, and urgency 2, 3, 4, 5
- Pyuria, which is the presence of white blood cells in the urine 3, 4, 6
- Bacteriuria, which is the presence of bacteria in the urine 3, 4, 6
- Physical examination findings, such as suprapubic tenderness 2
- Urinalysis results, including dipstick testing and microscopic examination 2, 3, 5
- Urine culture results, which are considered the gold standard for diagnosing UTIs 3, 4, 5, 6
Diagnostic Considerations
When evaluating a patient for a UTI, it is essential to consider the following:
- The patient's symptoms and medical history 2, 3, 4, 5
- The results of urinalysis and urine culture 2, 3, 4, 5, 6
- The presence of comorbidities or urologic abnormalities 2
- The patient's age and sex, as UTIs can present differently in different populations 3, 4, 5
- The possibility of other conditions that may cause similar symptoms, such as sexually transmitted infections or bladder irritants 5
Laboratory Testing
Laboratory testing, including urinalysis and urine culture, plays a crucial role in diagnosing UTIs. The following tests can be used:
- Dipstick urinalysis to detect the presence of nitrites, leukocyte esterase, and blood in the urine 3
- Microscopic urinalysis to detect the presence of white blood cells, red blood cells, and bacteria in the urine 3, 5
- Urine culture to detect the presence of bacteria in the urine and to guide antibiotic therapy 2, 3, 4, 5, 6